Full text of "Hammond Organ Service Manual - Early Models (A,B,C series, B3, A-100, RT, D, G, etc.)"

See other formats

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- 1

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mCLUDINB
PARTS LIST

-.n--'

A- 100

AB, BA, BC,

BCV, BV, B2, B3,

C, CV, C2, C-2G, C3,

D, DV, D-100, E. G,

GV, RT, RT-2, RT-3

HOOO-000495

CAUTION

SEESAFETYNOTICEON
INSIDE COVER SHEET

SAFETY NOTICE

Great care has been taKdn in the destgn and manufaclure of thiB product to assure that no
shock hazard eirfsls on any exposed metal pan*. Internal service operations can expose the
technFcLan to hazardous line vollages and accldanfally caiise these voltages to appear on
exposed metal parts during repa<r or raassambly of product components. To prevent this, work
on these products should only be periormed by those who are Ihoroughly familiar with the
precaullona necessary when working on this type of equipment.

To prolMl ihe ui#r, H li FHfutrvd that all ancloture parti and iifety [nteriocki be restored 1o
their original condition and the following tetti be peHormed t>efore feturning the pfoduci to
the owner after any lervlce oper alton,

Wug th6 AC line cord directly Into a line voltage AC receptacle (do not use an Isolation
transformer for this lest) and turn the product on. Connect the network (as shown below) In
series with aM e^Kposed metat parts and a known earth ground such as a water pipe or conduit,
Uaa an AC VOM of 5,000 ohms per volt or higher senaillvity to measure the voltage drop across
the network. Move the network connection to each exposed metal part (metal chassis, screw
heads, knobs and control shafla, esculcheor^. etc.) and measure the voltage drop across the
network. Reverse the line plug and repeal the measurements. Any reading of i volts RMS or
more Ja excessive and Indicates a potential shock hazard which must be corrected before
returning the product to the user.

TEST
PROBE

von
kZ SCUE

10K

.01 MF
CER*niC RF
BYPASS CAP

TEST CUPS

CONNECTED TO WOIH
URIH GROUND

TO tIPOSED lETU PUflTS

TABLE OF COimilTS

SECTION I

GENERAL - A BRIEF DEXCRIPT1DH AND SOME ILLUSTMTIONS
OF THE FOLLOWING MODEL ORGANS AND TONE
CABINHS

ORGANS PAGE

Modvis A, AB 1-1

Mpdfli* ■ BC, BV, BCV. B-2 & B3 1-1

Modal BA (Roll Pliytf Organ) 1-2

ModffliC, CV, C-2, C-3, O&DV 1-2

Modeli G. C-2, 2G, C-3G Consolei

& G-40, HR-iOG Tona Cabinati 1-3

Madef E (Concart Modall 1-3

Modali RT, RT-Z, & RT-3 1-4

Models A-IDO. D-lOO MA

TONE CAfilNHS

Model A-20 1-5

MndBl A40 1-5

Model B-40 1-8

Modal C-ZO 1-6

Model C-40 1-7

Modal 20 1-7

Modal tfi-20 1-8

Model F-40 1-8

Modall H-40, Hfl'40, K-^O, KR-4.0 1-9

Model JR'20 1-9

Modal PH-ZD M D

Modal P-40, Q-40 1-10

Modal PR-40, QR-40 Ml

THEORY OF OPERATION M3

DaacripTion 1-13

PreiBl Keys 1-14

Padaf Toe Piiton^

(Model E Console) 1-15

Padfii Solo linit

WodeliRT. RT-Z, RT-3&D-100 1-16

Echo Switch 1-16

Tremulant 1-17

Percussion 1-17

Tone Generator 1-18

Tofie Cabinati 1-lB

Rotor Tremulant 1-18

Power Amplifier 119

ftevertjeration System 1-19

SECTION II - INSTALLATION. MAINTENANCE ANO TECHNICAL
INFORMATION

ACOUSTICS 2-1

General InilailBlJon 2-1

Reverberation 2-2

INSTALLATION « MAINTENANCE

CABLES 2-4

Block DiaQraini 2-4

Wtring Diegrama . . ., Z-5

Block Diagrams Z-5

(Rfmsl thmll) Tliru 2-8

MAIN GENERATOR (mURE 1)

91 Fraquancy Ganentor 2-9

82 Frequency Generator 2-11

Model M Generator 2-12

Generator lliuitretioni

(Figure 2 thru 6) 2-12

CHORUS GBMUTOR

Models BC, D. E. § G

JHuitntionslFiBure 1 thni3t 2-14

COmOLE POWER WIRING ^'^^^

Motor Cifcuiti (Figure 1 ) 2-15

Run Switches [Figure 2) 2-16

SidePenellFigure3&41 2-16

MANUALS ft PEDALS

Menual Assembly (Figuf a 1) 2-17

Manual Chassis

Models A. AV. B, BA, BC, C. CV, a DV, G. GV. RT , . . . 2-1 7

Kay Contact Spring (Figure 2) 2-17

Manual Contacts (Figure 3) 2-17

Manual Chassis

Models B-2, C-2, RT-2 2-18

MDdelsB-3, C'3. RT'3, A-lOa D-lOO 2-13

ModelE 2-lfl

Manual Ajring

Models A, AV, B, BA. BC, BCV. C. CV. D,

DV. t G, GV, RT 2-ig

Modall B-2, B-3. C-2. C-3. RT-2, RT-3.

A-lOaO-100 2-19

Model M Senas 2-19

Key ft Frequency Chert (Figure 4) 2-19

Pedal Switch Assembly (Figure 5) 2-20

Pedal Circuits (figure B thru 12) 2-21

thru 2-22

Pedal Switch Assembly RT-K2,3 & D-lOO 2-22A

Pedal Circuits 2-22B

Pedal Keyboard 2-22D

Models HI RT-2, RT-3 ft 0-100 2-23

Modal E 2-23

Pedal & Frequency Chen (Figure 13| 2-23

Pedal Keyboard (Figure 14) 2-24

PRESET PANELS

Modal A. AV. B, BA, BC. BCV, BV, C. CV.

a DV. G. GV, RT 2-24

Models B-2, B-3. C-2, C-3, flT-2. RT-3.

A-10Q, D-1D0. E 2-24

Charts (Figure 15) 2-25

Malchir^g Transformers 2-25

Preset Keys 2-25

Preset Cradle [Figure 16| 2-2B

TREMULANT 2-27

Models A. AB. BC, C. D, ft G 2-27

ModelE 2-27

RHEOSTAT BOX 2 27

Rhaostet Circuits (Figure 1 thru 8) 2-2B

thru 2-31

VIBRATO

Vibrato Diagram (Figure 1) 2-32

Une Box [Figure 2 & 3) 2-33

Vibrato Switch (Figure 4) 2-34

Scanner (Ftgure 5) 2-34

Modsi M 2-34

Schemetics (FigLre 8 2-35

thru 9) 2-36

PERCUSSION 2-37

Operation ■ 2-37

Percussion Cui-Dff 2-3B

REVERBERAT10H

Fluid Type 2-39

llluilralion (Figure 1 ft 2} 2-4G

Filling & Adjustment 2-41

Dry Type 2-42

PR & OR Tone Cabinete 2-43

Initallaiior^of PR & QR

Tone Cabineti - - 2-44

Service Suggaitions 2-44

Earlier Tone Cabinets 2-44

Self Contained Unite 2-44

PAGE

ECHO EQUIPMEIIT 2-45

Echo Organ Kit

Block Oiiflrams (Fiflure 1 & 2] 2-i5

Install Kit m

ModalE Z-*6

Eariy Modal B & BC 2*7

Model A 2-47

Winng of Echo Kit (f iQUfa 5 & 6) 2-48

Earphones 2-49

SECTION tfl

LIST OF ILLUSTRATIOM AND INDEX 3 1

Modals A. B. BC, 0, e.G 3-2

Wiring Diagram (Figure 15) 3-2

Schamatic (f igufe 16) 3-3

ModeU'100 3-59

Schematic (Figure 30) 3-59

Wiring Diagram (Figure 31 1 3-60

Model 9V, CV 3-4

Winng Diagram (Figure 17] 3-4

Schematic (Fiflura 18) 3-5

Model C-2G 3-6

Wiring Diagram 3-6

Schematic 3-7

Models 82 & C2 3-8

Wiring Diagram (Figure 2D) 3-8

Wiring Diagram iFigure 20A) 3-9

Schematic (Figuie 21 1 3-10

Models B-3 4 C-3 3-11

Wiring Diagram (Figure 23) 3-11

Schematic (Figure 24) 3-12

Model Dl 00 3-86

Schamatic (Figure 33) 3-66

Wiring Diagram [Figure 35) 3-67

Model E 318

Wiring Diagram (Sheet 1) 3-18

Wiring Diagram (Sheet 2} 3-19

Modal RT 3-13

Wrring Diagram (Figure 19) 3-13

Schematic IBV^BC^ & RT| (Figure 18)

SEEPAGE 3-5

Model RT-2 3-14

Wiring Diagram (Figure 22) 3-14

Wiring Diagrem (Figure 22A) 3-14

Schematic (B-2. C-2, 8i HT-2)

SEE PAGE (Figure 21 3-10

Model RT-3 3-16

Wiring Dfagram (Figure 26A| 3-16

SchBmBlic|B-3, C-3, fiLflT'3)

SEE PAGE {figure 24) 3-12

PEDAL SOLO uNrr

General 3-21

Wiring Diagrams 3-22

Tuning 3-Z3

Block Diagrams (Figure 1 & 1 B) 3-24

Modai RT Schematic 3-25

Model RT-2 Schematic 3-26

Tube Voltages 3-Z8

Service Suggestions 3-29

Removing Parts 3-30

Parts Us! 3-31

Winng Diagrams Pedei Solo Gereraior 3-31

(Figure 4, 4B,&4C) 3-32

AMPLIFICATION SYSTEM

Pre-Amplitier Schematici

Modal A (Figure 1) 3-35

Models A & B (Figure 2 & 3) 3-36

ModelsA^B. C. D, Player & G

(Figure 4 & 5) 3-37

Made[sAV, 6V, BCV, CV. DV & RT

(Figure 6) 3-3B

Model E (Figure 7) 3-38

ModaJ E [Rgura B & 9) 3-39

POWER AHPUFIER SCHEMATICS PABE

(USED m TONE CABINETS)

Modefi A-20, A-40, B-40, C-40 (Figure 10) 3-40

Models A-20, A-40, B40, 0-40. D-ZO.

DR-2aG,0X-20 (Figure 11) 3-40

Models D-20. DR-20, B-40. Efl-20,

FR-20,f -40 (Figure 12) 3-41

Model»D'20.F-40,FR-40 (Figure 13) 3-41

Models DR-20, ER-20, FR-40 (Figure 14) 3-42

pL^dels H-40. HR-4D (Figure 15) 3-42

Models H-40. HR-40 (Rgura 16) 3-43

REVERB PREAMPLIFIERS SCHEMATICS

Models DR-20, ER-20 (Figure 17) 3-44

Models DR-20, ER-2G, FR-40 (Figure 18) 3-45

POWER AMPLIFIER SCHEMATIC
(USED IN TONE CABINETS)

MODELS H-40,HR-40 (Figure 19) 3-48

Models h-40, HR-40 (Figure 1 9B) 3-47

PRE'AHPUFIER SCHEMATICS

Models B'Z, C-2, RT-2 (Figure 20) 3-47

Models B-2, 0-2. RT-2 (Figure 20A) 3-47

POWER AMPLIFIERS SCHEMATICS
(USED l^ TONE CABINETS)

Modal JR-20 (Figure 22) 3-48

Model JR-20 (Figure 22A) 3-49

Model JR-20 (Figure 22B) 3-49

PREAMPLIFIERS SCHEMATICS

Models B-3. C-3, RT-3 (Figure 24) 3-50

POWER AMPLIFIERS SCHEMATICS
(USED IN TONE CABINETS)

Models PR-40. aR-40 (Figure 26) 3-50

Models PR-20 (Figure 28) 3-51

TONE CABINETS

Models PR-40, QR-40 3-52

Models PR-40, DR-40 (Figure 26A)

Schematic 3-53

Models PR-40, QR-40 (Figure 27A)

Schamatic later units 3-54

Models P-40. Q40 3-55

Models P-40, Q40 (rfgurs 29)

Schemetic 3-56

Modal PR 20 3-57

Model PR-20 Schamatic 3-5B

POWER AMPLIFIERS

{USED IN CONSOLES)

MODEL A-1 00 3-61

Schematic (Figure 32) 3-61

Wiring Dragram (Figure 33) 3-62

Model D-lOO (Figure 36) 3-6B

REVERBERATION AMPLIFIERS
(USED IN CONSOLES)

Modal A-100 (Figure 34) 3-63

(Figure 35) 3-64

(Rgure35A) 3-65

IMUBLE LOCATION 3 69

Trouble Shooting 3-69

Sectionalizmg Trouble 3-75

Trouble Shooting Chart 3-BO

Repepr S Oisassembfy of Vibrato Scanner 3-82

SECTION IV - ALIGNMENT PROCEDURES 41

Preset Panel Tone Selection 4-1

Alignment of Coil Assemblies 4-1

Adjustment of Percussion Cut-Otf Control 4-4

Adjustment of Intermittent or Non-flpereiing Keys , . , - 4-4

SECTION V - STAGE DATA AND FINAL TESTING 6-1

Detailed Theory of Operation 5-1

Replacement of Components 5-9

SECTION VI - PARTS LIST 6-1

B-3, C-3 6-5

Unique Parts for Other Models Lilted

In Service Manual 6'23

Tone Cabinets (PR-40, etc.) 6-31

MODEL A - AB

MODELS A & AS: (IS PRODUCTION JUNE 1935 TO OCTOBER 1938)
CABTNET SIZE: 4fi-l/2" WIDE, A7" HIGH, 38-1/2" DEEP.

FINISH:

MANUALS I

PEDAL
KEYBOARDS:

TONAL
CONTROLS:

EXPRESSION!

FEATURES

AC INPUT

HEI6HTI

AMERICAN WALKUT

SWELL AKD GREAT. 61 PLAYING KEYS EACH,

25-NOTE, RADIATING, DETACHABLE.

9 PRESET KEYS AND 2 SETS OF 9 ADJUSTABLE
HARMONIC DRAWBARS FOR EACH MANUAL; 2 AD-
JUSTABLE DRA^ARS (16' AND 8') FOR PEDALS

ONE EXPRESSION PEDAL CONTROLLING SWELL,
GREAT, AND PEDALS.

ONE TONE GENERATOR, ONE ADJUSTABLE
TREMULANT AFFECTING BOTH MANDALS AND
PEDALS EQUALLY.

APPROX. 3D WATTS, PLUS WATTAGE REQUIRED
BY TONE CABINETS.

AS ILLUSTRATED, APPROX, 359 POUNDS.

SERIAL NO, 2501 AND ABOVE USED LARGER WOODWORK CASE DE
SieNATED AS AB.

SEE B SERIES FOR CASE DIMENSIONS AND WEIGHT.

MODEL AB

CABINET
SIZE:

SAME AS MODEL A BUT ENCLOSED IN LARGER WOODWORK
ONE TONE GENERATOR, ONE ADJUSTABLE TREMULAKI AF-
FECTING BOTH MANUALS AND PEDALS EQUALLY.

WITH PEDAL KEYBOARD AND BENCH: AS-3/i" WIDE,
A9-1/2" DEEP, 46" HIGH.

MODEL BCt

(IN PRODUCTION DECEMBER 1936 TO NOVEMBER 1942),
SAME AS MODEL AB BUT WITH ONE ADDITIONAL GENER-
ATOR AND APPROPRIATE SWITCHING TO CREATE CHORUS
EFFECT.

FINISH:

WALNUT.

MODEL BV!

HOME MODELS BC, BV, BCV, B-2, AND B-3

FINISH:

(IN PRODUCTION APRIL 1946 TO DECEMBER 1949).
SAME AS MODEL B BUT EQUIPPED WITH HAMMOND VTB-
RATO PROVIDING THREE DEGREES OF TRUE VIBRATO
AND "OFF" POSITION, EFFECTIVE SIMULTANEOUSLY
ON BOTH MANUALS, TOGETHER WITH VIBRATO CHORUS
USABLE IN THREE DIFFERENT DEGREES AND "OFF".

WALNUT.

MODEL BCVi (IN PRODUCTION DECEMBER 1949 TO DECEMBER 1954).

SAME AS MODEL BC BUT HAS HAMMOND VIBRATO AND
VIBRATO CHORUS. NONE PRODUCED, CONVERTED BY
VIBRATO KIT ADDED AFTER 1945-

MOOa. B-2

FINISH:

SAME AS MODEL BV BUT WITH CONTROLS WHICH PRO-
VIDE VIBRATO OK EITHER OR BOTH MANUALS. ALSO
ADDITIONAL CONTROL FOR '^NORMAL" OR ''SOFT"

0\^RALL VOLUME.

(IN PRODUCTION DECEMBER 1949 TO DECEMBER 1954J

WALNUT.

MODEL B-3 (IN PRODUCTION JANUARY 1955 TO)

SAME AS MODEL B-2 BUT WITH HAMMOND PERCUSSION
FEATURE .

FINISH:

MANUALS :

WALNUT -CHERRY.

SWELL AND GREAT. 61 PLAYING KEYS EACH,

PEDAL

KEVBOARDl 25-NOTE RADIATING. DETACHABLE.

TONAL
CONTROLS;.

9 PRESET KEYS AND Z SETS OF 9 ADJUSTABLE HAR-
MONIC DRAWBARS FOR EACH MANITAL- 2 ADJUST-
ABLE DRAWBARS (16' AND 6") FOR PEDALS,

EXPRESSION: ONE EXPRESSION PEDAL CONTROLLING SWELL, GREAT

AND PEDALS,

AC INPUT: APPROXIMATELY 30 TO 50 WATTS, PLUS WATTAGE RE-
QUIRED BY TONE CABINETS.

WEIGHT!

AS ILLUSTRATED, APPROXIMATELY 425 LBS

l-l

MODEL B-A (IN PRODUCTIOH JANUAKY 1938 TO DECEMBER 1938),

THIS INSTRUMENT IS TONALLY AND ELECTRICALLY SIM-
ILAR TO THE MODEL BC CONSOLE DESCRIBED OK THE
PRECEDING PAGES.

IN ADDITION TO NORMAL PLAYING IT COULD ALSO

BE PLAYED WITH ROLLS SIMILAR TO A PLAYER PIANO,

FLOOR DrMENSlONS ARE ALSO SIMILAR TO THE BC WITH
A SOMEWHAT HIGHER BACK SECTION TO ACCOMODATE
PNEUMATIC ACTION.

> HOME MODEL B-A

CHURCH MODELS C, CV, C-2, C-3, D AND DV

MODEL C

CABTKH"
SIZE:

FINISH:

(IN PRODUCTION SEPTEMBER 1939 TO JUNE 1942).
SAME AS MODEL AB BUT WITH DIFFERENT STYLE
WOODWORK. ONE TONE GENERATOR, ONE ADJUST-
ABLE TREMULANT AFFECTING BOTH MANUALS AND
PEDALS EQUALLY,

MODEL D:

WITH PEDAL KEYBOARD AND BENCH:
47" DEEP, W HIGH.

WALNUT.

46-3/4" t.T:DE,

FINISH;

MODEL DV:

(IN PRODUCTION JUNE 1939 TO NOVEMBER 1942).
SAME AS MODEL C BUT WITH ONE ADDITIONAL TONE
GENERATOR AND APPROPRIATE SWITCHING TO CREATE
CHORUS EFFECT, SIMILAR TO MODEL BC-

WALNUT.

SAHE AS MODEL D BUT WITH HAMMOND VIBRATO, IN-
CLUDING VIBRATO CHORUS. SEE BCV.
NONE PRODUCED, KIT ADDED IN FIELD.

MODEL CV

FINISH:

MODEL C-2

(IN PRODUCTION SEPTEMBER 1945 TO DECDIBER 1949).
SAME AS MODEL C BUT EQUIPPED WITH HAMMOND VIB-
RATO, INCLUDING VIBRATO CHORUS*

WALNUT.

(IN PRODUCTION DECEMBER 1949 TO DECEMBER 1954).
SAME AS MODEL CV BUT WITH CONTROLS WHICH PRO-
VIDE VIBRATO ON EITHER OR BOTH MANUALS. ALSO
ADDITIONAL CONTROL FOR "NORMAL" OR "SOFT"
OVERALL VOLUME,

MANUALS! SWELL AND GREAT, 61 PLAYING KEYS EACH.

PEDAL
KEYBOARD!

TONAL
CONTROLS!

25-NOTE, RADIATING, DETACHABLE,

9 PRESET KEYS AND 2 SETS OF 9 ADJUSTABLE HARMONIC
DRAWBARS FOR FACH MANUAL; 2 ADJUSTABLE DRAWBARS
C16' AND 3') FOR PEDALS.

EXPRESSlONiONE EXPRESSION PEDAL CONTROLLING SWELL, GREAT,
AND PEDALS,

FINISH

WALNUT

MODEL C-3 (IN PRODUCTION JANUARY 1955 TO)

SAME AS MODEL C-2 BUT WITH HAMMOND PERCUSSION
FEATURE.

AC INPUTl APPROXIMATELY AO TO 60 WATTS, PLUS WATTAGE RE'
QUIRED BY TONE CABINETS.

WEIGKTs

AS ILLUSTRATED, APPROXIMATELY 450 LBS.

FTNISH:

WALNUT - OAK. LATER VERSION IN BOTH FINISHES
LESS QDATREFOIL.

1-2

U,S- SOVERW^ErjT PURCHASED EaUIPMENT MODEL G CONSOLE AMD TONE CABINET

The Model G consoles and tone cabinets were built for the
Government, and now will be found in use throughout the
United States and foreign countries In chapels of all ser-
vices, Officers Clubs, or recreation service buildings.

The console is identical to the Model D except for the
decorative woodwork and provision for detachable handles.

The tone cabinet [Model G-iO) contains two amplifiers and
four speakers mounted in a horizontal row and Is electri-
cally similar Co Model fl-40 tone cabinets, but has a re-
verberation control unit.

MODEL C-ZG, C-3G CONSOLES AND IIR-40G

These consoles are identical in appearance Co the C-2
and C-3 except that a monitor speaker Is located on the
lower left hand side.

The preamplifier in the C-2G Is designed to operate the
□lonitor speaker. In the C-3G the preamplifier is the
saBie as in the C-3. A small auxiliary amplifier drives
the monitor speaker- In both Models, B+ voltage from
the tone cabinet is required to make the monitor speaker
operative.

Produced from June I9il to NOVEMBER 1944,

The HR-40G is identical to the HR-40 except that it is
equipped with a standard 6 conductor cable which must be
used in conjunction with the C-2G console.

C-2G in production June 1952 to March 1953,
C-3G in production January 1955 to

CONCERT MODEL E

MODEL El (IN PRODUCTION JULY 1937 TO JULY 19A2-

CABINET WITH PEDAL KEYBOARD: 57" WIDE, 46-7/8" HIGH,

SIZE; 47-5/8" DEEP.

FIMSHt

MANUALS;

PEDAL
KEYBOARD:

TONAL
CONTROLS:

WALNUT

SWELL AND GRliAT, 61 PLAYING KEYS EACH.

32-NOTE, CONCAVE, RADIATING, DETACHABLE, BUILT
TO AGO SPECIFICATIONS.

9 PRESET BUTTONS AND 2 SETS OF 9 ADJUSTABLE HAR-
MONIC DRAWBARS FOR EACH MANUAL: FOR PEDALS - 4
NUMBERED AND LABELED TOE PISTONS 2 ADJUSTABLE
DRAls^ARS <16' AND 8") AND GREAT TO PEDAL S'
COUPLER

EXPRESSION! 2 EXPRESSION PEDALS, ONE FOR SWELL AND ONE

FOR GREAT AND PEDALS, VISUAL POSITION IN-
DICATORS OF SLIDING ROD TYPE.

FEATURES:

AC INPUT:

WEIGHT;

SEPARATE ADJUSTABLE TREMULANTS FOR SWELL AND
GREAT MANUALS, STANDARD MAIN AND CHORUS GEN-
ATOR UNITS; ON AND OFF SWITCH FOR CHORUS.

APPROXIMATELY 50 WATTS. PLUS WATTAGE REQUIRED
BY TONE CABINETS.

AS ILLUSTRATED^ APPROXIMATELY 579 LBS.

1-3

CONCERT MODELS RT, RT-2, AND RT-3

MODEL RT:

CABINET
SIZE:

FINISH

{IN PRODUCTION JULY 1949 TO SEPTEMBER 1949)-
EQUIPPED WITH HAMMOND VIBRATO PROVIDTSG THREE
DEGREES OF TRUE VIBRATO AND AN "OFF" POSITION,
EFFECTIVE SIMULTANEOUSLY ON BOTH MANUALS, TO-
GETHEE WITH VIBRATO CHORUS USABLE IN THREE
DIFFERENT DEGREES AND "OFF",

WITH PEDAL KEYBOARD; 57" WIDE, 46-7/S" HIGH
47-5/8" DEEP.

WALNUT.

MANUALS 1

PEDAL SOLO
SYSTEM!

SWELL AND GREAT, 61 PLAYING KEYS EACH,

PEDAL 32-NOTE, CONCAVE, RADIATING DETACHABLE^ BUILT
KEYBOARDS: TO AGO SPECIFICATIONS.

HAS PEDAL SOLO SYSTEM WITH SEPARATE VOLUME
CONTROL, PROVIDING FOLLOWING SOLO EFFECTS;
32-FnnT BOURDON, 32-FOOT BOMBARDE, 16-FOOT
SOLO, B-FOOT SOLO. 4-FOOT SOLO, 2 and 1-FOOT
SOLO. ALSO TABLETS FOR MUTE CONTROL AND
PEDAL ON.

MODETL fiT-2! (IN PRODUCTION NOVEMBER 1949 TO JANUARY 1955),

SAME AS MODEL RT BUT WITH CONTROLS WHICH PRO-
VIDE VIBRATO ON EITHER OR BOTH MANUALS, ALSO
ADDITIONAL CONTROL FOR "NORMAL" OR "SOFT"
OVERALL VOLUME.

FINISH:

WALNUT-

MODEL RT'3; (IN PRODUCTION JANUARY 1955 TO).

SAKE AS MODEL RT'-2 BUT WITH HAMMOND PERCUSSION
FEATURE.

TONAL
CONTROLS;

EXPRESSION'

AC TNPOTa

WEIGHT;

9 PRESET KEYS AND 2 SETS OF 9 ADJUSTABLE HAR-
MONIC DRAWBARS FOR EACH MANUAL; FOR PEDALS,
TWO ADJUSTABLE DRAWBARS (16' AND 8').

ONE EXPRESSION PEDAL, CONTROLLING SWELL,
GREAT AND PEDALS.

APPHOKIMATELY 110 TO 130 WATTS, PLUS WATTAGE
REOUIRED BY TONE CABINETS.

AS ILLUSTRATED, APPROXIMATELY 525 POUNDS -

FINISH:

WALNUT - OAK,

1-4

-1-

MODEL ;

A-100
A-101
A-102

(IN PRODUCTION 1959 TO 1965}. HOME STYLE CONSOLE. SAME AS C-3 BUT WITH
BUILT-IN SOUND SYSTEM INCLUDING REVERB CONTROL.

A-105

(IN PRODUCTION 1962 TO 1975). CHURCH STYLE CONSOLE, SAME AS C-3 BUT
WITH BUILT-tN SOUND SYSTEM INCLUDING REVERB CONTROL.

CABINET :

A-100

SIZE:

A-101
A-102
A-105

WITH PEDAL KEYBOARD AND BENCH 47-W WIDE, AS-Vi" HIGH, 43" DEEP

SAME AS MODEL C

FINISH :

A-100
A-101
A-102
A-105

RED MAHOGANY — LIGHT WALNUT

BROWN MAHOGANY - GRAY MAHOGANY - BLACK

LIGHT CHERRY - DARK CHERRY

LIGHT OAK - DARK WALNUT

OUTPUT :

27 WATTS - 2 AMPLIFIERS, 3-12" SPEAKERS

AC INPUT:

APPROXIMATELY 200 WATTS

1-4 A

MODEL :

D-100

(IN PRODUCTION 1963 TO 1969). SAME AS RT-3 BUT WITH BUILT— IN SOUND
SYSTEM INCLUDING REVERB CONTROL.

CABINET SIZE :

SAME AS RT

FINISH :

D-152

D-155

WALNUT
OAK

OUTPUT :

50 WAHS — 3 AMPLIFIERS, 2-12" SPEAKERS, 2-18" SPEAKERS

AC INPUT:

APPROXIMATELY 330 WATTS

WEIGHT :

AS ILLUSTRATED, APPROXIMATELY 543 LBS.

1-4 B

Mim

MODEL A-20! (IN PRODUCTION OCTOBER 1935 TO JTJLY 1939) »

CABINET
SIZE;

FINISH

weiGHT:
OUTPUT;
AC INPUT:

27" WIDE, 30*' HIGH, 15" DEEP

AMERICAN WAINUT

113 POUNDS

20 WATTS - 1 AMPLIFIER^ 2 - 12" SPEAKERS,

APPROXIMATELY 180 WATTS.

THIS SMALL DECORATIVE TONE CABINET IS USED FOH
HOMES, MORTUARIES, AND SMALL CHURCHES, SEATING
NOT OVER 100 PERSONS, WHERE A LIMITED AMOUNT
OF POWER IS REQUIRED,

MODEL A-20 TONE CABINET

HQ3>Q. A-40: (IN production October 1935 to October i947)

CABINET
SIZE;

FINISH:

WEIGHTS

OUTPUT!

AC INPUT:

26-1/2" WIDE, 28" HIGH, 19" DEEP

BLACK LACQUER.

155 POUNDS

iO WATTS - 2 AMPLIFIERS, 4 - 12" SPEAKERS

■

APPROXm\rELY 360 WATTS,

A NON-DECORATIVE, DOUBLE -STRENGTH CABINET, DE-
SIGNED FOR USE IN BANKS OF FOUR OR MORE, IN
LARGE INSTALLATIONS WHERE THE CABINETS ARE
CONCEALED.

MODEL A-40 TONE CABINET

1-5

MODEL B-40! (IN PRODUCTION NOVEMBER 1936 TO DECEMBER 19A7

CABINEJ SIZE: 36" WIDE, 36" HIGH, 28-1/2" DEEP

FIMSH
WEIGHT;
OUTPUT!
AC INPUT:

WALNUT STAIN

225 POUNDS

f*Q WATTS - 2 AMPLIFIERS. 4 - U" SPEAKERS.
APPROXIMATELY 360 WATTS-

A SEMI "DECORATIVE, DOUBLE -STRENGTH CABINET DE
SIGNED FOR USE IKDlVlDUALLy OR IN GROUPS.
THE B-40 IS FOUND DESIRABLE FOR MANY CHURCHES
Am FOR LARGE INSTALLATIONS, FOR IT MAY BE
USED APPROPRIATELY IN AUIOST ANY SETTING,

MODEL B^40 TONE CABINET

MODEL C-20!
M0DEL CR-20;

MODEL CX-ZO:

(IK PRODUCTION 1937 TO MARCH 19^2).

(IK PRODUCTION 1939 - 1942) EQUIPPED WITH
REVERBERATION UNIT.

(IN PRODUCTION JANUARY 1939 TO MARCH 1942)
EQUIPPED WITH ROTOR TREMULANT. SEE MODEL
CXR-20 FOR PICTURE OF THIS FEATURE.

MODEL CXR-20! (IN PRODUCTION NOVEMBER 1939 TO MARCH 1942)

EQUIPPED WITH ROTOR TREMULANT AND REVERBER-
ATION UNIT.

DIMENSIONS: 29" WIDE, 53" HIGH, iB-I/4" DEEP.

FINISH

WEIGHT:
OUTPUTS
AC INPUT:

HATCHED AMERICAN BUTT WALNUT AND ANTIQUE
BRASS HARDWARE,

153 POUNDS

20 WATTS, 1 AMPLI?TKR, 2 - 12" SPEAKERS

APPROXIMATELY 200 WATTS.

MODEL C-20, CX-2a, AND CXR-20 TONE CABINET

1-6

MODEL C-40i (IN PRODUCTION JimE 1936 TO DECEMBER 1937)

CABINET SIZE: 38" WIDE. 71" HIGH, 27-1/2" DEEP,

FiNISHi
WEIGHT:
OirrPUT:

AC INPUT;

WALNUT STAIN

313 POUNDS

UO WATTS - 2 AMPLIFIERS AND h - 12" SPEAKERS

APPROXIMATELY 360 WATTS.

THE C-iO CABINET HAS A WIDE VARIETY OF APPLICATIONS.
IT IS ESPECIALLY ADAPTED FOR USE IN ENCLOSURES WHERE
THE INDIRECT PROJECTION OF SOUND IS DESIRABLE. VERY
OFTEN THE CEILING AND FLOOR ARE THE ONLY "LIVE" OR
REFLECTING SURFACES AND THIS TYPE CABINET MARES USE
OF THERE,

THE C-AO CABINET IS USED INDIVIDUALLY OR IN CROUPS
OF TWO OR MORE.

MODEL C-40 TONE CABINET

MODEL D-ZO:

MODEL DX-20:

MODEL DR-20!

(IN PRODUCTION OCTOBER 1937 TO MARCH 1952),
TONALLY IDENTICAL WITH MODEL C-20, THE D-20
FILLS A NEED FOR AN INEXPENSIVE CABINET FOR
USE IN A WIDE VARIETY OF INSTALLATIONS V.TIERE
DECORATIVE QUALITIES ARE A SECONDARY CONSID-
ERATION.

(IN PRODUCTION OCTOBER 1938 TO JUNE 1942).
EQUIPPED WITH ROTOR TREMULANT.

(IN PRODUCTION AUGUST 1939 TO MARCH 1952).
EQUIPPED WITH REVERBERATION UNIT.

MODEL DXR-ZOl (IN PRODUCTION APRIL 1939 TO JUNE 1945).

EQUIPPED WITH ROTOR TREMULANT AND REVER-
BERATIOK UNIT.

CABINET SIZE! 28" WIDE, 56" HIGH. 16-3/4" DEEP.

FINISH:
WEIGKT!

OUTPUT:
AC INPUT!

FACE AND SIDES OF AMERICAN VALNUT.

149 POUNDS - D-20: 171 POUNDS - DR-20;
178 POUNDS - DXR-20,

20 WATTS - 1 AMPLIFIER, 2 - 12" SPFjUCERS

APPROXIMATELY 200 WATTS.

1-7

MODEL ER-20; flN PRODUCTION MARCH 19A7 TO DEGEMBEK 1950)

CABINET
SIZE:

FINISH:

WEIGHT:

OUTPUT:

AC IKPUTt

31" WIDE, 38-3/4" HIGH, IB" DEEP,

WALmJT,

lii POUNDS.

20 WATTS - 1 AMPLIFIER, 2 - 12^' SPEAKERS

APPROXIMATELY 200 WATTS.

THE ER-20 TONE CABINET IS ELECTRICALLY EQUIVALENT TO
THE DR-ZO TONE CABINET. HOWEVER, THE WOODWORK IS
DESIGNED FOR USE IN HOMES WHERE A MORE ARTISTIC CAB-
INET IS PREFERRED.

MODEL ER-20 TONE CABINET

ilii

iiiii

MODEL FR-40 ^™ PRODUCTION JANUARY 1948 TO DECEMBER 1957) »

CABINET SIZE: 32-15/16" WIDE; 39-3/16" HIGH; 28-3/8" DEEP.

FINISH;

tClGKri

OUTPUT I

AC INPLTT:

WALNUT STAIN

F-40 - 20a LBS. FR-40 - 228 LBS-

40 WATTS - 2 AMPLIFIEHS, 4 - 12" SPEAKERS

APPROXIMATELY 300 WATTS.

MODEL F-40 AND FR-40 TONE CABINET

THE F-40 REPLACES THE B-iO TONE CABINET- DIMENSIONS OF
THE WOODWORK HAVE BEEN ALTERED SO THAT A REVERBERATION
UNIT MAY BE ACCOMMODATED. WITH THE ADDITION OF THE
RE\'ERBERATION UNIT IT IS DESIGNATED AS FR.-40.

1-8

MODEL PR-40

MODEL QR-40

MODEL PR-40! (IN PRODUCTION FEBRUARY 1939)
CABINH" SIZE! 31-1/2" WIDE; 37-1/2" HIGH; 18" DEEP

FINISH:

WEIGHT!

WALNUT - OAK - CHERRY

130 POUNDS

HODfiL aR-40: (IN PRODUCTION JUKE 1939)

CABINET SIZE! 31" WIDE; 36-5/6" HIGH; 17-1/^" DEEP

WElGHTi

121 POUNDS

EQUIPPED WITH TWO 15" SPEAKERS FOR BASS TONES AND TWO
iZ" SPEAKERS FOR THE TREBLE TONES. THEY PROVIDE THREE
DIMENSION AMPLIFICATION WHICH CREATES A BEAUTIFUL RE-
VERBERATION EFFECT IN STEREO. THESE CABINETS FEATURE
THE NEW AND IMPROVED HAMMOND REVERBERATION CONTROL FOR
BOTH BASS AND TREBLE TONES. CONVENIENT OUTSIDE CONTROLS
MAKE IT EASY TO CHANGE THE DEGREE OF REVERBERATION FOR
EACH.

THE QR-40 IS ELECTRICALLY SIMILAR TO THE PR-40 BUT WITH
ITS UTILITY TYPE CABItfET IS ONLY USED WHERE APPEARANCE
IS NOT A CONSIDERATION, SUCH AS IN TONE AND REVERBERATION
CHAMBERS.

AC INPUT:

OUTPUT:

220 WATTS

50 WATTS E.I. A.

THE TREBLE DIRECT SPEAKER IS NORMALLY MOUNTED IN THE TOP.
IN AN UNUSUAL INSTALLATION UTTERE THE CEILING IS VERY LOW
OR CABINETS ARE STACKED OR RADIATION IS OTHERWISE RESTRICT-
ED, IT IS POSSIBLE TO MOVE THIS SPEAKER TO THE HOLE PRO-
VIDED IN THE FRONT. THE METAL DIFFUSER IN FRONT OF THE
SPEAKER MUST ALSO BE MOVED, ANT) THE WOODEN COVER MUST BE
ATTACHED UNDER THE TOP TO CLOSE THE HOLE.

I-II

1-12

THEORY OF OPERATION

The console of the Hammond Organ contains the entire tone-producing
mechanism, which is completely electrical in operation. Within it are
produced ail the tones and tone combinations of the organ. The electrical
waves are made audible, as music, by one or more tone cabinets containing
suitable amplifiers and loud speakers. The block diagrams (Figures 13 and
14) show the chief components of the instrument.

Electrical impulses of various frequencies are produced within a unit known
as the "tone generator'\ containing a number of "phonic wheels" or "tone wheels
driven at predetermined speeds by a motor and gear arrangement. Each
phonic wheel is similar to a gear, with high and low spots, or teeth, on its
edge. As the wheel rotates these teeth pass near a permanent magnet, and
the resulting variations in the magnetic field induce a voltage in a coil
wound on the magnet. This small voltage, when suitably filtered, produces
one note of the musical scale, its pitch or frequency depending on the number
of teeth passing the magnet each second,

A note of the organ, played on either manual or the pedal keyboard, generally
consists of a fundamental pitch and a nuiiiber of harmonics, or multiples
of the fundamental frequency. The fimdamental and eight harmonics available
on each playing key are individually controllable by means of drawbars and
preset keys or buttons. By suitable adjustment of these controls the player
is enabled to vary the tone colors at will.

The resulting signal passes through the expression or volume control and
through the preamplifier (where vibrato is introduced) to the tone cabinet.
Here reverberation is added electrically and a power amplifier feeds the
signal into loud speakers,

DESCRIPTION

A Hammond Ofgan console (Fig, 2} includes two manuals or keyboards: the
lower, or Great, and the upper, or Swell, and a pedal keyboard of 25 keys-
The concert models have a 32-key pedalboard and are constructed to A.G.O.
specifications. Various controls have appeared on different models. The op-
eration of these controls is covered in the following paragraphs,

STARTING THE ORGAN

FIGURE 1

To start the organ, hold the "start'' switch (Fig, 1)
in "on" position for approximately eight seconds.
Still holding it. push the "run" switch to "on" pos-
ition. After leaving both switches on for about four
seconds, release the start switch to return to its
normal position.

If the console is very cold, or if a frequency reg-
ulator is used, it may be necessary to hold the
start switch slightly longer.

1-13

1-12

THEORY OF OPERATION

The console of the Hammond Organ contains the entire tone-producing
mechanism^ which is completely electrical in operation. Within it are
produced all the tones and tone combinations of the organ. The electrical
waves are made audible, as music, by one or more tone cabinets containing
suitable amplifiers and loud speakers. The block diagrams (Figures 13 and
14) show the chief components of the instrument.

Electrical impulses of various frequencies are produced within a unit known
as the "tone generator", containing a number of "phonic wheels" or "tone wheels
driven at predetermined speeds by a motor and gear arrangement. Each
phonic wheel is similar to a gear, with high and low spots, or teeth, on its
edge. As the wheel rotates these teeth pass near a permanent magnet, and
the resulting variations in the magnetic field induce a voltage in a coil
wound on the magnet. This small voltage, when suitably filtered, produces
one note of the musical scale, its pitch or frequency depending on the number
of teeth passing the magnet each second.

A note of the organ, played on either manual or the pedal keyboard, generally
consists of a fundamental pitch and a number of harmonics, or multiples
of the fundamental frequency. The fundamental and eight harmonics available
on each playing key are individually controllable by means of drawbars and
preset keys or buttons. By suitable adjustment of these controls the player
is enabled to vary the tone colors at will.

DESCRIPTI ON

A Hammond Organ console (Fig. 2} includes two manuals or keyboards: the
lower, or Great, and the upper, or Swell, and a pedal keyboard of 25 keys.
The concert models have a 3Z-key pedalboard and are constructed to A.G. O.
specifications. Various controls have appeared on different models. The op-
eration of these controls is covered in the following paragraphs-

STARTING THE ORGAN

FIGURE 1

To start the organ, hold the '^start" switch (Fig. I)
in ^'on'' position for approximately eight seconds.
Still holding it, push the "run" switch to "on" pos-
ition. After leaving both switches on for about four
seconds, release the start switch to return to its
normal position.

If the console is very cold, or if a frequency reg-
ulator is used, it may be necessary to hold the
start switch slightly longer.

1-13

THE

CONCERT MODEL

HAMMOND

ORGAN

THE

HOME MODEL

HAMMOND

ORGAN

FIGURE Z

1-14

PRESET KEYS

At the left end of each manual are twelve keys identical to the playing keys
except reversed m color. (Fig. 3). These are replaced by twelve nuinbered
buttons on the Model E console.

When a preset key is depressed it locks
down and is released only when another
is depressed. The exception to this is
the cancel key at the extreme left, which
serves only to release any key which
may be locked down. Only one preset
key is used at one time. If by mistake
two are depressed and locked, they may
be released by means of the cancel key.

Each preset key, with the exception of
the cancel key and the two adjust keys
at the extreme right of the group, makes
available a different tone color which
has been set up on the preset panel lo-
cated inside the console- These tone
colors are set up at the factory in
FIGURE 3 accordance with a standard design which

has been found to best meet the average organist' s requirements. They may be
changed, if desired, by removing the back of the console and changing the preset
panel connections in accordance with instructions on a card located near the pre-
set panel.

When either adjust key is depressed, the organ speaks with whatever tone color is set
up on the harmonic drawbars associBted with that key. The percussion effect on Models
B-3, C-3, RT-3, A-100 & D- 100 is introduced when the upper manual "B' preset key is
depressed (see ''percussion" also).

HARMONIC DRAWBARS

Each console has four sets of harmonic drawbars, two for each manual. Fig-
ure 4 shows one group of harmonic drawbars, by which the organist is enabled

aTH HARfc*ONtC

6TH HARMONIC
5TK HARMONIC
4TH HARMONIC
3RD HARMONIC

FIGURE 4 ONE HARMONIC DRAWBAR GROUP

to mix the fundamental and any, or all, of eight different harmonics in various
proportions. The third bar from the left controls the fundamental, and each of
the other bars is associated with a separate harmonic. If a drawbar is set all
the way in, tht' harmonic it represents is not present in the mixture.

Each drawbar may be set in eight different positions by the organist in
addition to the sileni position. Each position, as marked on the drawbars ,
represents a d^ff^Tent degree of intensity of the harmonic it controls. When
drawn out to position 1. the harmonic it represents will be present w^ith
minimum intensity, wh<"n drawn out to position 2. with greater intensity,
and so on up to position S.

A tone color is logged by noting the numerical position of the various
drawbars- For instance, the tone set up on Figure 4 is known as tone
34 630 SZIO. After a tone is so logged it rnay be made available again by
setting the harmonic drawbars to that number.

The drawbars in earlier consoles have distinct intensity positions with
-silent spots between them. Later consoles are equipped with "continuous
contact" drawbars which move smoothly with no interruption m tone.

HARMONIC DRAWBARS FOR THE PEDALS

In the pedals the harmonic resources have been combined into two drawbars
which may be used separately or in combinations. When the left drawbar is
used emphasis is given to the lower harmonicSi and similarly the higher
harmonics are emphasized when the right drawbar is used. The pedal draw-
bars are located between the two sets of manual drawbars.

PEDAL TOE PISTONS - MODEL E CONSOLE

FIGURE 5

tour pedal toe pistons are located to
the left of the expression pedals. Num-
bers one and two of these pistons are
pedal presets. The third is a Great-to-
Pedal coupler, which makes the pedals
speak with whatever 8 foot tone is set
up on the Great manual. The left pedal
drawbar may he used with the coupler
to add 16 foot tone. The fourth piston
connects the pedals to the two pedal
drawbars.

Lighted piston indicators are pro-
vided on the left aide of the console
just above the Swell manual. Each
timt' a toe piston is depressed, the
proper indicator is automatically
illuminated so Che organist always
knows which toe piston is depressed.

1-15

PEDAL SOLO UNIT - MODELS RT. RT-2, RT-3. D-IOO

A pedaf solo unit is incorporated in the concert Models to provide a series of bright pedal solo
tones in addition to the usual pedal accompaniment tones available on other models. The pedal
solo tones, generated by a vacuum tube oscillator circuit, are controlled by a volume control knob
and eight tilting stop tablets located at the right end of the Great manual (Fig. 5). One tablet turns
all the pedal solo tones on or off and the others provide various pitch registers and tone colors.
The pedal solo unit is independent of the efectromagnetic tone generator and can be turned off
without affecting the remainder of the organ.

NORMAL ' SOFT VOLUME CONTROL
(Models B-2, B-3, C-2. C-3. RT'2. RT-S, A-100, D-100)

This control (Fig. 3} is a tilting tablet which supplements the action of the
expression pedal. In "'soft" position it reduces the volume of the whole
instrument. It is particularly useful when playing in a small room or when
the organist wishes to practice without disturbing others,

CHO R U S CQNT ROL
(Models BC. BCV, D, DV, E)

On these models an extra generator known as a chorus generator will be
foxind. To use the tones generated by this unit at will, one extra black
drawbar has been added which operates a switch located on the generator.
The drawbar labeled "chorus" is located at the right-hand end of the con-
sole. (Fig. 6)

When the organ is played with the chorus drawbar pushed in (the "off'' position)
it operates m exactly the same way as though no chorus were included. Pulling
he drawbar out (to the "on" position) instantaneously adds the ensemble or
-lorus t-ffecl to whatever is being played. Actually it adds a series of slightly
sharp and slightly flat tones to the true tones produced by the main generator.
The resulting electrical wave contams a complex series of undulations which
enhance the pleasing effect of many tone qualities, notably string and full
organ combinations.

The chorus control should not be confusi^d with the "vibrato chorus" effect,
described under "vibrato". The two effects are similar musically, but are
produced by completely different means.

EXPRESSION OR SWELL PEDAL

The swell pedal, located in the customary position, is operated by the right
foot and with it the volume of the organ may be controlled over a wide range.
It operates on the two manuals and pedals equally; that is to say. once the
manuals and pedals are balanced, they retain their relative balance over
the entire swell pedal range.

Two expression pedals are provided for the Model E Console. Both are
equipped with adjustable clamps to regulate the tension and the distance
through which they move. Adjustable pedal indicators, operated by wires
from the rheostat box. are located at the extreme right side of the console
above the Swell manual.

ECHO SWITCH

Located above the starting and running switches
on some consoles is the "echo switch" (Fig. 6).
With this switch it is possible to use two tone cabi
nets and have either cabinet or both speak, de-
pending on the position of the switch. Generally
one tone cabinet is placed rather distant from
the console and is called the "echo organ". This
feature can be added to a Hammond Organ by
installation of an "Echo switch kit".

FIGURE 6

1-16

TREMULANT

The tremulant or tremolo is a periodic variation in intensity of all tones
without change in pitch. It is produced by a variable resistance driven by
the motor of the main tone generator, and is controlled by a variable resistor
in shunt. When the tremulant control is turned as far as possible to the left,
the tremulant is entirely off- As it is turned to the right (clockwise) the degree
of tremolo gradually increases until it reaches a maximum at the extreme right
position. The while dot marker on the knob indicates at a glance the degree of
tremolo present. Two tremulant controls are used on the Model E console, one
for each manual. These are controlled by separate levers located on the console.

The tremulant is not incorporated in models having vibrato.

VIBRATO

The vibrato effect is created by a periodic

raising and lowering of pitch> and thus is fun-
damentally different from a tremolo, or loud-
ness variation. It is comparable to the effect
produced when a violinist moves his finger
back and forth on a string while playing,
varying the frequency while maintaining
constant volume.

The vibrato mechanism includes an electrical
time delay line, which shifts the phase of all
tones fed into it- A rotating scanner, mounted
on the main tone generator, picks up success-
ive signals from various line sections. These
signals represent various amounts of phase
shift, and the combinai-ion of signals produces
a continuous frequency variation.

FIGURE 7

When the ''vibrato chorus" switch (Fig- 7) (Models AV, BV, BCV, CV.
DV, and RT) is pushed to the left, normal vibrato is obtained with the
vibrato switch in positions 1, Z, or 3. When the lever is pushed to the
right a chorus or ensemble effect, combining foundation organ tone with
vibrato tone, is obtained. The center position of this switch is not intended
to be used. No harm will result from leaving the switch in this position, but
reduced volume will be obtained.

Models B-2. B-3, C-2, C-3. RT-2. RT-3. A-IOOA 0-100 have the "seleclivevibraio" feature
which makes the vibrato effect available on either manual separately or on both together Two
lilting tablets [Figure 3) control the vibrato tor the Iv^'O manuals, while the rotary switch selects
the degrees of vibrato or vibrato chorus effect. The "Great" tabiet controls the vibrato for the
pedals as well as for the Great manual.

The vibrato is not present on models having the tremulant

PERCUSSION

The Percussion teaUjre {Models B-3, C-
3, RT'3, A-100 & D-lOO) is controlled by
four tilling tablets (Fig. 8) at the upper
right Side of the manuals. Percussion is
available only on the upper manual and
only when the 'B' preset key Is
depressed. The four tablets (from tefl to
right) select Percussion on of off, normal
or soft Volume, fast or slow Decay, and
second Of third Harmonic lone quality-

Percusaion tones are produced by
borrowing the second or third har-
monic signal from the correspond-
ing manuai drawbar, amplifying it,
returning part of the aignal to the

eame drawbar, and conducting the balan-ce of the signal through push-pull con-
trol tubes where its decay characterica are controlled.

FIGURE 8

The Percussion signal is then combined with the signal from the manuals
after the vibrato but before the expression control. The control tubes are
keyed through the eighth harmonic key contacts and busbar.

I-I7

TONE GENERATOR

The main tone generator furnishes 82 or 91 different musical frequencies,
depending on the console modeL It includes a tone wheels magnet, and coil

for each frequency. Mounted on top of the generator are tuned filters to
insure purity of the tones,

PREAMPLIFIER

The preamplifier is located in the console. Several types have been used
in the various console models. Some obtain their plate voltage from the
power amplifier through the console -to - cabinet cable, while others have a
self-contained power supply,

TONE CABINETS

Tone cabinets are made in a number of models differing in size, finishj and
power output. The numbt-rs 20 and 40 in the model designations indicate the
nominal pow^t'r output in watts. Each tone cabinet includes one or two power
aniplifier^ and two or more speakers.

Cables of special design are used to connect the console to the tone cabinet
or cabinets,

REVERBERATION CONTROL

Tone cabinets having the letter R within the model designation are equipped
with the Hammond Reverberation Control. This is an electro -rnechanical
device designed to supply reverberation for installations that are accousti-
cally "dead" or have insufficient natural reverberation. A portion of the
musical signal is delayed by passing through fluid-damped coil springs and
then combined with the direct signal. By adjustment of the amount of
delayed signal the reverberation characteristics of large or small enclosures
may be simulated. A tone cabinet having this unit must be handled in accord-
ance with directions on the instruction card in order to avoid damaging the
unit or spilling the fluid.

ROTOR TREMULANT

Tone cabinets having the letter X in their model designation contain a drum
rotor inount*^d above the speakers and driven by a small motor. Rotating in
the path of sound from the loud speal^ers, it produces the effect of a periodic
voluzne and pitch variation in all tones of the organ.

A switch for controlling its operation can be mounted on the tone cabinet, or
an additional cable w^ith a switch located at the console may be used.

When a console having the Hammond Vibrato is connected to this type cabinet;
use of the rotor tremulant is not recommended.

1-18

POWER AMPLIFIER

A- 100

A twelve watt amplifier is mounted on the lower shelf of the console. It receives
the signal from the Preamplifier and increases it in power to drive the two 12^^
speakers .

D-100

A fifty watt three channel amplifier (bass with reverberation, treble, treble
with reverberation) together with its independent power supply is located on
the lower shelf of the console. It receives the signal from the preamplifier
and furnishes power to drive the Z-12^' speakers and Z-8^' speakers.

REVERBERATION SYSTEM

A-lOO

To the left of the amplifier are the reverberation amplifier and reverberation unit
A portion of the output signal of the power amplifier passes through the reverber-
ation unit to the reverberation amplifier and this drives a third IZ" speaker
housed within the console. The degree of reverberation heard can be regulated by
rotating the knob marked "Reverberation Control" shown in Figure 5.

D-100

To the left of the pedal solo generator is the Hammond Reverberation unit. Sig-
nals from the preamplifier are applied to the ^'treble with reverberation" channel
of the power amplifier and are heard from the 8'^ speaker located to the right
of the player.

In operation, an electrical signal from the reverberation drive channel is ap-
plied to the driver unit in the reverberation device which then converts the
electrical signal into mechanical energy. This energy is transmitted through
springs to a pickup unit w^here a part of it is converted back to electrical
energy. The remaining portion is reflected back to the driver and again back
to the pickup at a time interval determined by the spring lengths. This trans-
action continues until the signal energy is reduced to one millionth of its ori-
ginal value. The transfer time from driver to pickup and the reflections within
the systen^ itself produce the reverberation effect.

1-19

SECTION n

ACOUSTICS - THE PART THEY PLAY
IN HAMMOND ORGAN INSTALLATIONS

INSTALLATION S IN GEN ERAL

The proper ln?Eallj.tion of a. H^mmund tir^Lin requires the careful observance of

four primary rules:

1. The 0Tg:m should furnish AMPLE POWER.

2, The sound energy from the orfi^n should be EVENLY DISTRIBUTED.

3, The console and lone cabinets should be so located m relation to each other and
to the audience, choir, soloist, etc., that a PROPER TONAL BALANCE is
accomplished.

4. The organ tone should be PROPERLY REVERBERATED.

The observance of these rules with due consideration to the particular use for which
the instrument is required will Insure the best possible installation m any type of
enclosure. These rules will be discussed in detail in the following pages.

P OWER

There are so many factors which have a bearing on the amount of power or sound energy
necessary for best musical results in a t^iven enclosure that an accurate formula for
determinins^ the required power in all cases would be too cumbersome for everyday use.
Experience has shown that it is very seldom that too many tone cabinets are specified.
Therefore> if there is doubt as to the sufficiency of tone cabinets for any Installation
Lt is reasonably safe to double this amount. This will j:reatW improve the musical
quality of the instrument and elimmate overloading of the speakers. Some of the factors
which have a bearing on the amount of tone cabinet equipment required in any enclosure
are the size and shape of the enclosure, placement of tone cabinets, amount and location of
sound-absorbing materials including persons present in the enclosure. The use for which
the organ is desired also has a bearinfc on requirements; for example^ an organ to be
used primarily to support congregational singing would require more tone cabinets
than one that is to be used mainly for accompaniment of soloists or light entertainment.

The following conditions in an enclosure, therefore, usually indicate that more than
an average installation may be required:

i. When the area of the boundaries of the enclosure is great in proportion to the volume
of the enclosure- Thus, an enclosure of irregular shape having numerous alcoves, etc.,
would require more lone cabmets than one of cubical shape.

2. When the tone cabinets are located in a position where considerable sound absorp-
tion takes place before the music reaches the listener. A poorly designed or construct-
ed organ chamber is an example.

3- When acoustical correction materials are used on walls or ceiling, when heavy drapes
are present and carpets are used for floor covering.

4. When seating capacity is high for the size of the enclosure. For practical purposes
an open window is considered as an area of 100 percent absorption of sound. A single
person absorbs about as much sound as four square ieet of open window. Therefore, an
audience of 1,000 people will have the effect on music volume of an open window area of
4.000 square feet as compared with the volume heard when the enclosure is empty. To
offset this absorption, a disproportionately greater amount of tone cabinet equipment
must be used.

DISTRIBUTION

The sound energy from the organ should be distributed as evenly as possible throughout
the enclosure- In order that this may be accomplished, it is important that the sound
be distributed in the auditorium above the listeners and that a large percentage of the
sound reaching the listener is by numerous reflections from the walls and ceiling.
Direct projection as well as direct reflection from the speakers should not reach the
listener. Focusing effects of curved surfaces such as barreled ceilings often cause
difficulty in sound distribution unless the tone cabinet is so located as to reduce the
direct sound energy that reaches these surfaces.

It must be remembered that although sound is reflected In a manner similar to light,
the reflecting surlace must be large in relation to the wave length of the sound.
Therefore, a reflecting surface of a given size will reflect sounds above a certain
frequency, while sounds of lower frequency will tie diffracted or spread out. To re-
flect fully the lower tones of the organ a reflector thousands of square feet in area
ia necessary. This, together with the fact that different materials absorb sounds
of certain frequencies more than others explains why identical tone colors produced
in different enclosures will sound very different to the ear.

BALAN CE

The placement of console and tone cabinets should be carefully planned so that the

following conditions are fulfilled:

1. The organ should sound as loud or slightly louder to the organist at the console
than it does to the audience. This allows the organist to accurately judge the musi-
cal effect he is producing and make any necessary corrections before the audience
appreciates the need for them. It also reduces the tendency of playing too loud which is
usually evident when the organist hears the or^an at a lower level than the audience.

2. The organist should hear the organ and the choir with the same relative loudness
that the audience hears them, otherwise a perfect tonal balance between organ and
choir from the organist's point of hearing will result in an unbalanced effect as heard
by the audience. When we refer to the choir we also include instrumental groups or
soloists who may have occasion to perform in conjunction with the organ.

3. The tonal equipment of the organ should be so located that the choir, while singingi
has adequate support from the organ when played at accompaniment volume. They
should noln however, hear the organ so loudly as to have difficulty in singing with it-
Good lonal balance and ease of performance should result if the average distance
between choir and tone cabinets is about the same distance as between tone cabinets

and organist.

4. The audience should hear the choir and the organ as a balanced ensemble, and
the tone cabinets should be so placed that the choir voices will not te obscured by
the organ tones.

2-1

REVE K BEIL^TION

Reverberation is the prolongatian or persistence of sound by reflection, what we
usually mean by "echo". It is measurable by the interval of time required for the
sound to decay to inaudibility after the source of the sound has been stopped. It is
present in a varying decree m all enclosures and most types of music are more
pleasing to the ear when accompanied by a certain amount of reverberation. It is
also the most important single factor to be considered in planning an organ installa-
tion as proper reverberation makes it easier to attain all of the other requirements
necessary for a perfect installation.

In a Hammond organ installation, the proper amount of reverberation may be se-
cured in three ways:

1. By the successive reflections of the sound by the boundaries of the auditorium,

2. By the Hammond Reverberation Control.

3. By placm^ the tone cabinets in a chamt>er, the boundaries of which cause the
or^an tones to reverberate before reaching the auditorium.

REVER BERATION IN THE ALTDIT ORIUM

The reverberation that results from the successive reflections of sound back and

forth by the boundaries of the auditorium itself is most desirable from the installa-
tion engineer's point of view, (By auditorium we mean any audience room such as a
church or concert hall.)

In a reverberant auditorium less power is necessary and problems of sound distribu-
tion are greatly simplified and. therefore, the best possible musical results are
usually obtained as a matter of course. Unfortunately, however, the reverberation
characteristics of an auditoriuna usually are not alterable by the installation engineer,
and he must accept them, good or bad as the case may be.

A reverberation time of one second when a two-thirds capacity audience is present is
usually sufficient if reasonable care is taken in locatmg the organ equipment for proper
distribution and balance although a slightly longer reverberation time is otten desir-
able. It must be remembered that the reverberation time in any enclosure is greatly
reduced when an audience is present. In jjeneral, the higher the ceiling of the audi-
torium> the less effect the preseflce of an audience has on the reverberation time;
however, this effect is always considerable. If the natural reverberation in the
auditorium is insufficient for best musical results from the organ, another method
must be used to properly reverberate the organ tones.

HAMMOND REVERB E R ATION CONTROL

The Hammond Reverberation Unit provides an effective means of securing proper
reverberation in all types of installations where the natural reverberation in the
auditorium is insufficient. Experience has shown that best installations in homesT
radio studios, mortuaries, and small churche;^ include a tone cabinet equipped with
reverberation control, it may also be used to improve the effectiveness of the organ
In auditoriums where considerable natural reverberation is present, but where this
natural reverberation is characterized by an objectionable echo occurring after the
organ tones have seemingly ceased. The Hammond Reverberation Unit will not elimi^
nate an echo or reduce the natural reverberation time, but will often make this natural
reverberation more pleasing to the ear by "filling in' that period between the time the
organ tones seem to cease and the echo occurs. The Hammond Reverberation Unit
will not add to the reverberation time in auditoriums already having excessive natural
reverberation. As the reverberation unit is connected to the electrical system of the
organ and provides reverberation at the source of sound rather than after the sound
comes from the speakers, it allows the installation engineer to place the tone cabinets
for best results in balance and distribution without the necessity of compromise for
reverberation considerations. The use of this device also eliminates the necessity
of costly reverberation chambers, and by allowing the tone cabinets to be so located
a.s to minimize sound ener^jy losses, a saving in the amount of necessary power equip-
ment is often effected. A further advantage is that the reverberation time may be
regulated for best musical results after the organ is installed.

With the use of the Hammond Reverberation Unit a good organ installation should
always result if the tonal equipment is placed to give even distribution and proper
tonal balance.

REVERBERATION CHAMBERS

When it is desired to conceal the organ tone cabinets and there is adequate space
available, a properly designed reverberation chamber may be very effective in supply-
ing reverberation for the organ tones. In many cases, however, the space allotted for
use as a reverberation chamber is anything but ideal, and often, because of structural
limitations, little can be done to improve the effectiveness of the chamber other than
to make minor corrections. The following principles of reverberation chamber design
are given for guidance in properly evaluating the good and bad characteristics of a
given chamber and in making such changes as will improve the effectiveness of the
chamber as much as possible.

SIZE

As the reverberation time increases as the size of the chamber increases, the chaml>er
should be as large as possible. Experience has shown that practically the only ex-
ceptions to this rule are when the shape of the chamber may be improved by reducing
its size or when the tone opening cannot be made large enough in proportion to the size
of the chamber. For best musical results the chamber should be at least 800 cubic feet
in volume. The dimensions of the chamber are in most cases ideal if they are in the
ratio of approximately 2:3:4 1/2, A chamber of equal volume but more cubical In
form would have a longer reverberation time^ while a chamber of less cubical form
would have a shorter reverberation time; however, dimensions in the above ratio usually
are most desirable. Chambers of complex shape or chambers of regular shape whose
greatest dimension is more than three times the least dimension should be avoided ,

2-2

CI4ART SHOWING SIZE OF TONE OPENING REQUIRED
FOR REVERBERATION TIME OF ONE SECOND

FOR CHAMBERS WITH DIMENSIONS IN RATIO OF Z : 3 : 4.5

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FIGURE 1.

CONSTRUCTION AND FINISH

All boundaries of a reverberation chamber should be of exceptionally rigid construc-
tion. Concrete or heavy tile is ideal. If the chamber is to be of frame construction
the studs should not be over fourteen inches on centers. Lath should be very securely
nailed and the plaster should be hard and given a smooth finish coat.

TONE OPEN I NGS

The reverberation time of an organ chamber is greatly influenced by the size of the
tone opening. For a chamber of given dimensions, the reverberation time is increased
as the area of the tone opening is reduced, A large chamber, therefore, may have a
large tone opening and still furnish sufficient reverberation, whereas a small chamber
might require a very small opening. A chart is shown in Figure 1, giving the area of
tone opening lequired to furnish one second reverberation time when the volume of
the chamber is known. This chart is for chambers with dimensions in the ratio of
2:3:4 1/2 only; however, in practice the areas of tone opening shown are generally
satisfactory.

The tone opening should be located in the largest wall surface of the chamber if
possible, and preferably near the center of the wall area,

INSTALLATION AN D M AINTENANCE

The organ must be connected to a regulated-frequency source of the
voltage and frequency specified on the name plate. If the frequency is
not regulated the pitch of the organ will be irregular.

When a console is set up for operation the anchoring must be loosened so that
the generator will float freely on its spring suspension systen]. No damage
will result if this is not done, but the console "svill sound noisy, and the same
is true if the anchoring is loosened but the console is not level. If the console
is to be moved a long distance the anchoring should be tightened during such
moves.

Several different types of anchoring have been employed and instructions for
loosening and tightening the generator in any particular consoleare given on
the instruction card contained in the bench which accompanied that console.

Each power amplifier has anchoring which should be loosened on installation
and tightned for shipping. If the cabinet has a reverberation unit, it should be
locked before moving the cabinet and the fluid should be removed as instructed
on the card attached to the tone cabinet.

The tone generator is lubricated by putting oil into cups inside the console. It
is recoinmended that each cup be filled three-fourths full, {1 tablespoon) once
a year» using only the oil recommended for this purpose.

2-3

CABLES

Each console is shipped from the factory with cables sufficient for an
ordinary installation having a single tone cabinet. It has a 15 foot Z conductor
line cord for connecting to an AC wall outlet, and a 35 foot console -to-cabinet
cable (6 conductor or 5 conductor, depending on the console model) to connect
to the first power amplifier. In case the console is located an unusually long
distance from the tone cabmet, additional 6 or 5 conductor cable must be
ordered. If the console has an echo switch, a b conductor cable of the required
length must be ordered separately to connect it to the echo tone cabinet. (See
"Echo Organ Wiring'', on the following page).

For Installations having two or more tone cabinets, cable suitable in length
must be secured to connect betv-een cabinets. Each power amplifier has a 6
pole input plug and a 5 pole coupling receptacle for connecting additional amplif-
iers.

TYPES OF CABLES USED

6 Conductor c onsole -to -cabinet cable used only <::>x\ mode ls A. B , B A , BCj
BCVTBV , C,CV , D,DV.E,G , RT. This is used only between these models
of consoles and the first power amplifier, and has a 6 pole plug at one end and
a 6 pole receptacle at the other. It consists of two AC wires, two grid (signal)
wires, a B plus wire to carry plate current from the first power amplifier to
the console preamplifier, and a ground (signal return) conductor^ which is
actually a shield over the B plus wire. This cable is especially designed for
use with the Hammond Or^an and is approved by the Underwriters* Laboratories
for that purpose ,

S^Conductor c onsole -to-cabinet or cabinet-to-cabmet cable. This is identical
to the 6 conductor cable except that it has no shield and one end has a 5 pole pliig
instead of a 6 pole plug. It has no B plus conductor, the fifth wire being used for
ground. It IS used for carrying power and signal between amplifiers, since a B
plus connection is never needed beyond the first power amplifier; to connect an
echo cabinet, since in this case also no B plus connection is required; and as a
console -to -cabinet cable for models where the console preamplifier has its own
power supply, In case 5 conductor bulk cable is not available, a 5 conductor cable
assen^.bly niay be made from 6 conductor bulk cable, using the shielded wire for
ground and leaving the shield disconnected. NOTE: 5 conductor console -to-cabinet

cable IS used with Models B-2. B-3, C-2, C-3, RT-2. RT-3, A-l 00 8. D-1 00

3 Conductor cabinet -to-cabinet cable. This is used for carrying only the
signal between amplifiers, and is used for connecting cabinets when external AC
power vircuits are employed- It is standard 3 conductor indoor telephone cord
and has 5 pole plugs on both ends. A cable may be made up with a number of
plugs along its length in order to connect several cabinets together. This wire
can be secured from your local electrical jobber,

Z Conductor li ne cord. This supplies AC power to the console and has a
standard attachment plug on one end and a standard attachment receptacle on

the othe r .

Z Conductor cabinet power cord^ This is used to furnish AC power to additional
power amplifiers, when the signal is supplied through a 3 conductor signal cable.
It has a standard attachment plug at one end and a 6 pole receptacle at the other.

All cables with the exception of the 3 conductor may be ordered in lengths
as shown on current price list, with or without connectors attached- Figure 10
shows how all connectors are wired.

For permanent installations, when the cables are to be installed in conduit,
special "Jones" fittings manufactured by the Cinch Manufacturing Company are
obtainable through your electrical supplier. Those recommended for console
location are;

1-S406-CCE 6 prong socket

1 -P406-WP 6 prong plug with wall plate

For each tone cabinet location:

1-P4C6-CCE ks prong plug

1 -S406-WP 6 prong socket with wail plate

BLOCK DIAGRAMS

Figure 1 is a simplified diagram showing how the console is connected to
a single tone cabinet or group of cabinets drawing not over 620 watts input.
This is the maximum AC power which can be supplied through the console
without damaging the console switch or wiring. The name plate on each cabinet
shows its wattage rating.

2-4

If the lone cabinet power requirerrjents exceed 6Z0 watts, some of the cabinets
must be supplied from a separate AC source as indicated in figures 2 and 3.
Figure Z is the preferred method, employing a relay to turn on the additional
cabinets. The relay must have a coil of the samke voltage and frequency rating
as the organ, and must have contacts suitable for carrying the an^ount of power
drawn by the additional cabinets. Allen -B radley Bulletin 700 relays are suitable
for this purpose and may be obtained from your electrical supplier.

When the AC power is supplied separately to additional cabinets, as in figures
2 and 3, a 3 conductor cable is sufficient to carry the signal between cabinets.

DETAILED WIRING DIAGRAMS

Figures 4, 5, and 6 are detailed versions of figure 1 . In figure 4 the console is
connected to one tone cabinet having a single amplifier, and figure 5 shows connec-
tions to a cabinet with two power amplifiers, connected together by a 5 conductor
coupling cable. Additional amplifiers, up to a rnaximum of 620 watts AC input,

may be connected as shown in figure 6,

Figure 7 is a detailed diagram of the arrangernent in figure 2. The 3 conductor
cable carries signal to all cabinetSj while each cabinet has its own AC power cord.
In this case the 6 pole input plug in each additional cabinet is used for power input
only, and the signal is fed into the 5 pole coupling receptacle.

A switch may be connected in place of the relay contacts to convert this circuit
to the arrangement of figure 3.

ECHO ORGAN WIRING

Some desirable musical effects may be secured by an "echo" tone cabinet in-
stalled at a location sonne distance from the main cabinet or cabinets. As indicated
in the block diagram, figure 8, an echo switch on the console controls only the tone

cabinet signal circuits, and ail cabinets remain energized so that they will sound
instantly when desired. Figure 9 shows the cable connections required.

REVERBERATION EQUIPMENT

Some types of tone cabinets have reverberation units and reverberation
preamplifiers built into them. In this case, see the instruction card attached to
the cabinet for correct cable connections. V/hile there are several different
styles of wiring, it will be found that every cabinet has a 6 pole input plug and a
5 pole output receptacle for connecting additional amplifiers. Some reverberation
preamplifiers employ a special detachable coupling cable, wired as shown at the
bottOiTi of figure 10.

In reverberation-equipped tone cabinets type CR-2D, DR-ZO, ER-ZO, FR-40,
and G-40, reverberation is applied to all organ frequencies. In this case only
one reverberation unit is required for any installation, no rnatter how many tone
cabinets are used. The reverberation unit should be in the cabinet which is con-
nected directly to the console, in order that reverberated signal may be supplied
by it to all other cabinets.

In Multi-channel tone cabmets type JK-20, HR-40, KR-40, PR-ZO, PR -40
and QR-40 a reverberated signal is not available to drive succeeding cabinets. For
this reason an installation using several such cabinets must have a reverber-
ation unit in each cabinet if it is desired that reverberation be present in all
cabinets .

It is not recommended that Multi -channel cabinets be driven by a reverber-
ated signal from a preceding cabinet because irregularities in the bass response
of the reverberation system may be emphasized by the bass amplifier channel.
In case one of these cabinets is to be used with one or more reverberation cabinets
of othe r type s , it should be connected directly to the console , with the othe r
cabinets following it in the usual way,

Further information on types of reverberation equipment will be found in
the section dealing with this item.

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2-8

TECHNICAL SECTION
MAIN GENERATOR - GENERAL DESCRIPTION

Each Hanrmond Organ console has a main generator within, it, and in
some cases, depending on the model, a chorus generator. This section
describes the main generator, illustrated below.

Figure 1

The main generator assenibly consists of the generator proper, a shaded
pole induction motor for starting, anon-self-starting synchronous motor
for driving the unit after it is started, and either a tremulant switch
mechanism or a Vibrato Scanner mounted on the synchronous motor. The
entire assembly is mounted on two long steel angles which also provide
the means of mounting the tone generator in the console. The method of
mounting is such as to minimize the transmission of vibration from the
tone generator to the console.

A drive shaft, resiliently coupled to the synchronous running motor, extends
the entire length of the generator- Twenty-four driving gears, two each of
twelve sizes, are mounted on this shaft, and the drive shaft itself is divided
into several sections connected by flexible couplings. The starting motor
is mounted at the end of this drive shaft, opposite the synchronous motor.
Section 7 describes the starting procedure.

The main generator proper is a long structure in which are mounted 48
rotating assemblies, each consisting of a shaft and two discs known as
tone or phonic wheels. These assernblies are coupled resiliently to the
drive shaft. Each of the driving gears engages fwo bakelite gears
a-^sociated with opposite rotating assemblies (See Figure 2). These
"bakelite gears rotate freely on the shafts with the tone wheels, and are
coupled to their respective assemblies by a pair of coil springs. There
are 12 sizes of bakelite gears, corresponding to the 12 sizes of driving
gears. Thus 4 of the tone wheel assemblies, each with 2 tone wheels, run
at each of 12 speeds,

Each tone wheel is a steel disc about 2 inches in diameter, accurately
machined with a definite number of high and lew points on its edge
(See Figure 3). Each high point on a tone wheel is called a tooth. The
number of teeth on each of these tone or phonic wheels, in conjunction
with the speed at which the tone wheel is revolving, determines the fre-
quency of the tone generated.

Each driving gear, with its two bakelite gears and four tone wheels, runs
in a separate compartrnent magnetically shielded from the rest by steel
plates which divide the generator into a series of bins.

All four tone wheels m any one compartment run at the same speed. The
individual tone wheel shafts are mounted in bearings made of a special
porous bronze and each of these bearings is connected to the oiling system
by a cotton thread from the oil trough. Thus, oil from the trough is carried
by capillary action to all bearings, penetrating thern and lubricating the
actual bearing surface. The drive shaft and both motors are lubricated in
a similar manner. It is very important to use the recommended grade of
oil regularly, as it is essential to the proper operation of the organ that the
generator be well lubricated. If oil of varying grades is used, it is likely
that the generator may be sluggish in starting, and in time the threads may
gum up and prevent the proper flow of oil.

The two spring couplings on the motor shaft, the flexible couplings
between sections of the drive shaft, and the tone wheel spring couplings
all contribute to absorbing variations in motor speed. The synchronous
motor does not deliver absolutely steady power, but rather operates
with a se"ries of pulsations, one with each half cycle. If the tone wheels
were rigidly coupled to the motor, this slight irregularity would carry
extra frequencies into each tone wheel. In addition, "hunting" is suppressed
by the resilient couplings and inertia men^bers of the synchronous motor
proper.

2-9

Associated with each tone wheel is a magnetized rod about 1/4 of an inch
in diameter and 4 inches in length, with a coil of wire wound near one end
(See Figure 3). The tip of the magnet at the coil end is ground to a sharp
edge and mounted near the edge of the tone wheel. Each time a tooth passes
this rod it causes a change in the magnetic field which induces a small
voltage in the coil, the frequency being determined by the number of teeth
and the wheel speed,

Sm.aH coils are used on the higher frequency magnets and larger coils
on the lower frequencies. It is found that large pole pieces are needed on
the low frequency magnets to give good frequency output, but is it necessary
to use smaller ones on the high frequencies to prevent excessive iron losses.

Some of the coils have copper rings mounted on them for the purpose of
reducing harmonics. As these are used only on fairly low frequency coils,
the eddy current loss in such a ring is small for the fundamental frequency
of that coil, but high for its harn^onics. This has the effect of reducing
the relative intensities of any harmonics which may be produced by ir-
regularities in the tone wheels. The wheels are cut so to give as nearly
a sine wave as possiblej but the generated voltage seldom reaches that ideal
condition, since even a change in the air gap will change the wave form. The
tip of each magnet, as well as the edge of each tone wheel, is coated with
lacquer to prevent corrosion, for, should oxidation set in, "the change in
tooth shape would introduce irregular frequencies.

Locations of the various n^agnet and coil assemblies are shown in Figure 4.
They are identified by their frequency numbers, and the broken line between
any two nuinbers indicates that these two frequencies are supplied by one
tone wheel assembly.

Each magnet is set at the factory with the set screw partially loosened,
while observing an output mieter. Experience has shown that the niagnets
seldom need adjustment and that setting them without proper equipment involves
danger of damaging both magnet and w^heel. Therefore it is not recommended that
the service man attempt this adjustment.

As a means of eliminating any vagrant harmonics that rriay be present, there
are filters consisting of small transformers and condensers associated with
certain frequencies. The transformers have a single tapped winding, and this
tap is grounded, so one side, which is connected to the corresponding magnet
coil through a condenser, forms a resonant circuit for the fundamental

frequency of that coil. This tends to emphasize the fundamental and suppress
hartnonics.

Locations of these transformers are shown in Figure 5 and 6. They are
aliio shown in schematics in section 2,

These transformers and condensers are mounted on the top of the
generator assembly. The transformers are mounted at an angle, thus
minimizing interference between themi. The cores of the transformers

are made of a special iron, and the number of laminations used is adjusted
to secure the proper inductance. Wires from the magnet coils connect to
the transformers, and wires from the transformers lead to the terminal

strip on the generator.

This terminal strip carries the output frequencies of the generator, which
are arbitrarily numbered from 1 to 91 in order of increasing frequency.
This frequency numbering is continued throughout the instrument. In some
models the frequencies are not in order on the terminal strip, and Figures
5 and 6 indicate the arrangement for different models- Several terminals
at the right end are grounded to the generator frame and serve to ground
the manuals and pedals.

Transformers and condensers are not used below frequency 44, but a
length of resistance wire shunts each generator. Frequencies 44 to 48
have transformers only, while both transformers and condensers are used
for frequencies 49 to 91 except in the case of Model A consoles numbered
below 2179, which do not have condensers for frequencies 49 to 54 inclusive.

Two condenser values are used - 0. 255 mfd for frequencies 49 to 34, and
0. 105 mfd for frequencies 55 to 91. The transformers are all different.
Each transformer is matched to its condenser and any replacements are
supplied as matched pairs by the factory.

2-10

There are several types of generators in use and the foilo\^^ing information
will aid the service technician in identifying the console on which work is
being performed.

91 Frequency Generator

Model A serial No. 1

2676

Model B serial No. 4000 - 10, 549

Model D serial No. 1

Model E serial No. 8000

3143

8663

Model C serial No, 1

1247

Player consoles

serial No. 9000

9Z09

The number of tone wheels on the above models is 91, and 5 blank wheels
are used to maintain the balance of the rotating units. There are twelve
wheels with two teeth, one to operate at each of twelve speeds, and
similarly twelve have four teeth, twelve have eight teeth, twelve have
sixteen, twelve have thirty-two, twelve have sixty-four, twelve have one

hundred and twenty-eight and seven have one hundred ninety-two. An
assembly with a two-tooth wheel also has a thirty-two tooth wheel which
generates a frequency four octaves above the other. The four and sixty-four
tooth wheels go together, as do the eight and one hundred twenty-eight tooth

wheels. The twelve sixteen tooth wheels are mounted with seven one hundred
ninety-two tooth wheels and the five blank wheels. In this last group the high
frequency is not four octaves above, but is four octaves less five semi^tones
above the lower.

This arrangement gives a total of 91 frequencies that are connected to
corresponding terminals on the generator, and then to the manuals and
pedal switch. In all cases, as mentioned above, the generator must be
used with corresponding manuals and pedal switches and other types of
generators cannot be substituted.

82 Frequency Generator

Model A serial No. 2677

2711

Model D serial No. 3144

17, 074

Model B serial No. 10, 550 - 17, 074 Model E serial No. 8664

8739

Model C serial No- 1248 - 17, 074 Model G serial No. 4101

7349

Player consoles serial No. 9210 only.

In the above consoles, frequencies #1 to 9 have been omitted from the
generator, and only 82 generator terminals are used. Similarly, there are
only 82 tone wheels and magnets in the generator instead of 91- Blank wheels
replace the nine two-tooth tone wheels formerly used to produce frequencies

1 to 9.

This generator change accompanies a wiring revision in the manual and pedal
switches which makes the frequencies from 1 to 9 unnecessary. Generators
having but 82 frequencies are easily identified by a blank space on the terminal
strip at the left of the ground terminals* The first terminal at the left of this
space is terminal #10.

91 Frequency Generator with Cornplex Tone Wheels
Model BV serial No. 17075 - 29737

Model CV serial No. 17075

302S7

Model RT serial No. 1001

1201

Model B-2 serial No, 35000 - 40303

Model C-2 serial No. 35001 - 40459

Model RT-2 serial No. 1300 - Z150

in the above consoles, the original two-tooth wheels in the generator have been
replaced with twelve two-tooth com^^lcx tone wheels, which supply a funda-
mental tone that is enriched with the odd-number harn:ionics. Both manuals
and pedal switch are wired differently and are therefore not interchangeable
with earlier models.

2-11

91 Frequency Generator with complex tone wheels and narrow cover

Model B-Z serial No. 40304 and above

Model C-2 serial No. 40460 and above

Model RT-2 serial No. 2151 and above

All Models'
A-100, B-3, C-3
D-100

This generator has twelve complex tone wheels and is identical to the one
above except for the generator cover. Because the output terminals of this
cover are not in order of frequency (See Figure 6) this type of generator is
not interchangeable with the one above.

Model M Tone Generator

The generator used in Spinet Models M and M-2 has 86 tone wheels and
differs from other niodels in several other respects. The twelve complex-tone
wheels are different in shape froin those used in other models, and the
generator-to-rnanual cable connects directly to the filter transformer terminals.
For details, refer to Model M or M-2 service book.

When ordering replacement generators be sure to state model and serial
number of consoles, as generators are not interchangeable.

Note: Consoles have been made equipped with 115 volt 25 or 50 or 60 cycle and
230 volt 50 cycle generators. If the owner is contemplating moving to a
location having a different frequency of current, the complete generator must
be changed^ Where voltage changes only are encountered, step-up or step-
down transformers will be necessary.

Generator Anchoring

When a console is set up for operation the anchoring rnust be loosened so that
the generator will float freely on its spring suspension system. No damage
will result if this is not done, but the console will sound noisy, and the same
is true if the anchoring is loosened but the console is not level. If the console
is to be moved a long distance the anchoring should be tightened during such
moves.

Several different types of anchoring have been employed and instructions for
loosening and tightening the generator in any particular console are given on
the instruction card contained in the bench which accompained that console.

TOBlE WVJtE-L^

nAtr^iy

CO(L

O^ntviTt ttfcw

CCLl.

r^fcirtir

BfcHCLat GEAR

Oft*¥IHS GEAR

SECTION OF MAIN GENERATOR
Figure Z.

2-12

UAQ^CT

ONF SlOt OF COIL CftOUWDED

CO<L OUT^T TERMINAL

TO'VE WHEEL

CO>L

TONE GENtHATOR

BACK ViEW or MAIN GENERATOR

FRONT VTEW OF MAIN GENERATOR

GENERATOR MAGNET LOCATIONS

Fig^rt 4,

(WiUTtbers shown Art frtqutnty numbers)

FILTER

OUTPUT 1"t.R*^iEHAi, Fptg^StV ^J^_^^ABE.Pi

FIGURES -MA'.M GENERftTOR COVER

WODEL^ ft,&T&Ci6VfcC.C^,t,nv,e, AMP RT

OF TflftKSfOHWEa.S

MOTO^ Etal

FILTER TRJ^P^^FoRHtfti

CD1iJH>4S£R5

^ ^ -. ^ ^ ■■ M Tr_ « ^ 4 Afl flF 2J_Sr M M 14 M *1 73 fl H ift J? .1 4fl gi <^5 ^ B S? 7^ U ^? 75 rs Si ^ U B 44 » U 1

It ii fi H 9 4^ 2t tZ Z 5*. II fi7 T a* 54 34 ta 41 77 [-P 11 14 ^ IC *-fc rV &3 a fl^ flO ?d S* 17 33 15 41

CJiJTPuT TtffMINAL FBt^fiUfV NUM&f-ft^ '

Figures -maim generator cover

MODEL B-2 5Efi^AL Nu^^flER ^03D4 AhiO A.&OVE
hICCfL C £ f^EF^l^L hJUMC^R 4Q44C Af-Ji) ABOvE

2-13

CHORUS GENERATOR
(Used in models BC, D, E, and G )

The purpose of the chorus generator is to add a series of slightly
sharp and 'slijjhtly flat tones to the true tones produced by the main
generator. The resulting electrical wave contains a corrtpl^'x senes
of undulations which enhance the pleasing effect of many tone qualities,
notably string and full organ combinations. It should be noted that no
chorus effect is produced on frequencies below 56.

The frequencies covered by the chorus generator are nunibers 56 to
91 inclusive on the main generator. The difference in frequf^ncy between
the main generator and either flat or sharp tone is .8% for frequencies
56 to 67 and .4% for frequencies 68 to 91. It is necessary that a lesser
percentage of frequency difference be present in the higher register
in order to avoid too rapid undulation.

The chorus [generator assen^bly, like the main j^enerator, has a drive
shaft with twenty-four brass t^ears. Each gear drives a single asserribly
consisting of two tone y^heels. The drive gears vary as to the number
of teeth, and the tone wheels operate at twenty-four different speeds.
This generator has forty -eight tone wheels, each with a separate mag-
net and pick-up coil. Of these tone wheels, twenty-four are single and
twenty-four are double (see Figure 1). The double tone wheels consist
of two discs wilh different nurribers of teeth mounted on one brass hub.
The single wheels are electrically connected in pairs, each pair being
BO connected as to have the sarne effect as one double wheel.

Fijjure Z is a complete wiring diagram for connections between main
and chorus j^enerators, and Figure 3 is a back view of the chorus
generator indicating the frequency number of each magnet.

<z<Z'a. ^<z<z<z r^<z<>^<4.o^<z ^'a.<z<z r^<a<z<z ^^

NOTE: NUMBERS SHOWN ON FILTER TRANSFORMERS

ARE FREQUENCY NUMBERS.

CABLE CONNECTIONS
TO CHORUS GENERATOR

Figure i.

o
-I
o

©@©@©@@©@®©®0

©@@@©@©©

®@©©@@©©

@@©©@@@@

@ @ @ @

DftfVE SII^FT —

BRJ^SS G£Ail

IKlL'nLE! TOHt WHEEL

BAKELITE G3_^

5JNCt-E TONE WHEEL

CHORUS CErfEBATOR
TDhE WKEEL A^LrhiBLV

2-14

a>CK VIE* or CHOHUS GENERATOR

( NUMBERS SHOWN ARE FREQUENCY NUMBERS)

CHORUS GENERATOR MAGNET LOCATIONS

Figure 3

CONSOLE POWER WIRING
{Main and Chorus Generators)

Starting and Synchronous Motors

A shaded pole induction motor is used for starting the generator and
is located at the right end of the generator as viewed from the back.
The rotor of this motor will slide endwise when current is supplied
and engage a pinion on its shaft with a gear on the generator driving
shaft, bringing the tone generator up to slightly greater than syn-
chronous speed.

When the organ is started, the starting switch is turned on and held
for about 8 seconds while the starting motor brings the system up to
speed. The "run" switch is then turned on. This switch simultaneously
connects the synchronous motor and introduces a resistor in series
with the starting motor (Figure l), thus reducing its driving power.
With a braking action of the synchronous motor and a loss of power
of the starting motor, the system slows to synchronous speed and
the synchronous motor begins to carry the load. A period of about
B seconds should be allowed for this to take place, after which the
starting switch may be released. The starting switch springs back
to the "off" position, and turns off the starting motor, which is
disengaged from the rotating shaft by a spring-
It should be noted that the synchronous motor can supply power only
at synchronous speed, Thereforei if for any reason the system fails
to reach synchronous speed it will not continue to run after the start-
ing switch is released. Failure to start properly is usually due to
increased oil viscosity and may be overconne by an increase in start-
ing time.

As the schen-iatic diagram (Figure 1) indicates, the "run" switch in its
"off" position shorts out the wirewound resistor attached -o the line
panel. If the "run" switch is defective in its '"off*" position, the generator
will not start because this resistor will be permanently in series with
the starting motor. Before assuming that there is anything amiss with
the motors, short out this resistor and start the generator in the norrnal
manner. If the generator operates satisfactorily, replace the "run" switch

The "run" switch on all consoles is a two-circuit switch, but types of

switches having two different terminal arrangements have been used, as

shown in Figure 2. When replacing a switch, observe the wiring of the

old switch and check the connections of the new switch with an ohmmeter.
Note that black and blue are connected in the "on" position, and yellow

and brown are connected in the "off" position, no rnatter which type of

switch is used.

STARTING MOTORS

CHORUS

MAIN

u
<

OFF

<
I

m
o

Q
Z
<

-J

-START" rvVXAA*-
SWITCH

SYNCHRONOUS MOTORS

MAIN

CHORUS

A A

OFF

"RUN"

SWITCH

WIRE WOUND RESISTOR

U5V, LINE, 1 GEN. - ISO OHMS
115V. LINE, 2 GEN. - 125 OHMS
230V. LINE, 1 GEN. - 1000 OHMS
230V. LINE. 2 GEN. 500 OHMS

FIGURE I
SWITCH AND MOTOR CIRCUITS

2-15

BI^CK

TEL-LOW

B1.UE

OFF

BHOMfN

SWITCH USED IN MODEL
M AND M-Z CONSOLES
AND ],N EJ^RLY CONSOLES
OF OTHER MODELS

BHOWH

flLJ\CK

YELLOW

OFF
BLUE

SWITCH USED IN
LATE MODEL S. C.
B-Z, C-l. ETC.

FIG 2

T»WO TYPES OF BUN' SWITCHES

WIRE WOUND
RESISTOR

GOO GOO

STARTING MOTOR YELLOW

'HUN" SWITCH YELLOW

"S TART^' SWITCH BROWN ,
'■RUN" SWITCH BROWN

OGGG GOG GGO

STARTING MOTOR GREY

PREAMPLIFIER GREY

SYNCHRONOUS MOTOR l^RED, I-BLACK OR BLUE

FIG, 3

"RUN" SWITCH BLUE

SYNCHRONOUS MOTOR

1-RED 1-BLACK OR BLUE
PREAMPLIFIER BLUE

"START'' SWITCH BLACK

"RUN" SWITCH BLACK

LINE CORD BLACK

I^INE CORD GREY

LINE PANEL (EARLY CONSOLES)

2-16

WIRE WOUND
RESISTOR

o o o o o o

STARTING MOTOR

YELLOW
"RUN" SWITCH - YELLOW

''START" SWITCH fie "RUN"

SWITCH-BROWN
STARTING MOTOR BROWN OR GREY

PREAMPLIFIER BLACK OR GREY

PEDAL LIGHT AND HEATER BLACK

SYNCHRONOUS MOTOR 1-RED, i-BLACK OR BLUE

@ @

BLUE- "RUN" SWITCH

SYNCHRONOUS MOTOR

1-RED, 1-BLACK OR BLUE
BLUE' PREAMPLIFIER

PEDAL LIGHT & HEATER - BLACK
BLACK - ''START" SWITCH

BLACK "RUN" SWITCH

BLACK-LINE CORD

BLACK OR GREY LINE CORD

FIG, 4

LINE PANEL (LATER CONSOLES

Manuals and Pedals

Fipire 1

A TYPICAL MANUAL CHASSIS ASSEMBLY (Model B-2)
For Description of Controls See Section 2,

Manual Chassis Assembly - Models A, AV. B. B A. EC. BCV, BV. C,
gy, b. DV. G. GV, RT.

The manual chassis assembly, Fig. 1, which includes the upper and lower
manuals and the preset panel, has a terminal strip under each manual made
up of 82 or 91 terminals, depending on the generator being used, to
accommodate the frequencies from the tone generator assembly. Each manual
has 61 playing keys, 9 preset keys, and 2 adjust keys, each of which operates
nine small bronze contact springs with precious metal points ( See Figure 2).
When a key is pressed these points make contact with nine busbars extending
the entire length of the manual. The busbars also have precious metal contact
surfaces.

The nine contact springs under each key carry the nine harmonics of the
particular note with which they are associated (See Figure 3) and are
connected by resistance wires to the proper terminals on the termmal
strip. Therefore all key contacts are alive whenever the generator is
running. See schematic diagram of console in Section 2,

RESISTANCE MIRE

PAUA Pnni ALLOY
ACT WIfiE

KEY CONTACT SPRING

Figure 2

A CTUATOR FQK Q NE KEY
I

ITH HARVDKEC

tTH HAR^T■:■^ r

4TH HAAMONIC

4T4 HARMONErn

JPD HARMONlt;

Z«p KARi*ON]C

f UNDAr^lENTAL

SUB ^ftP HARMONfC

SUB rUNDAME^JlAi

I I
I I

I ■
I I

F I

I ■

TOP CONTACT SPRlJ^C
TOP BUSBAFI

BOTTOKf CONTACT SPRlHC
BOTTOM BUSBAR

AHRANCEMENT Of MANUAl- CONTACTS

Figure 3

2-17

When a p!ayinp key is pressed, its nine frequencies are impressed on the
nine busbiirs of the manual. As there are no wires connected to the.se bus-
bars, a pretict or adjusi key mu.st be depressed before any circuit can be
completed. Each preset and adjust key has nine contacts exactly like those
of the playing keys. These keys have a locking and trip mechanism which
allows only one key to be in operation at one time. The key at the extreme
left end of the manual is a cancel key, with no contacts, which releases any
preset or adjust key that happens to be depressed. (Also see Page 15)

The adjust keys, A# and B, are connected by flexible wires, color-coded for
easy identification, to the corresponding; nine drawbars. The drawbars slide
over nine busses which arc connected to taps on the matching transformer.
These correspond to different intensities of sound as shown by numbers on
the drawbars.

The two left groups of drawbars are associated with the upper manual, while
the two right groups work in conjunction with the lower manual. In each case
the A^ adjust key controls the lelt hand group of drawbars for that manual.

The nine preset keys, from C# to A inclusive, are wired to flexible leads
terminating at the preset panel in the back of the console, where the
various tone colors are set up by connecting each wire to a screw terminal
corresponding to the desired intensity of the harmonic. These screw
terminals are located on 9 horizontal bars, each representing: a certain
intensity for all wires attached to that bar.

The drawbar busses and the preset panel bars are connected in parallel to
taps on the primary of the matching transformer.

Manual Chassis As^^emb ly - Models B-2, C-2 and RT-2

In these selective vibrato consoles, the individual manuals are the same as

in other models but the drawbar assembly is different, having three tilting
tablets ("Vibrato Swell On-Off," "Vibrato Great On-OIf" and 'Volume Soft-
Normal') at the left of the vibrato switch knob.

The selective vibrato feature requires that the preset panel and drawbar
assembly be divided and connected to two matching transformers, each
serving one manual. See schematic diagram in Section 2. The Great, or
lower manual, matching transformer also serves the pedal keyboard.

Continuous-contact drawbars are used in later consoles of this type. They
operate more smoothly and require less accuracy of adjustment than the
earlier type having nine definite positions or steps. Each one has two
contacts connected together by a one ohm resistor, so that at least one qi
the contacts touches some bus at all times and there are no *dead spots^
in the drawbar motion. The resistor avoids short-.circuiting adjacent busbars.

Manual Chassis Assembly - Models B-3, C-3, RT-3, A-100 & D-lOO
The above description also applies to these models, but the start and run
switches are relocated to provide room for four tilting tablets which control
the Percussion feature, described in Secclon lO.All manual chassis assem-
blies are equipped with continuous contact drawbars.

Manual Chassis Assembly - Bfodel E

The appearance of the ijpper> or swell manual, and the lower, or great manual.
is the same as on other models except that numbered pistons are used instead
of preset keys. These pistons operate in exactly the same manner, and produce
the same effects, as do the preset keys on the other models.

The internal wiring of the manuals is to a large extent the same as in other
models, but the use of two tremulants requires that the preset panel and
drawbar assembly be divided, and that two matching transformers be used,
each manual t)eing connected to its own matching transformer.

Manual Busbar Shifters

The precious metal contact surfaces of the key contacts and busbars are
not subject to corrosion, and the manuals are sealed to exclude dust as far as
possible. In spite of these precautions an occasional particle of dus! many
lodge on a contact and cause the note to be scratchy, noisy, or silent, and for
this reason a busbar shifting mechanism is provided on each manual to slide
the busbars endwise and thus provide a fresh contact surface. The busbar
shifter for each manual is a slotted stud near the right end of the manual as
viewed from the back of the console [see rear view of console in Section 2
for location).

If any note becomes scratchy or silent, it should first be struck 15 or 2l
times in a rapid staccato manner to loosen the dirt. This will usually dis-
lodge the particles and clear the note.

In case this procedure is not effective, the busbar shifter for that manual
may be adjusted by turning the stud about two turns in either direction. Tt
may sometimes be necessary to hold down the offending key while turning
the busbar shifter, in order to wipe the contact clean.

2-18

Model A consoles below serial number 995 are not equipped with busbar
shiiters except in cases where the manual chassis and pedal switch have
been rebuilt. Full information on this rebuilding may be obtained from the
Organ Service Department of the Hammond Organ Company.

Manual Wiring - Models A, AV. B. BA, BC. BCV. BV, C, CV, D, DV, E, G,

Figure 4. a wiring chart for the playing manuals, will be helpful in tracing
difficulties associated with the generator or manuals. All playing manuals are
wired alike from drawbar 2 to drawbar 8 inclusive, but the wiring of drawbars
1 and 9 varies. Column "A" shows the wiring of drawbar 1 for consoles above
serial number 17075; column "B" refers to all consoles having 82 note gen-
erators; and column "C" is the wiring used in all earlier consoles. Column
*d" shows wiring of drawbar 9 for Model 'A™ consoles below serial number
2500 and Model "BC" console below 5076; column *E ' refers to all later
consoles.

These variations in wiring are designed to match the different type of
generators described in the section covering lone generators, and therefore
the various types are not interchangeable.

Manual Wiring - Models B- 2. B-3, C-2. C-3. RT-2, RT-3, A-100 & D-IOO

The key circuit wiring for these models ts the same as for previous consoles

above serial number 17075, and so columns 'a' and 'e' in figure 4 apply.

Manual Wiring - Model M Series

The frequency chart in this section does not apply to these models because
they have fewer keys on each manual and have a slightly different arrange-
ment of harmonics. Full details will be found in the service booklets cover-
ing these models-

■a"

■b'

■c'

'D*

■e*

{See lelC)

(3«e text)

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2-19

FRBQUB14CT13 DSED EN UAHIJAE^
Flcufv 4

PEDAL SWITCH ASSEMBLY
Figure 5

Pedal Switch Assembly - All Models with 25 Note Pedal Keyboard

The pedal switch {shown in Figure 51 is similar in construction to the manuals
except that only four busbars are included instead of nine. Each of the 25
pedals actuates a double set of contact springs, making eight contacts avail-
able for each note. Each note consists of a fundamental and number of
harmonics, no sub-harmonics being used. The pedal contact springs are
connected to terminals by resistance wires similar to those used in the manual
assembly, and a cable connects these terminals through a wiring tube to the
proper terminals on the generator terminal strip.

Four colored wires carry the pedal tones from the busbars to the pedal draw-
bars. In some models the wires are connected first to a resistor panel on the
back of the manual assembly. A small choke coil and resistor mounted on the

manual assembly are wired to the lower drawbar (see Figures 8» 9, 10, 11) and
serve to filter out any higher harmonics or transients which might be present
in the lower pedal frequencies.

Early consoles used only seven contacts on each pedal (see Figure 6) and were
wired so that any harmonic would appear on only one pedal drawbar (Figures
8 and 9), Later consoles use all eight contacts (Figure 7) and employ a
system for mixing the 16 ft. and 8 ft, tones (Figures 10 and 11). The harmonic
arrangement of the contacts is also different in these later units.

Figure 13 is a wiring chart for the pedals, showing the frequency numbers
appearing on each pedal contact. The variations in wiring make the pedal
switches match the different types of generators described in the section
covering tone generators, and therefore the various types are not inter-
changeable.

Specific pedal wiring of any console can be determined by obtaining the serial
number and referring to Figures 8 to 11, Included in these sketches are refer-
ences to Figure 13 wiring chart«

2-20

ONE PEDAL

6TH HARMONIC
-iTH HARMONIC
2ND HARMONIC
FUNDAMENTAL

TOP CONTACT SPRINGS

8TH HARMONIC
STH HARMONIC

3RD HARMONIC

NOT CONNECTED

BOTTOM BUSBAR

ARRANGEMENT OF PEDAL CONTACTS

MODEL A CONSOLES SERIAL NOS. 1 To 2499

MODEL B AND BC CONSOLES SERIAL NOS. 4000 To 5075

Figure 6

lOTH HARMONIC

6TH HARMONIC

£ND HARMONIC

FUNDAMENTAL

TOP CONTACT SPRINGS

12THHARMONJC

8TH HARMONIC

4TH HARMONIC

3RD HARMONJC

BOTTOM BUSBAR

ARRANGEMENT OF PEDAL CONTACTS
ALL OTHER CONSOLES WITH 25 PEDALS

Figure T

2ND P£DAL DRAW&AR

iTt

1ST PEDAL DRAWSAff

FILTER
10 OHMS I

wmES TO PEDAL 5WITCH

FIGURES PEDAL CIRCUITS

MODEL A CONSOLES SERIAL NO. I TO 2499

MODEL B AND SC CONSOLES SERIAL NO. 4000 TO 507S

(for pedal ^m^MG SEE FfGuRE ll^OLUMNS i,4.5,6,7.ft,9)

OS 2013

I — |— AV^V^-'

I aooHMs

SOHtbriS

RESISTOR PANEL

z
o

2
O

a:
<

a
z

JNO PEDAL ORAW&A

I5T PEDAL DRAWBAR

^^i

OS 2014

-WIRES TO PEDAL SWITCH

FIGURE 9 PEDAL CIRCUITS

MODEL A CONSOLES SERIAL NO. 2500 TO 26T6
MOD£L B AND BC CONSOLES SERIAL NO. 5076 TO I0S49
MODEL BA(PLAVEft)C0N50LES-ALL
MODEL C CONSOLES SERIAL NO. liOO TO \247
MODEL D CONSOLES SERIAL NO. I TO 3143
(FOR PEDAL WIRING SEE FIGURE li, COLUMNS i,4,5.e.&.9.10j0

2-21

2N0 PEIWL DRAWBAft

(FOR WFR|^JG SEE fl&JREIi,

■WIBES TO PCD*l. SWITCH

OS 2015

FIGURE \0 PEDAL CIRCUITS

MOOFl a consoles SEPIAL NJO. 2677 TO 27JL
MODEL B, 6C,Ar^D by CONSOi.e& 5£R|Al nO, i05iO TO 17074
MODEL C A»4D CV CONSOLES 5£HiAl_ rXJ. i^-l & ^D \>a7A
WOOEL A(^D DV CONSOLES 5£KIAl «0 H44 TO ^074
WOOEL G CONSOlES-ALL

BE5ii70R P*MEL

^■^0 PEOAL DPA-vaAH

ST P£[W.tmAw BAH

ULTEB I

OS 2016

WlOE^ TO PF2AI, SWITCM

FIGURE 1 1 PEDAL CIRCUHS

MODEL 0V AND CV CDN&OLES $£fil*L NO ITO'S IQ 30^67
MODEL RT CONSOLES SFRiAl Kl. lOOl TO I50<
MODEL ^-2 ANDC-? CONbO^ES ^E«1AL nO 35QOO AND A&OvE
MODEL 6 iANP C-i CONSOLES SEflhAL MO SfeOOO AND ABOUE
fcJlODeL RT-E CONSOLES &EfllAL KtO tSOCJ AND ABOVE
MODEL BT-3 CO»J*iC._E.^ ^ERlAL NO flOOO AND A&OVE
(FOR PEDAL ^VlRlMA SEt F|<iunE 13, COLUMNS I, 7,4,fe, a,a, I0,1l)

FIKST PEDAL DRA

■i^BAR _n

SECOND PEDAL DRAWBAR

ISO OHMS

2
O

82 OHMS

Ifcth HARM,

ta DHMS

IJih HARM

!0'h HARM

3S OHMS

aih HARM

6ih HARM.

flh HARM.

5 b OHMS

Znd HARM-

TO GREAT
MAN. BUS BARS

i-
C

TO PRE-SET PANEL

PEDAL 2

PEDAL

3 f

a::""^

d»|u

-J

3_£

Ird HARM.

10 OHMS

FUND

T"
1

^ FREQ

U NOS.

(-WWV-0 41 J

r-VWW-03£

^WW\— O I

^___ . . J

^ TO INDICATOR
1

4 LIGHTS

^W%A/v-oZ5 H

rvW\^v— ^ tv Q

2-22

WIRING OF PEDAL CIRCUITS
MODEL E CONSOLE

Figure 12

MhIFTES
ON BEAR

SIGNAL
PICKUPS

FOR PEDAL SOLO

PED*L
SWITCH

ACTUATOR

PINS

4 ft ^ ^ «

DOWN STOP
f ELT

FIGURE 21

MODEL RT. RT-2. RT-3 and D-1 00

Pedal Switch Assembly

The pedal switch (shown in Figure 21) is similar in internal construction to the
manuals (Figure 2Z), Each of the 32 pedals actuates a set of contact springs,
making nine contacts available for each note. Each note consists of a funda-
mental and a number of harmonics, no sub-harmonics being used. The pedal
contact springs are connected to terminals by resistance wires similar to those
used in the manual assembly, and a cable connects these terminals to the pro-
per terminals on the generator terminal strip. Only seven contacts are used
for the mechanical generator notes, the other two contacts are used by the ped-
al solo unit as explained later in this book.

Four colored wires carry the pedal tones from the busbars to the pedal draw-
bars. The wires are connected first to a resistor panel on the back of the manual
assembly. A small choke coil and resistor nnounted on the manual assembly are
wired to the lower drawbar (see Figure 23) and serve to filter out any higher
harmonics or transients which might be present in the lower pedal frequencies.

Figure 24 is a wirmg chart for the pedals, showing the frequency numbers appear
ing on each pedal contact.

2-22A

ACTUATOR FOR ONE KEY

TUNING

KEYING

FUNDAMENTAL

2ND, 3RD HARMONIC

2ND HARMONIC

4TH HARMONIC

6TH HARMONIC

8TH HARMONIC

lOTH HARMONIC

fr*

TOP CONTACT SPRING

TOP BUSBAR

BOTTOM CONTACT SPRING
BOTTOM BUSBAR

ARRANGEMENTS OF PEDAL BUSSES D-lOO SERIES

FIGURE 22

2ND PEDAL DRAWBAR

LiJ

1ST PEDAL DRAWBAR

20 0MM5 5 OHMS

z
o

RESISTOR

FILTER I

10 OHMS
AA/WWW-i

WIRES TO PEDAL SWITCH

PEDAL CIRCUITS

FIGURE 23

2-22B

Pedal
No.

Note

Fund

2nd and
3rd Harm.

2nd Harm.

4th Harm.

6th Harm.

8th Harm.

10th Harm.

2 c

29 .

38 ■

50 1

43 ' 55

Frequency

■ Numb

FREQUENCIES USED IN PEDAL SWITCH

FIGURE 24

Pedal Switch Busbar Shifters

The pedal switch'is equipped with busbar shifters similar to those on the man-
uals. The pedal busbar shifter is a slotted stud on the rear surface of the pedal
switch, near the right end as you look in at the back. It should be adjusted as
described under "Manual Busbar Shifters" on a previous page.

2-22C

Pedal Keyboard

Pedal keys are set at the factory for average tension^ but are adjustable to fit
the requirements of the individual organist. Adjustment is accomplished by re-
moval of the top cover at the back of the pedal keyboard and setting the tension
as desired,

PEDAL

SWITCH

PUSHERS

MJium.

TENSION

ADJUSTING

NUTS

PUSHER

ADJUSTING

NUTS

PEDAL
KEYBOARD

PEDAL

COVER

SINGLE
PEDAL

FIGURE 25

2-22D

Ped 'Switch Assembly ■ Model RT, RT-2. RT-3, D-lOO

These models have a 32*note pedal switch assembly, and each note has nine
contact springs which touch nine busbars. Colored wires carry the pedal tones

from the busbars to the resistor panel and drawbars as shown in Figure 11,
(See paragraph on "Wiring of Pedal Switch' in "Pedal Solo Unit' section of
service manual).

Pedal Switch Assembly - Model E

Nine busbars are used in the Model E pedal switch assembly. Figure 12
illustrates the arrangement of these busbars and the nine contact springs of
a typical pedal key. There are 32 pedal keys, and four pedal toe pistons.
These pedal toe pistons, which correspond to the preset pistons of the manuals,
also have nine contact springs touching the same nine busbars and have a
locking arrangement by which only one piston remains in operation at one time.

Frequencies impressed on the busbars, when a pedal is played, are picked
up by the contacts of the pedal piston which is in use, and go from there to
the preset panel through pistons 1 or 2 or to the drawbars through piston 4,
From the coupler (Piston 3) the upper seven harmonics connect to busbars
in the great manual, while the lower two connect to the lower pedal drawbar
and permit it to be used with the coupler. Connections from the pedals to
the manual are indicated in Figure 12, A low voltage line from the pre-
amplifier heater transformer operates the 2.5 volt pedal preset indicator
lamps through the external contacts on the pedal switch. Several filter chokes
and resistors mounted on the pedal switch are wired in series with leads from
the lower pedal harmonics.

Pedal
No.

Note

■a

C rt

-a T3

■

u
a

■

^^
CO

X2
O

r>#

! 16

" 1

32 1

44 1

i 40

' 47

37 ■

38 '

! 44

41 1

44 1

50 1

, 55

Fre

quenc)

' Numb

Pedals 26 to 32 Used In Model £, RT, RT-2, RT'3 & D-1 00 Onfy.
For Harmonics Used In a Given Console See Fig. 8-9-10-11-12,

FREQUENCIES USED IN PEDAL SWITCHES

Figure 13

2-23

Pedal Busbar Shifters

Pedal switches in M consoles (except Model A consoles below serial number
995) are equipped with busbar shifters similar to those on the manuals. The
pedal busbar shifter is a slotted stud on the rear surface of the pedal switch^
near the left end as you look in at the back. It should be adjusted as described
under "Manual Busbar Shifters' on a previous page,

Pedal Keyboard

Pedal keys are set at the factory for average tension^ but are adjustable to
fit the requirements of the individual organist. Adjustment is accomplished
by removal of the top cover at the back of the pedal keyboard and setting the
tension nuts as desired.

SWITCH PUSHER

HINGE SPR

TENSION ADJUSTING NUT

PEDAL KEYBOARD

OS 2043

Figure 14

Preset Panel - Models A, AV, B, BA. BC. BCV, BV, C, CV, D. DV, G,
GV. RT.

The tone signals from the preset keys on both manuals are carried by

color-coded wires to the preset panel in the back of the console.

The preset panel is a set of nine bars* wired to the taps on the matching
transformer, corresponding to different intensities of sound as shown by
numt>ers stamped on the bars. Each preset wire, carrying a single harmonic,
is fastened under a screw on the bar which represents the desired intensity
of that harmonic. This is equivalent to setting a harmonic drawbar to the
corresponding number.

When shipped, each organ has its presets set up as shown in the booklet,
"Creating Beautiful Tone Colors with the Harmonic Drawbars," which maybe
obtained free on request. Preset combinations may be changed at will by
removing the console back and following the directions on a card inside. This
card is reproduced below. (Figure 15)

PresetPanel-ModelsB-2.B-3, 0-2,0-3. RT-2,RT-3,A-1 00, D-IOO&E

In these models the preset panel is divided into two sets of nine bars, each
connected to a separate matching transformer. One set is used for the
swell (upper) manual, and the other for the great (lower) manual and pedals.
The preset panel on Model E is slightly longer than on the other models to
accommodate the two pedal presets.

2-24

Directions for Making Pre-Set Panel Connections

Tlicrc are 9 color-codtd wuc^s ihrraded through one of the lower holes for t-ath pre-set key. Above each hole an.' 9 biiiclinj; posts arranged
in vertival ordt't. and abtjvc tiic uppermost binding post is j name plate ,spceif>in^ the pre-set key associated with the row of wires below.
The lowest hindinir post is that of /ito strength and lorresponds to a }iarmonie

post is of 8 strenplh and corresponds to a hannonic control drawn a
left where they arc marked with their appropriate strength numbers.
For example, suppose the comhinatum 006523411 is to be set up on the D# of the
upper manual It will be foiitid helpful, especially wlien setting several combina-
tions, to use the following chart: —

contnil pnshed all the way in. 'i'he uppermost bmding
the way out. The bus-bar strii^s for each level are extended to the

M.h>ua1 Kiv Brown Red Orange Yellow Green

Blue

Violet

Grey

.Upper 1';^ 6

' 5

III i i

WI-,

Color Code Explanation

Fach group of 9 wires is color-coded as follows;
Sub-fundamental ( brown drawbar) brown wire
Sub-3rd harmonic ( brown drawbar ) red wire
Fundamental
2nd Harmonic
Ird Harmonic
4th Harmonic
5lh Harmonic
6th Harmonic
Sth Harmonic

white drawbar) orange wire
( white drawbar ) yellow wire
(black drawbar
(white drawbar

black drawbcir

black drawbar
(white drawbar

ureen wire
blue wire
violet wire
grey wire
white wire

With a screw driver remove the connections already made on the D# "Upper Manual'^ row of binding posts and separate the 9 wires
from each other, Heferrmg to the chart above, the brown and red wires are twisted together and connected with the bmding post on the
level marked "O" [lowest level). Next, the white and grey wires are twisted toi;cthcr and inserted under the binding post on the level
marked "1," Similarly, the green wire is connected on level ^'2/' the bhjc wire on level "X" the violet wire on level "4," the yellow
wire on level "o," and tlie orange wire on level "6." The wire used for the pre-set connections is standard "push-back" wire. The
.insulation is loose and sliould be pushed back to expose the desired length of bare wire, \cver remove the imuhition hy skinning with
pliers or a knife. After a connection has been made, push the insulation forward with the fingers as far as it will go. Be sure to twist the
wiles together so that tlnre will be no strav strands connecting one bar with any other bar, The binding posts should be firmly tightened
over tlie wires to insure good electrical contacts, PO-2963-1

Figure 15

Matching TraRStormers

The matching transformer is used to match the low Impedance of the generator
and key circuits to the high impedance amplifier input, Tt serves also, through
taps on its primary winding, to establish a series of Intensity levels for the
drawbars and preset panel.

The following types of matching transformers have been used. In most cases
they are not interchangeable, and console serial numbers should be furnished
when ordering replacements.

1. Large-core transformer, used in Models A, B, BA, BC, C, D, and G<
These were enclosed in two sizes of shield cans at various times, but
they are identical otherwise. Two transformers of this type were used
in Model E,

2. Large-core transformer with taps revised. Matching transformers

in organs with non-selective vibrato (Models BV, BCV, CV, DV, and RT)
are slightly different from earlier models in the number of turns to the
first three taps. If a transformer in an earlier organ is replaced by
one of the newer type, any preset wires on preset panel bars 1, 2, and 3
should tje set to the next higher bar in order to make the combination
sound the same as before. For instance, combination 00 3543 HI with
the old type transformer would become 00 4544 222 with the new one,

3. Small-core transformers used in selective vibrato organs Models B'2,
C-2, and RT-2 having preamplifiers code A, B and C. Two transformers
are used in each organ, one with large stack for the upper or swell manual,
one with small stack for the lower or great manual and pedals.

4. Revised small-core transformers with smaller stack and greater number
of turns. These are used in B-2 consoles serial number 42636 and above,
C-2 consoles serial number 42875 and above, and RT-2 consoles serial
number 2381 and above (having preamplifiers code D, E. F, G) and in
B-3, C-3 and RT-3 consoles. Because differences in the preamplifier
input circuits will cause irregular response, these transformers are not
interchangeable with the previous type, unless the preamplifier is changed
at the same time,

5. Model M uses a single small-core transformer without primary taps,
Models M-2 and M-3 have two transformers^ one for each manual, each
transformer identical to the revised lower manual type described in
paragraph 4 above.

OPERATION OF MECH-^NISM ON PRESET KEYS

In their basic construction the preset keys are identical to the playing keys,
Each has a plastic key mounted on a metal channel^ pivoted in the rear and
with a guide toward the front to minimize side motion.

2-25

On the front edge of each channel of the 9 preset keys and 2 adjust k/tys, two
flat springs are attached, one 5/8" long of rather stiff material, and another
approximately 3/4" long of softer material. The softer long spring is sand-
wiched on top of the stiff spring, nearest to the key. The cancel key has only
one heavy spring approximately l" long.

When a preset key is depressed, the longer soft spring is forced downward and
snaps under a tubular rod which is part of the cradle. The cradle is con-
structed of two lubes approximately 6*^ long and assembled 3/4" apart. One tube
is used as a fulcrum, the entire assembly being mounted perpendicular to the
preset keys, A spring and bumper hold the cradle at a 60^ angle toward the front
of the console.

Once a key has been depressed, the soft spring remains under the tube. It is
backed by the short stiff spring to give it sufficient tension to hold the key
down, When the next preset key is depressed, the cradle is forced down and out-
ward, permitting the previously actuated key to come up» but again locking the
one last depressed.

If two preset keys are depressed at Dnce> both will lock down. The cancel key
with its long stiff spring is then used and forces the cradle down, causing all
preset keys depressed to return to their normal position. As there is no lock-
ing spring on the cancel key, it will immediately return to its normal position,

PRESET "cradle'' RETURN SPRING

Earlier instruments had coil springs of various types to perform the function
of returning the cradle assembly to its rest position, and replacement, when
necessary, became rather involved,

A more durable spring has been devised, and is used on the later instruments.
It can also be used for servicing the earlier consoles.

Replacement is made as follows: If it is determined that a new return spring
is necessary, on either manual, the left hand end block of the manual needing
the replacement should be removed. The upper or lower manual assembly will
have to be raised to gain access to the wood screws holding this block. After
removal of this block, the end of the cradle assembly will be visible. Also
visible will be the stop felt and bracket assembly. This is a small angular
bracket with a small piece of felt riveted to it, mounted in a vertical position.
Remove and discard this part.

Install the new assembly so that the felt pad Is above the preset cradle, and
the flat spring is below the cradle, as shown in Figure 16. Clamp it in the
center of the range of adjustment provided by the slot. Check all preset keys

for operation, and adjust the position of the new assembly in case any keys do
not operate correctly.

The new manual preset cradle return spring should be ordered under part number
AO-21709-0.

Figure 16

2-26

TREMULANT SWITCH AND CONTROL
MODELS A-BA-BC-C D -G

The tremulant sometimes called treinolo, is a periodic loudness variation,
or change in intensity, which occurs at a constant frequency. It is funda-
mentally different from the vibrato effect, which is created by a periodic
raising and lowering of pitch.

In the Hammond Organ the trennulant effect is produced and controled
principally by two components: the trennulant switch and the tremulant
control.

The tremulant switch, mounted on the synchronous motor at the extreme
left end of the tone generator, is in effect a variable resistor with no sliding
or rubbing contacts. It consists of an eccentric, geared to the motor shafts
which advances a laminated bakelite strip so as to alternately make and break
6 contacts in order. Five resistors are connected to these contacts^ ranging
in value from 15,000 to 450,000 ohms, together with a length of copper wire
of very little resistance. At one extreme position of the eccentric all
contacts are broken and the circuit is open. At the other extrenne all
contacts are closed and there is practically no resistance in the circuit.

The tremulant control, a 130,000 ohm ^^ariable resistor mounted on the
manual chassis assembly, is in parallel with the trennulant switch. When
this control is turned to a position of no resistance, the tremulant switch is
shorted out. Conversely, when the control is turned to its maximum
resistance, the movement of the eccentric varies the resistance of the
circuit periodically from to 130,000 ohnns. This parallel circuit is in
series with the signal irom the console, ahead of the pre-amplifier . There-
fore, the signal is varied during each revolution of the eccentric by an amount
depending upon the adjustment of the tremulant control.

The tremulant system is not used in console models having vibrato.

Model E

The tremulant system for Model E organ is the same as that on other models
except that two switches are used. Each switch i5 mounted on one of the two
synchronous nnotors that are a part of the nnain generator and chorus generator
respectively, and each one is connected to one manuaL The switch mounted on
the main generator operates at 400 R.P,M, and is connected to the Great nnanual
The other switch operates at 348 R.P.M. and is connected to the Swell manual.

Two types of tremulant switches have been supplied, namely, the cage type and
the enclosed type. These are mechanically interchangeable, but replacing the
cage type with the enclosed type does require a slight change in the circuit.
In the enclosed type, the condenser shown as C5 in Figure 4 is incorporated
within the metal housing. Therefore! the C5 located in the rheostat box is not
required and the tremulant switch red wire may be attached to ternninal 6,7, or
8.

RHEOSTAT BOX

The rheostat box contains the expression control rheostat and other
components, including some terminals associated with the tremulant system.
Figures 1 to 8 show various models of rheostat boxes and their circuits. The
rheostat box is used only in console nnodels with tremulant and with non-
selective vibrato.

The rheostat itself is actually a variable resistor with no sliding contacts.
When the expression pedal is advanced a bakelite csltti moves down, opening
in succession a series of 32 contacts^ tipped with precious metal. The contacts
are connected to fixed carbon resistors.

Resistor RZ in figures 2 and 4 forms a constant load on the matching trans-
former, while R4 and C4 serve to attenuate the higher frequencies. R4 and
C4 were not used in Model A consoles below serial number U3l. The rheoatatj
in series with bass compensating condenser CZ, is across the signal line, so
that when its resistance is least the volume is least. Condenser C5 avoids
excessive tremolo on the lower bass frequencies. It was not originally
installed in Model A consoles below serial number 23U, C3 is a blocking
condenser and R3 is a grid resistor for the first pream^plifier tube.

2-27

MODEL A CONSOLES SERIAL NUMBERED
BELOW ^311 HAVE RED TREMULANT
SWITCH WIRE CONNECTED TO TERM. #7
AND CONDENSER C^ IS OMITTED

-0

HREnSTAT BOX CONNECTIONS
MODEL A CONSOLE

O
O
Z

FIGURE

HEAVY BLACK WIRES
FROM CABLE SHIELDS

.13 MEG. OHM

TREMULANT
CONTROL

■o

,25

-00] MFD

FROM MATCHING TRANSFORMER

-/^a//

AAAa

i^FD 3^^^'^^ ,009MFD JMFD

EXPRESSION PEDAL
> RHEOSTAT

TO
PRE-AMPLIFIER

CIRCUIT OF RHEOSTAT BOX
MODEL A CONSOLE

FIGURE

2-28

n
o

r
o

n
3^

REH TREM

CONTROL
RED TREM

SWITCH

PRE-AMP,
RED

BLACK WIRES FROM
CABLE SHIELDS

RHEOSTAT BOX CONNECTLONS
MODtL B-BA-BC-C-D-C

FIGURE 3

FROM MATCHING TRANSFORMER

-13 MEG. OHM

TREMULANT
CONTROL

-wvx^vw—

vV^r

TREM.

C3
1

^^^ sVircH -oogMFD aMFD

EXPRESSION PEDAL
RHEOSTAT

TO
PRE-AMPLTFIER

CIRCUIT OF RHEOSTAT BOX
MODEL B-BA-BC-C-D^

FIGURE

2-29

MATCH. TRANS.
BLACK

PREAMP. RED CONNECTS TO U, 13 or 15

PREAMP. SHIELD
(pROUND)

EXPRESSION PEDAL
RHEOSTAT

MATCH. TRANS.
SHIELD (GROUND)

RHEOSTAT BOX CONNECTIONS
MODELS AV-BV-BCV-CV-DV-GV-RT CONSOLES

FIGURE

MATCHING
TRANSFORMER

INDUCTANCE
COIL L 36

CONNECTION FOR
INCREASED OUTPUT

PREAMPLIFIER

INPUT

EXPRESSION
RHEOSTAT

CONNECTION FOR
REDUCED OUTPUT

CIRCUIT OF RHEOSTAT BOX
MODELS AV-BV-BCV-CV-DV-GV-RT CONSOLES

FIGURE

2-30

i C. TREM. SWITCH

r. i PPE-AMP.

Ef X BHEO GROUND

P? "^ TftEM, CONTR.

□ 2 MATCH. TRANS.

J21_

GREAT MANUAL
EXPRESSION BHEOSTAT

_lVi_

JTl

Jli.

SWELL MANUAL
t:XPRE5SiON RHEOSTAT

TERM. tl-TREM. SV. ITCH
TERM- I3'PRE-AMP.-RED

;"°LI

MATOH TRANS
TREM. CDNTR.

RHEO. GROUND
PRE-AMP.

TREM SWITCH

r
>

r
c

TERM, #7-TREM. CONTR. -RED
TERM. #9-MATCH. TRANS-Blj^CK
TERM, #10-TREM. CQNTR -BLACK
TERM. *IZ-TREM SWITCh-BLACK

RHEOSTAT BOX CONNECTIONS
MODEL E CONSOLE

FIGURE

SWELL TREM- SalTCH
ON ( CHORUS) GEN

TO PRE-AMPLIFIER

TO PPE-AMPLlFItR

SW ELL

TREMULANT
CONTROL

Ll-J

tjtttAT rflE^.S*ITCH

ON |^^M V^ GEN

INPUT FROM SWELL MANUAL
MATCHING TRANSFORMER

' -5 iNf-UT FROM GREAT MANUAL

MATCHING TRANSFORMER

\ GREAT

I TREMULANT
y CONTROL

ClKGUiT OF BHEOSTAT BOX
|(ODEL E CONSOLE

FIGURE

2-31

THE HAMMOND VIBRATO

THE HAMMOND VTBHATO

Hammond Organ consoles equipped with vibrato diifer from tremulant models
in the omission of the tremulant switch, tremulant control, and non-vibrato
preamplifier, and in the addition of the vibrato line box, scanner, vibrato switch,
and vibrato preamplifier. Three degrees of vibrato are available and also a
different decree of chorus or celeste effect with each of the three degrees of
vibrato. Console models with the suffix "2" and "3" in their model designation
have the selective vibrato feature, with tilting control tablets permitting the
player to place the vibrato effect on either manual or both.

PRINCIPLE OF OPERATION

The vibrato effect is created by a periodic raising and lowering of pitch, and
thus is fundamentally different from a tremolo, or loudness variation. It is
comparable to the effect produced when a violinist moves his finger back and
forth on a string while playing, varying the frequency while maintaining constant
volume.

SIGNAL FHOfc t

riRST SECTION

Of PREAMPLIFIER

AMPLIFIER

SECTIONS OF VIBRATO LINE

Signal '0 SECOND

AMPLiFIE*! I seCTjOH OF PREAMPLIFIER'

Fig, 1 - FUNDAMENTAL DIAGRAM OF VIBRATO EQUIPMENT.

2-32

The Hammond Organ vibrato equipment (see simpiLfied block diagram, Fig. 1

varies the frequency of all tones by continuously shifting their phase. It includes

a phase shift network or electrical time delay line, composed of a number of low
pass filler sections, and a capacity type pickup or scanner, which is motor driven
so that it scans back and forth along the line.

Electrical waves fed into the line are shifted in phase by each line section (the
amount per section being proportional to frequency), so that at any tap on the
line the phase is retarded relative to the previous tap.

The scanning pick-up traveling along the line will thus encounter waves in-
creasingly retarded in phase at each successive lap^ and the signal it picks up
will continuously change in phase. The rate at which this phase shift occurs will
depend on how many line sections are scanned each second.

Since a cycle is equivalent to 360 electrical degrees, a frequency shift of one
cycle occurs for each 360 electrical degrees scanned per second. For example
if the scanner passes over the line at such a rate that 3600 electrical degrees
are scanned each second, there will be a frequency change of 10 cycles.

For the widest vibrato, the whole line is scanned from beginning to end in about
1/14 second, and this rate of change of phase causes about 1-1/2^ decrease in
frequency. Note that the frequency remains constantly 1-1/2% low as long as
the moving pick-up retards the phase at a constant rate.

Since the pick-up sweeps from start to end of the line and then back, it in-
creases the frequency by an equal percentage on its return trip, the average
output frequency remaining equal to the input frequency. The exact amount
of frequency shift depends not only on the amount of phase shift in the line but
also on the scanning rate. This rate, however, is constant because the scanner
is driven by the synchronous running motor of the organ.

The degree of vibrato (or amount of frequency shift) may be varied by a
switch (not shown in Fig. 1) which causes the whole line to be scanned for
#3 (wide) vibrato, about half of it for #2, and about one third for #1.

A vibrato chorus effect^ similar to the effect of two or three slightly out-of-
tune frequencies mixed together, is obtained when the vibrato output signal
is mijced with a portion of signal without vibrato. For vibrato chorus, part of
the incoming signal appears across the vibrato line and the rest across a
resistor in series with the line. As the vibrato effect is applied to the part
of the signal appearing across the line but not to the part appearing across the
resistor, the combination produces a chorus effect. For normal vibrato, this
resistor is short-circuited.

In ^selective vibrato consoles the vibrato effect can be applied to either
manual separately or to both at once.

CONSTRUCTION OF COMPONENTS

Figures 2 and 3 show different models of the vibrato line box. Each of the
air core inductance coils is connected with one or more condensers to form
one filter section.

Figure 4 shows the construction of a typical vibrato switch. Some models
diflfer in wiring and number of contacts, but all are similar in mechanical
arrangement.

The scanner (fig. 5) is mounted on the main generator synchronous motor and
driven at 412 revolutions per minute. It is a muLti-pole variable condenser
with 16 sets of stationary plates and a rotor whose plates mesh with the
stationary ones. In figure 5B two sets of plates have been removed to show
the rotor.

Signals coming from the line through the vibrato switch appear on the stationary
plates and are picked up, one at a time, by the rotor. Connection to the rotor is
made by carbon brushes as shown in figure 5A. Two brushes touch the sides of
the contact pin and a third presses on the end, in order to eliminate the possibility
of contact failure.

' ..Htt "f^P ■hD HtXiiUhL XLJUtlftt

r\o.2

vjbrato li*^e box

FIG 3

ViWato line box

Uiio WITH tincuiT i^owm ih f icvre »

SCHEMATIC DIAGRAMS

Figures 6, 7, 8 and 9 show four different vibrato circuits which have been used
in various models. As the components of different types are generally not
interchangeable, it is important that model and serial number be furnished when
ordering replacement parts-

Non-Selective Vibrato

Figure 6^ used in all consoles with V in the model designation, has a 25 section

vibrato line. It is wired (to minimize the number of compensated take-off points)

so that the last part of the line is used for #1 vibrato. The vibrato switch has

positions for three degrees of vibrato (VI, V2 and V3) with three ''off'' positions

between them, and there is a separate vibrato chorus switch. A resistor connected

to the "off" side of the chorus switch serves to maintain constant volume tor the

two switch positions. The switch is not intended to be left in its middle position.

The preamplifier used with this circuit is actually two separate cascaded
amplifiers on one chassis, with the vibrato system connected between them.
The first section drives the vibrato line, and the second section amplifies
the signal picked up by the scanner. The "vibrato off" contact in the vibrato
switch carries non-vibrato signal directly to the second section of the
preamplifier. The complete schematic circuit of a console of this type is
shown in Figure 7 of section 2, and preamplifier in Figure 6 of section 11.

2-33

'o F f'oR *C H RU S*CO N TACT

CABLE ,

TO LfN£ /

^T"

^^^^^^^^^iV^^^h^^kV K W ■ I ^^B^^''fl^^r ^^^^QB^^Hj^iitB^^^^^Hfl^^^^^^^^^^^

cable'

to scanner

MOVING CONT^TS COjr^ECT
rO 3CAMNER

fig,4 vibrato switch

(bottom view with cover removed)

•

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FIC. » SCANNER

Selective Vibxato

Figure 7, used in early selective vibrato consoles, also has a 25 section line.
To obtain correct phasing of the 'vibrato" and "no vibrato" channels, the first
part of the liie is used for #1 vibrato. The vibrato switch has no "off"
position, and three vibrato chorus positions (CI, C2 and C3) are included in
it as well as the three vibrato positions (VI, V2 and V3). The vibrato effect is
turned on and off for each manual separately by means of "vibrato swell" and
"vibrato great" tablets on the manual assembly.

The preamplifier used with this circuit, as indicated in Figure 9 of section 2,
has two separate channels into which signals from the "vibrato great" and
"vibrato swell" tablets are fed. The "vibrato" signal goes through a pre-
liminary amplifier, through the vibrato system, and then into additional stages
of amplification. The "no vibrato" signal also has a preliminary amplifier,
but by-passes the vibrato system and goes directly into the foUowing amplifier
stages. The preamplifier alone is shown in Figures 20 and 20A of section U.

Line with Resistor Dividers

The vibrato line box of Figure 8 employs resistors for voltage dividers at the
compensated pick-off points instead of condensers. Otherwise this circuit is
identical with that of Figure 7. The line boxes of these two types are inter-
changeable, and the scanners and switches are identical.

Coupled Line^

Figure 9 shows the coupled-coil type of vibrato line box. It is smaller In size
and requires only 18 sections to give the same amount of vibrato effect as the
25 sections previously used. The switch has one less contact in each position,
and so neither the vibrato line nor the vibrato switch is interchangeable with
earlier types. The preamplifiers are the same as those used with the circuits
of Figures 7 and 8. The scanner has somewhat different wiring harness.

MODEL "m" vibrato SYSTEM

2-34

The vibrato system in the Spinet Model M Series is somewhat different from
those described above. The line box is slightly smaller, the scanner is slightly
different mechanically, and a completely different switching mechanism is used.
A full description is given in the service books for these models.

O0T*^uT OF

OUTPUT 0^

FiGURE 6-VlBRATo S^STEf/l

_itO i»* All WODtL AVh tt, tCVfc tV* Diih A»^0 HT" C014^0lE_^

VIBRATO PM*iE iHlFT Ht^E

FiGuHE 7 - VfcBHATO ^Y^TErvl

W&ML C 1 CDP4^0lE^ tELQ* i£Wi*L NuMfct^ MTZJ

2-35

OUTPUT Of

£KW*7

ViBBATO PH^^ ^HlFT UNE

FiGURt 3 -VIBRATO SYSTEh^

UDQtL B-Z CONiOLt^ SERIAL, Ha^MR iTjofl TO ^^^OO^ KH^ ^€,\0\ T0-*fri5-4

MOMI. 02 CONSOLES btRiA.L hUbA^tR Ji?za TO ^tStJ

I Put u^

#4 PD^I^OiH^^^ APd CZ

MFOa-TbOPv^ VL MA Ck

ViVtA-TO 1-1 Wt

^ 1 ^1
^ ^ ^ S ^ ^ ^ ^

ViBflAtO PHftSF Shift LIhjE

FI6URL SV^BRATO SVSTEM

MDOtLC-l CC+4UC£.S ^£RlAL_ H^JMfrtR AW»4Z ^si^ 4&0^^

M(xlelA-100
Model D-100

2-36

THE HAMMOND ORGAN WITH PERCUSSION.

Percussion tones are available only on the upper manual (with the B adjust key
depressed) of all consoles with the suffix "3 in their model designation. These
consoles, except for the four percussion control tablets in the upper right hand
corner, look and function similar to consoles with the suffix *2 in their model
designation, when the percussion effect is not in use,

1. THEORY OF OPERATION

The percussion tones are produced by borrowing the 2nd or^ 3rd harmonic signal
from the corresponding drawbar (of the upper manual ''B adjust key' drawbar
group), amplifying it, returning part of it to same. drawbar, and conducting the
balance through push-pull control tubes, which when keyed cause the signal to
fade away at a pre -deter mined rate.

2, GENERAL CIRCUIT OPERATION (All Reference Is To Figure 24 Section 2)

With percussion tablet "on", upper manual "B adjust key" and an upper manual
playing key pressed, the 2nd or 3rd harmonic signal appearing on an upper
manual busbar is conducted through "B adjust key' drawbar wire to input of
percussion amplifier (terminal H) and amplified by T4 and V5, Besides provid-
ing push-pull signal for the control tube V7, the percussion input transformer
T5 has a third winding which feeds the signal back to the 2nd or 3rd harmonic
drawbar through equivalent key circuit resistor R50 and terminal J. Thus the
signal that was borrowed from the 2nd or 3rd harmonic drawbar for the per-
cussion amplifier is replaced.

When a key is depressed the signal first sounds loudly through the control tube,
transformer T6, a high pass filter, and terminal D to the grid of V4, Immediate-
ly condenser C31 in the control tube grid circuit begins to discharge, causing the
signal to fade away. Terminal K (approximately +25 volts) is connected to the
8th harmonic "B adjust key" drawbar wire which is connected to manual busbar.
When an upper manual key is pressed, terminal K is grounded through the tone
generator filters. This virtually grounds the plate of V6 (connected as a diode),

stops conduction, and isolates cathode and control tube grid circuit. The grid
then drifts from approximately +25 volts to about +15 voltSj at a rate determined
by the time required for C31 to discharge through R57 and R58. At the com-
pletion of this sequence the percussion signal is blocked. No further percussion
effects occur until all keys of the upper manual are released and control grids
can again rise to ^25 volts. The rate of this rise is fixed by the time required to
charge C31 to +25 volts through R55 and R56,

3. FOUR PERCUSSION CONTROL TABLETS. CUTOFF CONTROL, AND THEIR
FUNCTIONS,

The Percussion On-Off Tablet when turned "on" does five things to the signals of
the upper manual "B adjust key" drawbars,

(a) It disconnects the 2nd harmonic drawbar from its signal wire,

(b) It disconnects the 3rd harmonic drawbar from its signal wire.

(c) It connects the 2nd or 3rd harmonic drawbar signal wire (depending on
position of Harmonic Selector Tablet) to input of percussion amplifier.

(d) It disconnects the 8th harmonic drawbar from its signal wire. This wire
(connected through generator filters to ground when any key is pressed) is con-
nected to terminal K. The 8th harmonic signal is not available on the upper

2-37

manual as long as percussion tablet is "on",

(e) It inserts resistor Rl in series with upper manual matching transformer
(T2) secondary to reduce upper manual organ signal so that lower manual will
musically balance with the combined upper manual organ and percussion signals.

The Preset Percussion Switch is not part of the control tablet assembly or per-
cussion on-off tablet^ but functions as an interlock with it. It is located under the
upper manual "B adjust key"'. This switch insures that the full upper manual sig-
nal is restored by shorting out series resistor Rl introduced by the percussion
'on" tablet when any other upper manual preset or adjust key is pressed.

The Volume Tablet in ''soft" position shunts resistor R46 across the percussion
output transformer, reducing percussion signal, and also shorts out upper manual
matching transformer compensating resistor Rl thus restoring upper manual sig-
nal strength to provide proper balance between the manuals.

The Decay Tablet in ''fast" position shunts resistor R57 across the slow decay
resistor (R58) reducing time for decay capacitor C31 to discharge and for V7
control grids to reach cut-off. Also to preserve the same effective loudness in
"fast decay" position as in "slow decay the control tube bias is reduced by dis-
connecting R59 and allowing control tube grids to become more positive which
increases output signal about 50%.

The Harmonic Selector Tablet does three things to the signals of the upper man-

ual *'B adjust key" drawbar group:

In ''Second^ Position:

(a) It connects the 2nd harmonic signal wire to percussion amplifier input.

(b) It connects the 3rd harmonic signal wire to the 3rd harmonic drawbar,

In ''Third" Position:

(a) It connects the 3rd harmonic signal wire to the percussion amplifier input.

(b) It connects the 2nd harmonic signal to the 2nd harmonic drawbar.

The Percussion Cut-off Control which is located on the amplifier should be re-
adjusted as follows whenever control tube V7 is replaced:

Set expression pedal wide open, both volume tablets "normal ,
percussion "^on , percussion decay "fast", and harmonic selector
in either position. Depress any key in upper half of upper man-
ual and then adjust cut-off control exactly to the point where
signal becomes inaudible.

2-38

REVERBERATION CONTROL

Reverberation control la an important feature of any Hammond Organ installation.
This device is enjoying wide acceptance because it produces reverberation in var-
iable degrees so the Hammond Organ, when installed in an acoustically "dead"
enclosure, sounds very much like an organ played in a large acoustically "live"
church or auditorium where organ music, enhanced by considerable reverberation
sounds at its beat.

Reverberation is the prolongation of sound by repeated reflections or echoes,
and Is measured by the time required for a sound to become inaudible after
the source of sound has been stopped. It is present in sonie degrees in all
enclosures, and music is more pleasing to the ear when accompanied by some
amount of reverberation. This is particularly true of organ music. ,

Reverberation results from the fact that the longer path traveled by reflected
sound causes a delay in hearing the reflected sound waves. This is easily
realized in the case of sharp staccato sounds and a fairly distant reflecting
surface, as the delayed sound is then heard separately frorn the direct sound
and LS recognized as an echo. When music is played In a large room, howeverj
the sound echoes and re-echoes repeatedly until absorbed by the surroundings.

The Hammond reverberation control is an electro -rnechanical device which
introduces multiple echoes by means of reflections within a network of coil
springs and thereby provides adequate reverberation in locations where the
natural reverberation is not sufficient.

OPERATION OF FLUID TYPE

The fluid type reverberation unit (see figure I), about 4x3 inches in cross section
and about 4 feet high, is connected to a reverberation preamplifier built into the
power amplifier. (In some inodels of tone cabinets the reverberation preamplifier
is a separate unit connected to the power amplifier by cables. ) The entire equip-
ment is attached to the organ tone cabinet.

Reverberation is applied to the organ inusic after it leaves the console. Part of
the console signal goes directly to the power amplifier and part goes into the
reverberation channel, after suitable amplification.

The electrical signal fed into the reverberation unit is converted into mechanical
energy by a moving coil driver unit, similar to a dynamic speaker without a cone.
The mechanical waves are transmitted through coil springs, which have the
property of conducting sound vibrations much more slowly then the speed of sound
waves in air. In this way a spring of convenient length can introduce a delay
equivalent to that obtained in a large hall.

The driver unit, at the top of figure Z, introduces up-and-down vibrations into
the stirrup directly under it. The two enclosed springs under the stirrup hold
it in position but permit it to n:iove freely up and down, and the spring at the far
left balances the pull of the others. These three springs are almost entirely
imniersed in dannping fluid, as they act largely as dampers to stabilize the re-
sponse of the driver and prevent underaired reflections.

A sound wave from the stirrup travels down the open spring at the far right to
the crystal pickup, where an electrical signal is produced and conducted to the
power amplifier. This is the "first reflected signal"', delayed about 1/15 second
from the part of the original signal which went directly to the power amplifier.

The same wave from the stirrup also travels down the second spring from the
le£tj which enters the short damping tube , At the bottom of this spring the
wave is reflected back along the spring, reduced in intensity by the damping
action of the fluid. At the stirrup the horisontal lever transfers the wave to
the right-hand spring, and it goes on to the crystal to produce a "second re-
flected signal'* about 3/15 second after the direct signal-
Very little of the energy of each wave is absorbed by the crystal, and the rest
is reflected back along the spring. The "first reflected signal ' traverses the
right spring, is transferred by the lever, and goes down the spring to the short
dannping tube .

Here it is reflected in reduced intensity, retraces the same path to the crystal,
and produces a "third reflected signal' about 5/15 second after the direct signal.
The "second reflected signal" is similarly repeated, and this process continues
over and over, giving a series of signals about 2/15 second apart, until the
vibration is dissipated by fluid friction in the short tube -

Just above the short damping tube a "reflecting pin" attached to the spring
causes partial reflection of high frequencies and helps to make the over-all
response more uniform.

The damper felt avoids undesirable transverse vibratioih o£ the springs.

A greater amount of fluid in the short tube will cause increased energy loss at
' each reflection and thereby reduce the number of audible reflections. Adjusting
the level of fluid in this tube, therefore, changes the reverberation time and
simulates enclosures of different sizes.

2-39

UPPER LEVER

DRIVING UNIT
VOICE COIL

STIRRUP

LOWER LEVER

CAWPER FELT
1-^- LOCK PLATE

SPRING E

REFLECTI^JG PIN

LOCK PLATE

° LOCKINGLEVER

CONNECTOR RrBSON

TO AMPLIFIER

REVERBERATION UNIT
FIG. 2.

FIG. 1

A "reverberation selector awitch" in the amplifier circuit following the
crystal can be adjusted to pass more or less of the reflected signal in pro-
portion to the direct signal. While thia does not actually change the rever-
beration time, it is a convenient way to change the annount of reverberation
instantly. Generally, therefore, the fluid level in the short tube is left con-
stant, at the position recommended on the tone cabinet instruction card, and
the switch is used to select the best amount of reverberation for each
installation.

The photograph of the reverberation unit (Figure 1) shows a reverberation pre
amplifier of the type used in kits for installation in some non -reverberation
lone cabinets. In later reverberation type tone cabinets the power amplifier
is wired so that this preamplifier is unnecessary.

Amplifier circuits associated with the reverberation unit are shown in The
section containing amplifier diagrams,

INSTALLATION OF FLUID TYPE

2-40

In installations of tone cabmets using type F, type G, and type H power ampli-
fiers, only a single reverberation unit is necessary for any installation, regard-
less of the nunnber of tone cabinets used. The reverberation unit is connected to
the first power arnplifier (the one to which the console cable connects) and the
reverberated signal is supplied from that amplifier to additional cabinets*

An exception occurs in the case of type HR-40, KR-40 and JR-20 tone cabinets,
in which no reverberated signal la available for additional cabinets (because of
the separate bass and treble channels). If reverberation is desired on several
H, J, or K series cabinets, each must be equipped with a reverberation unit.

When two or more types of cabinets are used in any installation, it is preier-
able that anv H or K series cabinets be connected to the console ahead of any
cabinets having type F, type G, or type H amplifiers in order that reverber-
ated signals may not enter the bass amplifier channel. Otherwise there may be
objectionable irregularities in the response of the lower pedal notes.

Further information on the use of reverberation may be found in the section
covering Acoustics.

FILLING AND ADJUSTMENT OF FLUID LEVEL

When installing a reverberation unit or tone cabinet, the damping fluid (fur-
nished in bottles with the unit) should be added with care, following directions
on the tone cabinet instruction card- The level in the three long tubes is not
critical; for best damping it should be near the top, but not high enough to spill
if the unit is moved. Enough fluid is furnished to fill each tube to about one
inch from the top.

The short tube should be filled to exactly 3-1/4 inches from the top, using
the special suction bulb supplied. This amount of fluid gives the best rever-
beration effect for average conditions.

If acoustic conditions are very unusual, or if an organist has a defintte pref-
erence for greater or less reverberation, the level in the short lube may be
set higher or lower. Lower fluid level will give longer reverberation time
and higher fluid level will give shorter time. There is a temperature effect
due to change in viscosity of the fluid (lower temperatures will shorten the
reverberation time and higher temperatures will lengthen it) but no adjust-
ment for this effect is necessary unless the temperature is consistently
below 50^ F or above 95^^ F.

The reverberation selector switches are set at "HT' when leaving the
factory, and should be readjusted on installation to give the most desirable
reverberation effect. If th^re is any uncertainty as to the proper adjust-
ment, it is generally preferable to allow too much reverberation rather
than too little .

OPERATIONAL ADJUSTMENTS OF FLUID TYPE

It is a well known acoustical phenomenon that audibility of some frequencies
is emphasized over others in any given enclosure. Range of frequencies af-
fected depends upon the size and type of reflecting surfaces such as walls
and ceilings. Thus if a musical instrument such as an organ is played in an
enclosure of almost any size, some frequencies will sound louder in one

portion of the listener area than in another, and conversely some frequencies
will sound weak. This can be effectively demonstrated by playing the organ
in a em.all room with a microphone, then listening to the signal picked up by
the microphone in another room. Variations in loudness will be startling
especially when single frequencies are sounded.

The reverberation unit similarly produces a "response pattern" which tends
to emphasize some frequencies over others to a slight degree. This is an
operating phenomenon of the equipn^ent and cannot be eliminated. This room
pattern effect has not proved seriously objectionable ^ because as described
above it stimulates an acoustical effect which is present in some degree
whenever any musical instrument producing a wide range of frequencies ia
played in an enclosure.

If some notes on the organ sound excessively loud while others sound weak
it may be traceable to the reverberation control system. In investigating
this, disconnect the reverberation system by turning the switch on the re-
verberation preamplifier or amplifier to the "off" position. If notes then
sound at equal loudnes s , turn reverberation system on again and make the
following adjustments:

I. The two-pole plug, which is connected to wire carrying signal
to the driving unit at the top of the reverberation unit, niay be
inserted in two positions. Reversing this plug by turning it at 90^
will reverse the input signal phase, thus changing the response
pattern of the reverberation system. Reversing this plug will
often improve evenness of overall frequency response for a
given installation.

Z. Sometimes evenness of frequency response can be improved by
cutting down amplitude of the reverberated signal. This is ac-
complished by changing the position of the reverberation switch.
If switch is on "HI" move it to "Med", and if switch is on "Med"
move It to "Lo. "

Exact recommendation on adjustment of this switch is somewhat difficult
as the purpose of the reverberation control is to compensate for lack of
natural reverberation. Adjustment of it therefore should be made in co-
operation with the organist, who m.ust understand its intent. In large in-
stallations the use of two reverberation units will reduce roorn pattern
to the point where it is negligible.

2-41

MOVING THE FLUID TYPE UNIT

The reverberation unit appears to be a delicate device but when once set up
it L6 very dependable and requires no further attention. When a tone cabinet
la moved even a few feet, however, the reverberation unit must be locked
to avoid excessive vibration of the springs. If the cabinet is to be tilted, the
unit must be removed, to avoid spilling the fluid, and replaced after moving.
If the unit itself cannot be kept upright while moving, the fluid rnuet be
drained and later replaced. Hammond damping fluid is a grade especially
selected for this purpose, and no other kind shouid be used.

Failure to lock the unit when moving usually necessitates replacement of
Jhe complete driver assembly or the upper or lower lever assemblies
which are a part of it- When parts are replaced, the springs must be balan-
ced as follows:

In a connplete driver assembly ordered for replacement, the
wire passing through the unit from the upper lever to the stirrup
is not soldered. It should be left unsoldered until this adjust-
ment is made. Replace the driver assembly and attach all the
springs; check and adjust the single damping tube, U necessary,
to make the upper lever assembly level. Then solder the wire
to the small tube passing through the voice coil. When only the
upper or lower lever assembly is replaced, the wire need not
be unsoldered, but the upper level must be made level by ad-
justing the single tube.

Reproduction of caution tag attached to

reverberation unit

OPERATION OF DRY TYPE

A later reverberation device, Figure 3, is an improved unit which enriploys
a dry damping means instead of the liquid previously used. It has improved
driver and pickup elements and has three transmission springs instead of the
one formerly used.

The device is about fourteen inches high, thirteen inches wide and two inches
in depth- It is incorporated in the new PR-20, PR-40 and QR-40 lone
cabinets. It is also supplied as part of a kit which is designed for installation
in Spinet and Chord Organs.

In operation, an electrical signal from an amplifier is applied to the driver
unit in the reverberation device which then converts the electrical signal
into mechanical energy which is fed into the three springs of different
lengths. The signal takes 1/22 second to traverse the shortest spring

to the pickup, which reconverts part of the energy to an electrical signal
and reflects most of the energy back along the spring to the driver, where
again most of the signal is reflected back along the spring to the pickup.
This transaction continues until the signal energy at the pickup is reduced
to one millionth of its original value. This period is about two seconds in
duration. The other two springs operate in a similar fashion, but their
reflections occur at longer time intervals, 1/17 and 1/15 second res-
pectively. The amount of damping for each of the three springs is so pro-
portioned that they have a uniform decay rate.

2-42

OPERATION IN PR AND QR SERIES TONE CABINETS

The dry type reverberation device mounted in the PR and QR series tone
cabinet functions as follows. Part of the console signal is applied to the re-
verberation driver and the resultant reverberated signal at the pickup is
separated into two frequency bands, one occupying the spectrum from thirty-
two to two hundred cycles, and the other from two hundred cycles to six
thousand cycles. The low frequency reverberated signals are mixed with
the direct console signals, amplified and fed to the low frequency speakers.
The high frequency or treble reverberated signals are amplified and fed to
a separate speaker system, while the treble signals from the console are
also amplified and fed into another speaker system. In other words, the low
frequency direct and reverberated signals are electrically mixed and the
high frequency direct and reverberated signals are acoustically mixed.

Two selector switches are mounted on the side of the PR and QR series
tone cabinets to provide a variation in the amount of reverberation produced.
The base reverberation switch provides increased direct output as the
amount of reverberated signal is reduced. This is accomplished by introducing
more or less direct signal into the bass channel as the amount of reverbera-
tion is decreased or inci:eased. The treble reverberation switch controls the
gam of the treble reverberation amplifier channel, but if the switch is
turned to the "Reverberation Off" position, the direct console treble signal
IB fed mto this channel to provide full treble acoustic output from the cabinets.

LEVELING TABS

PICK UP"

W?IVER

TWISTED PAIR
'DRIVER" INPUT

SHIELDED LEAD
PICK UP" OUTPUT

SPRING "-3

LIM^T CHANNEL

*' » I*

-I

LIMJT CHANNEL
CLIP

2-43

INSTALLATION OF PR AKD QR TONE CABINETS

Vvhen these tone cabinets are installed the "Room Size" control on the rear of
the amplifier chassis should be adjusted in accordance with the instruction
card in the tone cabinet, and the reverberation device should be unlocked.

Warning: Whenever the cabinet is moved, even one or two feet, the rever-
beration device should be locked. Failure to do this may cause one or more
springs to become unhooked from the driver or pickup assembly.

Tone cabinets embodying this reverberation unit do not provide a rever-
berated signal to other tone cabinets. If more than one tone cabinet of the
type normally embodying this unit is used and reverberation is desired from
all tone cabinets, then a reverberation unit must be included in each tone
cabinet-
Kits are available which will permit turning the reverberation on and off
from the console without the use of additional cables. Several different
kits are available . depending upon the type of console , and the instruction
sheet accompanying each kit describes the installation and operation. These
kits are designed for use with PR and QR series cabinets only.

SERVICE SUGGESTIONS

Should no reverberation be evident in playing a tone cabinet equipped with
this device, but a loud noise results from touching the aprings. it is quite
likely that the lockmg device has not been completely opened. Make sure that
the springs of the unit are free of the clamps, which are located near the
driver and pickup.

If in moving a tone cabinet a spring is disengaged from the driver or pickup,
the ends can again be reinserted in the loops. For proper operation it is sug-
gested that the reverberation unit be removed for this operation and the loose
springs be allowed to hang quietly, then the end should be picked up and in-
serted in the loop from which it became disengaged. The purpose of this
procedure is to eliminate any twist within the spring which could cause er-
ratic noises in operation because of torque which would be transferred to
the pickup portion.

REVERBERATION IN EARLIER TONE CABINETS

On previous models of tone cabinets which are installed without reverberation
units and there is now a desire to add such a refinement, it is necessary that
the fluid type kits be purchased. For the applicable kit. consult our D-2 Price
List showing these kits. Because of mechanical and electrical considerations
the later dry type can not easily be included in earlier model tone cabinets.

REVERBERATION IN SELF' CONTAINED UNITS

Self contained models of the Hammond Organ (A-100. M-lOO, L-lOO) contain
a somewhat similar reverberation unit, except the reverberation springs are
taunt and self contained. The size of this unit is approximately 17" long
4-1/Z" high and i-l/Z" wide.

Reproduction is quite similar to the necklace unit, This unit does not require
any locking or unlocking in m.ovement.

All repairs and adjustments on this item must be made at the factory and no
repair parts are available.

2-44

EQUIPMENT FOR THE HAMMQWn

An echo tone cabinet (or group of cabinets) may be used with any type of
tommond Organ console. The echo cabinet is usually placed at some distance
from the console and from the main cabinet: for instance, at the opposite end
of a church. An echo switch mounted on the console enables the organist to play
through the main cabinet alone, the echo cabinet alone^ or both together. Any
standard Hammond tone cabinet may be used.

The echo switch has three positions. When it is set to the left the main
tone cabinet (or cabinets) will sound, and when set to the right the echo cabinet
will sound. With the switch in the center both main and echo will sound simul-
taneously. The switch controls only the signal circuits, and all cabinets remain
energized as long as the console Is turned on.

Figures 1 and 2 show how the main and echo tone cabinets are connected
to the console, and figure 3 is a schematic circuit of the echo system.

ECHO ORGAN KIT

The Echo kit includes all necessary parts for installation in consoles Models
B, BC, BCV, BV, C, CV, D. DV, G, RT, B-2, B-3, C-2, C-3, RT-2 and RT-3, with
the exception of some early B and BC consoles having no outlet box. For installing
kit in a console without an outlet box, or in Model A or Model E console, see spe-
cial instructions at the end of this section.

A 5-conductor cable must be ordered separately, of suitable length to reach
from the console to the echo cabinet, in addltilon to the desired echo cabinet (or
cabinets).

.AC Li>tf.CQKQ

*C POWER ■'o c*Pi»*T5^s »*cn

PPEAVPLlFlLD

ECHO

SWITCH

CD»-WLt

C*BI'><f

ECHD TONE
t^filh-El

TO ElTHECl i*Bl**T
OB TO BCt

FIGURE I BLOCK DIAGRAM OF ECHO ORGAN

ion b-

CONDUCTOR
CABLE

AC LINE

COPi^

CABLE

a 'POL

PLUG

T
£ AC

tPOLE
'echo CA&^tl'
REilEPTAtLE
\H CQhJMuE

■«*IN CABlMEl"
HECePlMLt
FN COhSXE

FIGURE 2 CONNECTIONS OF CONSOLE
TO MAIN AND ECHO TONE CASlNETS

INSTRUCTIONS FOR INSTALLING KiT

1, Disconnect chorus drawbar (if console has chorus generator) from
lever inside console by removing coupling pin. Detach vibrato chorus switch
(if any) by removing knurled nut from front. Remove four screws in music
rack end biccks and remove entire music rack assernbly from console,

2. Drill holes for echo switch in music rack bA&e as shown in figure
4, Replace music rack and other parts. Mount echo switch.

2-45

Note: St*.ps 3 and 4 apply only to consoic models having "B"^ in the tvpe
designation. * ^^^

3. Disconnect and remove swell pedal connecting rod. It console has
chorus generator, it will be necessary to unfasten nr*-^rY,^Hn ^^J'^'^"^ ^^^

{leaving wires connected) and remove ^mounting channef"^'^'"^ '"' ^'^°^^^ ^'^

4. Remove 4 screws from pedal switch cover panel, remove key at
top of wiring tube nearest to swell pedal, raise lube a few inches, and lift
pedal switch cover panel.

Note: Step 5 applies only to console models having C, D, G, or R in the
type designation.

5. Remove key at top of wiring tube and raise tube a few inches to
permit detaching the outlet box.

6. Unfasten outlet box from base of console, open it, knock out pro-
per receptacle hole blank (see figure 5) and mount echo receptacle. Solder
connections as indicated in figure 5. Pull twisted pair of wires up through
wiring tube. Reassemble outlet box and atUch it to console. Replace pedal
switch cover if it was raised in step 4»

Note: For consoles not equipped with outlet box. see special instructions
at end of this section.

7. Replace any other parts previously removed. Fasten echo wiring
panel on top of line panel cover and connect all wires as shown in figure 5.

8. Check for proper operation. If it should happen that the echo cabi-
net sounds with the switch in "main" position and the nnain cabinet sounds
with the switch in "echo" position, interchange the main and echo cable wires
at the echo wiring panel,

INSTALLING KIT IN MODEL E CONSOLES

In this model the preamplifier is located so far from the line panel
that the blue, green, and black wires from the echo panel must be extended
to reach the preamplifier- In addition, the black and red cable wires must
be extended to reach the echo panel. Otherwise the installation may be made
as described above.

ECttD

MAIN

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hJAiN

BtAtK

RED

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UAJN

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111

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1200

*200

ECHO

GHD,

eLH:f^

R£D

FRDU tCKO
PECEPTACLi
\H OUTLET aOv

TO PREiMPLiTIER

FIGURE 3 - SCHEMATIC DIAGRAM OF ECHO KIT WIRING

2-46

*Note: On consoles with start and run switches in wood end block {B-3,
C-3 and RT-3) increase this dimension to 3 17/32"

RI5HT END OF
MUSIC HAC» Base

-41(066; DRILL
2- HOLES
CTSh to V32" Dri

FIGURE 4-HOLES TO BE PROVIDED FOR MOUMTllMG

ECHO SWITCH

INSTALLING KIT IN EARLY MODEL B AND BC CONSOLES WITH NO
OUTLET BOX

When installing an echo kit in one of these consoles, it is preferable that
an outlet box be installed at the same time.

(a) Order from the service department of Hammond Organ Co. "one out-
let box with 6-conductor receptacle, 2 conductor plug and mounting
screws; one 6-conductor plug, and one plug cap," stating the model
and serial number of the console.

(b) Follow steps 1, 2, 3 and 4 above.

(c) Mount echo receptacle in outlet box (see figure 5). Cut off 6-cond-
ductor cable to proper length to connect it to outlet box, and mount
6-conductor plug and plug cap on remaining piece of cable. Figure
6 shows connections to plug and receptacle.

(d) Follow remaining part of step 6 and follow steps 7 and 8.

Figure 7 shows position in which outlet box should be mounted
on console.

INSTALLING KIT IN MODEL A CONSOLES

In this model the installation of the echo switch is complicated by the fact

that the right hand wooden end block is very thick and has no flat front surface to

accommodate the switch plate. Contact the service department of Hammond Organ

Co. for further information. ElectricaUy the installation is the same as for the
other models.

2-47

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2-48

MONAURAL EARPHONE CONNECTIONS

Earphones can be added to the console for practice purposes so as not to disturb
others. Earphones at best cannot replace the tonal quality achieved frona the
instruments' own speakers but do make the organ "more available".

One method of attaching earphones is shown in the sketch below, using a
reluctance type headset of good quality. Inserting the phone plugs silences
the speakers m the console. Wiring is between the preamplifier terminals
marked "G " and the main amplifier mput.

G •■

SWITCHCRAFT
SF-JAX -^25 OR 55

GND

C 9-

I 500 ^ , W

^VAW^.

5Ci. -^ . W

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TO AMP

STEREO EARPHONE CONNECTIONS

A second method of attaching earphones is given below. This will provide a
stereo effect that is well worth the cost and effort expended. Koss or Jensen 4
ohm stereo phones are recomnnended.

Turn over AO-39 chassis and disconnect two black wires from the BN-BK
speaker terminal inside of the amplifier. Leave output transformer lead
connected. Connect the two wires removed, to the center lug of the three
lug terminal strip nearest the front of the chassis and solder connections.

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2-49

2. Replace amplifier and place a solder lug under the mounting screw nearest
the output transformer,

3. Remove the brown wire from the BN-BK speaker terminal on the AO-39
and solder it to the lug just installed.

4. Remove the green wire from the GN speaker ternriinal on the AO-39 ampli-
fier and splice on an additional length of wire long enough to reach the ear-
phone jack and switch which will be mounted on the front of the console.

5. Solder a wire to the GN speaker terminal on the AO-39 long enough to reach
the earphone jack.

6. Solder a wire to the BN-BK speaker ternninal on the AO-39 long enough to
reach the earphone jack.

7. Identify the green and black wires on the center speaker that connect to
the AO-35 or AO-44 amplifier. Remove these wires and connect the green
wire to the GN speaker terminal and the black wire to the BN-BK speaker
terminal on the AO-39 amplifier.

8. Identify the speaker terminals on the reverberation amplifier AO-35 or
AO-44, If a black wire is soldered to the left speaker terminal on the
amplifier, reverse the speaker leads at the amplifier so that the gray wire
is on the left lug and the black wire is on the right lug of the annplifier
speaker terminals.

9- Remove the blue wire that is connected to the speaker directly above the
reverberation amplifier. Splice on an additional length of wire long
enough to reach the earphone jack,

10. Solder a wire to the empty lug on the speaker long enough to reach the ear-
phone jack,

11. Solder a wire to the right speaker terminal long enough to reach the ear-
phone jack. (This terminal is grounded inside the AO-35 or AO-44 chassis.)

12. Mount all components to the right of the dotted line shown on the diagram
in a suitable box and connect as shown. Numbers shown under wires
identify these leads based on the preceeding steps,

13. Mount box containing switch and earphone jack at a convenient point at the
front of the console.

PHONO INPUT

A microphone or record player pickup nnay be used through the organ if desired
The preamplifier is equipped with a standard phonograph input jack. The input
impedance is approximately 1 megohm and the circuit requires a nnaximum in-
put signal of about 1/2 volt. A volume control will have to be installed between
the microphone or record player input and the organ inasmuch as the swell
control of the organ does not affect this input.

2-50

SECTION III

LIST OF ILLUSTRATIONS ANO INDEX

PAGE

LIST OF ILLUSTAATION AND INDEX 3-1

Mode}* A, B. BC, D. fliG 3-2

Wmng Diaoram (Figure 15) 3-2

Schamst^c (Figure 16) ..,3-3

Model A'1 00 3-59

Schamatic (Figure 30| 3-59

Wirma Diagram [Figuri 31) 3-60

Modal BV, CV 34

Wiring Diagram (Figufa 17) 3-4

Schematic [Ffgufe 18) 3-5

Modal C'2G 3-6

Wfhng DiBflram 3-6

Schematic 3-7

Models 82 & C2 3 8

Wiring Diagram fFiQure 20) 3-8

Wiring Diagram (Ffgura ZOA) 3-9

Sehemitic(FlBura21) 3-10

Models B-3 & C-3 3-11

Wiring Diagram {Figure 23} 3-11

Schematic [Figufa 24) 3-12

Modal D'lOD 3-66

Schemaiic|FigurB33) 3-6B

Wiring Diagram (Figure 35) 3-67

ModfllE 3 18

Wiring Diagram (Sheel 1) 3-18

Wiring Diagfam (Sheei 2) 3-19

Modal RT 3-13

Wiring Diagram (figure 19) 3-13

Schematic IBV^BCiRT) (Figure IB)

SEE PAGE 3-5

Model RT-2 3-14

Wiring Diagram (Figure 22) 3-14

Wiring Diagram (Figure 32A) 3-14

Schematic (6-2. C-2. & RT-2)

SEE PAGE (Figure 21 3-10

Model RT'3 3-16

Winng Diagram (Figure 25A) 3-16

Schematic (B-3, 0-3, Bi RT-3)

SEE PAGE (Figure 24) 3-12

raUkl SOLO UNIT

General 3-21

Wirtng Oiagfams 3-22

Tumny 3-23

Block Diagrams (Figure 1 & 1 6) 3-24

Model RT Schematic 3-25

Model RT-2 Schematic 3-26

Tuba Vottages 3-28

Service Suggeitiont 3-29

Removing Pant 3-30

Parts Ust 3-31

Winng Diagrami Pedal Solo Generator 3 31

(Figure 4. 4B, d 4C) 3-32

MmJFICATIQN SYSTEM

Pra-AiTipJifiar Schematics

Modat A (Figure 1 1 3-35

Models A & B {Ffgure 2 A 3) 3-36

ModeksA,B, C, U, PiByar& G

(Figure 4 & 5) 3-37

Models AV. BV, BCV, CV. DV & RT

(Figure 6) 3-38

Model E (Figure 7) 3^38

Model E (Figure 8 & 9) 3-39

POWER AHPLIFIER SCHEMATICS PAGE

(USED INTONE CABINETS)

Models A-2a A-40, B-40. C-40 (Figure 10) 3-40

Models A-20. A-40. B^O, C-4D, 0-20.

DR-20. G, DX-20 (Figure 11} 3-40

Models D-20. DR-20. B-40, ER-2a

Fft'20. F-40 (Figure 12) 3-41

ModeliD-20,F-4O.FR40 (Figure 13) 3-41

Models DR-2D,ER'20.FR-40 (Figure 14) 3-42

ModBliH-40,HR-4O (Figure 15) 3-42

Models H-40. Hfl-40 (Figure 16) 3-43

flEVERB PREAMPLIFIERS SCHEMATICS

Models DR-20. ER-20 (Figure 17) 3-44

Models OH-20. £R-20. FR-4D (Figure 1 8| 3-45

POWER AMPLIFIEft SCHEMATIC
(USED IN TONE CABINETS)

MODELS H-40. Hft40 (Figure 19) 3-46

Mudels H-4D. HR-AO (Figure 1 9B) 3-*7

PRE-AHPLIFIER SCHEMATICS

Models B-2, C-2. RT-2 (Figure 20| 3-47

Models B-2, D-2, RT-2 (Figure 20A) 3-47

POWER AMPLIFIERS SCHEMATICS
(USED IN TONE CABINHS)

Modal JH-20 (Figure 22) 3-48

Model JR-20 (Figure 22A) 3-49

Model JR'20 (Figure 22B| 3-49

PREAMPLIFIERS SCHEMATICS

Models B-3, C-3, RT-3 (Figure 24) 3-50

POWER AMPLIFIERS SCHEMATICS

(USED IN TONE CABINETS)

Models PR-40, Ofl-40 (Figure 26) 3-50

Models PR-2D (Figure 28) 3-51

TONE CABINETS

Models PR-40, OR-40 3-52

Models PR-40^ DR-40 (Figure 26A|

Schemetic 3-53

Models PR-4Q. QR-40 (Figure 27A)

Schematic leler units 3-64

Models P-4D, a-40 3-55

Models P-4D, Q-40 (Figure 29)

Schematic 3-56

Model PR-20 3-57

Model PR 2D Schematic 3-58

POWER AMPLIFIERS

(USED IN CONSOLES)

MODEL A-1 00 3-61

Schematic (Figure 32) 3-61

Wiring Diagram (Figure 33) 3-62

Model 0-100 (Figure 36) 3-68

REVERBERATION AMPLIFIERS
(USED IN CONSOLES)

Model A-100 (Figure 34) 3-63

lFigure35) 3-64

(Figure 35A) 3-65

TROUBLE LOCATION 3-69

Trouble Shoottng 3-69

Soctione^izing Trouble 3-75

Troutiia Shooting Chert 3-80

Repair & Disassembly of Vibrato Scanner 3-82

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3-20

PEDAL SOLO UNITS

CONCERT MODEL CONSOLES

The Model RT Hammond Organ console is similar electrically to the Model CV
console, but differs In the following respects:

L The console woodwork is larger and somewhat different in design.

2. The pedal keyboard is concave, with 32 pedal keys.

3. The pedat solo unit is added to provide deep and rich pedal tones
desired by the concert organist.

The Model RT-2 console includes the above features and also has the selective vibrato

system as used in Model C'2,

The Model RT-3 Console is similar to Model RT-2 with the addition of the percussion

feature.

The Model D-l 00 Console is similar lo Model RT-3 with the addition of a built-in power ampli-
fier and speakers,

PEDAL SOLO UNIT

The pedal solo unit incorporated in these consoles provides a series of briffht pedal
solo tones in addition to the usual pedal accompaniment tones available on other
models. The pedal solo tones, generated by a vacuum tube oscillator circuit, are
controlled by a volume control knob and eight tilting slop tablets, of which one turns
all the pedal solo tones on or off and the others provide various pitch registers and
tone colors. The pedal solo unit is independent of the electromagnetic tone wheel
generator and can be turned off without affecting the remainder of the organ.

Only one pedal solo note will play at a time (if two pedals are depressed at a time,
only the higher one plays) but this does not affect the foundation or accompaniment
tone controlled by the two pedal drawbars. It is possible, therefore, for the left foot
to play a bass accompaniment note set up on the pedal drawbars, while at the same
time the right foot plays a pedal solo note (the accompaniment tone on this higher
note being masked by the high solo quality).

The pedal solo unit is designed as a part of these consoles, and because of mechan-
ical limitations it is not adaptable to any other model.

NOTE: Pedal solo generators of all types have slightly different electrical
circuits but are interchangeable in all RT series consoles. Type RTA was used in
all Model HT and some Model RT-2 consoles. Types RTB and RTC were originally
used only in Model RT-2. Types RTD and PTE have improved components - but no
change in circuits.

HOW THE PEDAL SOLO UNIT WORKS

All notes of the pedal solo unit are controlled by a two-triode vacuum tube master
oscillator circuit operating at audio frequencies from 523 to 3136 cycles per sec-
ond, corresponding to 1 fool pitch. Thus the master oscillator operates over the
full pedal keyboard range of 32 notes. Each time a pedal is depressed, its tuning
contact tunes the oscillator to the pitch associated with *he corresponding key in this
32 note range.

The output of the oscillator is fed into a series of five cascaded frequency dividers,
each of which divides its input frequency by two and thus produces a note an octave
lower than its input frequency. The five dividers thereby provide pitches of one.
two, three, four, and five octaves below the pitch of the oscillator. In this way, when
the oscillator is tuned to some given note, each divider produces a note in exact
octave relation to the oscillator, thus forming a series of sijt notes having exact
octave relationships. The particular frequency divider or dividers selected for
sounding through the amplifier and speaker system of the organ will depend upon
which of the stop tablets are used,

A control contact under each pedal causes the control tube to transmit the signal to
the amplification system with a controlled rate of attack.

COMPONENTS OF THE PEDAL SOLO UNIT

Electrically the pedal solo unit is very similar in principle to the Hammond Solovox,
Model L, although there are, of course, many differences- It employes tuning coils,
tuning adjustment knobs, a master oscillator, and frequency dividers similar to
those in the Solovox. and the stop tablets are similar in function to the register con-
trols of the Solovox.

The pedal solo generator is a chassis which looks like an amplifier and contains the
master oscillator, five frequency dividers, an amplifier, a control tube, and a power
supply. It is located directly above the pedal switch assembly, near the left side of
the console as viewed at the rear.

The tuning coil assembly contains 32 adjustable inductance colls, which tune the
master oscillator to the frequencies of the 32 pedal notes. It is mounted above the
pedal switch assembly, near the right side of the console as viewed at the rear.

The control panel, with eight stop tablets and a volume control knob, is mounted at
the right end of the lower manual.

The pedal switch has nine contacts under each pedal key. One is used for tuning the
pedal solo unit, the second serves to key the amplifier and make the pedal solo note
sound, and the other seven carry harmonics from the main (tone wheel) generator lo
the pedal drawbars as in the B and C series consoles-

3-21

WIRING DIAGRAMS

In studying the operation of the pedal solo unit, refer first to the block diagram
(figure 1) and second to the more detailed schematic circuit (figure 2, 2B or 2C}.
The schematic diagram of the console, apart from the pedal solo unit, is the same as
for the Model CV, C-2, or C-3 console, shown in section 2, Actual connections be-
tween the pedal solo unit and other parts of the console are shown in the wiring
diagram in section 2.

The Oscillator

The 32 coils which lune the audio frequency oscillator are shown in figure 2. When
the lowest ^^C" note is played (this pedal has no tuning contact ), all 32 coils are
connected in series to form the tuning inductance of the oscillator. When any other
pedal is depressed, its tuning contact shorts out some of these coils (making less
total inductance) and thus tunes the oscillator to the higher pitch associated with that
note. If two pedals are depressed at the same time only the higher pitched of the two
will sound.

Frequency Dividers

Each divider includes three triodes. One acts as a driver and pulse rectifier, supply-
ing sharp and narrow negative pulses to actuate a symmetrical feed-back tripping
circuit comprising two triodes. Either one (but only one) of these two triodes can be
conducting at a time, for by drawing plate current it holds the other in a cut-off
condition.

Suppose, for example, that the first triode is conducting and the second is cut off.
Now a negative input pulse impressed on the grids of both triodes will not affect the
second one, which is already cut off, but will cut off the first. This produces a
positive pulse at the plate of the first triode, which is applied to the grid of the second

triode through its feedback connection. The second triode then suddenly conducts
current, producing a negative pulse at its plate. This negative pulse, applied to
the first triode grid through its feed-back connection^ insures that the first triode
remains cut off. The situation is now exactly reversed, with the first triode cut off
and the second conducting.

The next input pulse will act on the second triode, cutting it off again and making the
first conductive; and thus two input cycles are required to produce one out-put cycle.
Each frequency divider circuit therefore divides its input frequency in half, produc-
ing an output signal one octave lower than the preceding divider. One triode plate of
each divider stage furnishes a signal of rectangular wave shape to the following
driver tube, and output signals are taken from the driver and divider plates as in-
dicated in figures 2, 2-8 and 2C.

This divider circuit is capable of operating satisfactorily with wide variations in
voltage, input frequency, and values of components, and therefore is remarkably
stable and requires no adjustments.

Stop Tablets

From the preceding, we see that whenever any one of the three G pedals, for instance,
is depressed, the frequency dividers, together with the oscillator, provide a series of
six G notes in exact octave relations. The particular divider whose output is to sound
is selected by the stop tablets: 2' & l', 4\ S\ 16\ 32' BOMBARDE and 32' BOUFtDON.
Thus the stop tablets act as register controls to shift the pitch range of the pedal solo
unit to five different positions. If two or more of these controls are turned on simul-
taneously, a composite tone wjU be heard, consisting of the output of several divid-
ers simultaneously sounding in their octave relations. (A tablet is "on when the
white dot is visible.)

Note With Regard To The 32-£oQt Stops

In playing, care must be exercised by the organist in using the 32' BOURDON and 32'
BOMBARDE pedal stops. They are useful in permitting the player to obtain deep
bass notes in the second octave of pedals. As the player descends into the first octave
of pedals, he will find that the B, A#, A, and G# pedals have a definite pitch like the
higher pedals. However, below the G# pedal, it becomes difficult to ascribe a defin-
ite pitch to these 32-foot tones. When a 32-foot stop is registered in concert organ
music, it will be found that the pedals required will rarely be lower than the G pedal
in the first octave. Therefore, do not use the 32-foot pedal stops indiscrim inately

for ordinary bass purposes where the 16-foot ton e is desired. The 32 BOURDON
stop produces an effect which is mostly "felt"^ as a very low bass undulation when
playing low in the first octave of pedals. The 32' BOMBARDE is always used in con-
junction with other higher pitched stops. When played by itself in the lower half of
the lowest octave of^pedals^ the effect is of such low pitch as to be of little use
musically.

'MUTE*

Pressing the mute tablet shunts a small condenser across the signal circuit to reduce
the intensity of the higher frequencies. This is effective on all the pedal solo slops to
make the tones more mellow.

'PEDAL SOLO on' '

This tablet, connected in series with the keying contacts in the pedal switch, turns on
and off any solo combination set up on the other tablets. It may thus be used as a
preset control for the pedal solo unit.

3-22

Volume Control

The volume knob on the control panel is used to balance the pedal solo tones with the
rest of the organ. The over-all volume of the entire organ, including the pedal solo
unit, is controlled by the expression pedal.

Control Tube

The push-pull control tube, a double triode. is normally cut of f by a large negative
bias applied to its grid circuit. When any pedal is pressed its control contact grounds
this bias circuit (if the "PEDAL SOLO ON tablet is "on"), thereby removing the bias
and causing the note to sound. A condenser and resistor, C81 and R112, make the tonal
attack smooth. The control tube is connected to an output transformer whose second-
ary feeds the pedal solo signal through the volume control to the organ preset panel,
where it is combined with the other tones of the organ.

Tuning

All notes of the pedal solo unit are simultaneously tuned by adjusting two tuning knobs
located on the pedal solo generator. These change the frequency of the master oscilla-
tor by shunting small additional capacitors across the main tuning condenser.

To tune the pedal solo unit to the organ, proceed as follows:

(a) Press only the "4"*, "MUTE', and ^PEDAL SOLO ON" tablets and hold down the
middle D# pedal. The pedal drawbars must be pushed in, and the vibrato should
be off,

(b) Pull out only the first white drawbar for either manual and press the correspond-
ing preset key. Hold down the D# key above the middle C» with the drawbar and
the volume control knob set to give approximately equal volume.

(c) Set the "fine tuning' knob on the pedal solo generator to its center position and
adjust the "rough tuning' knob to the point which brings the two notes most near-
ly in tune (slowest beat between them). Then adjust the "fine tuning knob to make
the beat as slow as possible. While it is generally not possible to tune exactly to
zero beat, the accuracy of tuning provided will be found to be sufficient.

(d) The organist may prefer to have the pedal solo generator tuned slightly sharp to
increase the "chorus effect' between it and the main tone generator. To tune it
sharp, lurn the "fine tuning" switch counterclockwise one step.

Ijotei Never tune on the lower pitch registers (especially the 32-foot range) where
the pitch acuity of the ear is insufficient for accurate tuning. If the 4-foot stop is
tuned as directed above, all other registers will be in tune because they are locked
by the frequency dividers to exact octave intervals.

Wiring of Pedal Switch

The nine contacts of each pedal key make contact with nine busbars extending the
length of the pedal switch assembly. One set of contacts and the corresponding busbar,
used for tuning the pedal solo unit, are wired to a terminal panel on top of the pedal
switch, where the tuning coil cable connects. The other eight sets of contacts are
wired to the main tone generator as indicated in the pedal wiring chart in the section
on manuals and pedals, although only seven sets are actually used to carry tones from
the main generator to the pedal drawbars.

The contacts of one set (the one marked ''12th harmonic in the wiring chart) are used
as control contacts for keying the pedal solo unit. The fact that they are connected
to ground through the pedal switch wiring and the tone generator wiring does not

affect their use for this purpose, since the keying circuit Impedance Is high by com-
parison. The busbar for these contacts is wired to a terminal on top of the pedal
switch to which the white keying wire from the pedal solo control panel connects.
These contacts are wired to the main tone generator in the usual way in order that
they mdy supply the I2th harmonic in case special circumstances make it desirable
to omit the pedal solo unit. In this case a green wire from the pedal resistor panel
on the manual assembly (It will be found wrapped around the pedal switch cable) is
connected to the busbar terminal on top of the pedal switch (see wiring diagram in
section 2). The pedal tones will then be identical to those on the B and C series organs.

3-23

TONt

TONE

UPPER

Playing kCvS

ADJUST HtTS

PRESET KETL

Dff Aip^JBAR5

LOWER

MA>JyAL

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PEDAL
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■CONTROL
TUBE

VOL^AilE

CONTROL

CONTROL CIRCUIT lo VAKf. PED*L NOTE SOUhiD

POWER
AMPUIfl(P

LCM)
iPEAKERS

REvEngERATION
U*JiT
(OPTHXAtJ

10NE CAfilNET

FKL I - Block diagram of hammond organ

MODEL A.B,BC.BCV,BV,CXV,D,OV.G.flT

COhsolE

PERCySSlOh
MODELS B-3

C-a,RTi OMl^T

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FIGURE IB' BLOCK OfAGRAM OF ORGAN MODEL B 2.B3,C 2.C-3.RTa. OR RT-3 W^TH SELECTIVE VIBRATO SYSTEM

(B AMD C hCCCL5 CO HO* KiiVE PEOAl ^U3 UHIT)

3-24

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3-27

TUBE SOCKET VOLTAGES
For Pedal Generator Stamped "Type RTA*

For voltages of other models see correspondinfr ^schematic diagrams,

Thei^e readings are taken with a lOOO-ohms-per-voll meter having three scales of
50, 250 and 1000 volts. All voltages are taken with 117 volt line, and deviations of as
much as 20 per cent may be caused by line voltage variations- The "PEDAL SOLO
on" tablet must be "on'\ and other tablets may be either on or off- No pedal should
be depressed unless specified. The negative lead of the voltmeter is connected to
ground except as noted. See figure 5 for terminal locations.
Connect Positive Meter should read Meter
Voltmeter lead to: (volts) Scale This shows voltage of:

'^290"

^270"

"M20"
■» 20"
Ground (neg. to "-37 )

Tube VI (term. #3)
Tube VI (term- #B)
Tube V2 (term. #2)
Tube V2 (term. #3}

Tube V2 [term. #5)

Tube V2 (term, #6)
Tube V3 (term. #2)

Tube V3 (term. #5), V6 (term-
#3). V8 (term- #2 & #5)

Tube V4, V5, V7, V9, VIO
(term. #2 and #5)

Tube V12 (term. #3)

Tube V12 (term. #8)

Tube V13 (term. #2 and #5)

290

1000

270

1000

120

250

190

:ooo

B.5

230

1000

5.5

180

1000

250

Connect Positive
voltmeter Lead to:

Same, any pedal pressed

Tube V13 (term. #3)
Same, any pedal pressed

Tube Vll (term. #8)

1st Filter Capacitor
2nd Filter Capacitor
3rd Filter Capacitor
Divider Bias
Control Tube Bias Supply

Master Oscillator Plate

(1st section)

Master Oscillator Cathode

(1st section)

Master Oscillator Plate

(2nd section)

Master Oscillator Cathode

(2nd section)

Oscillator Rectifier Plate

Oscillator Rectifier Cathode

Driver Plate

250 Driver Plates

55 to 75

250

Divider Plates

120

250

Preamplifier Plate

Preamplifier Cathode

120

250

Control Tube Plates

Meter Should

Meter

This shows

Read (volts)

Scale

Voltaee of;

105

250

Control Tube Plates

Control Tube Cathode

290

1000

Rectifier Cathode

AC VOLTAGES
Heater voltage to all tubes except Vll
Rectifier tube Vll heater voltage
VH term. #4 or #6 to "-37"

6 V. RMS

5 V. RMS
280 V. RMS

AC ripple across 1200 ohm resistors R99. RlOO, RIOl

(connect a 1/4 mfd. condenser in series with meter) Less than 2 V. RMS

AC ripple across 5000 ohm resistor R105 (connect a

1/4 mfd. condenser in series with meter) Less than 1 V. RMS

3-28

PRACTICAL SERVICE SUGGESTIONS

The foUowing suggestions cover possible Iroubles in the pedal solo \init only. SuggeS'
tions for the standard organ system will be found elsewhere in the service manual

Any trouble in the organ ahead of the matching transformer will not affect the pedal
solo unit, but trouble following the transformer will affect both systems equally.

Pedal solo unit does not play. First make sure that the tubes are lighted, all con-
Irols are in playing position, and the rest of the organ plays normally. Several
possible causes of trouble are listed below in order of probability,

(a) Tubes. The tubes are all standard radio types and can be tested in the usual
way. Figure 3 shows their locations in the pedal solo generator.

(b) Loose cable connector. See that the ISPole plug and the shielded plug are
inserted tighUy into the pedal solo generator.

(c) Keying circuit. A dirty contact in the "PEDAL SOLO ON' tablet or a defective
connection in any part of the keying circuit will prevent removal of the cut-off
bias when a key is played. If this is the trouble, grounding pin 15 of the cable
plug will make a pedal note sound. The following section, "Procedure for
Removing Parts", tells how to reach and clean the tablet contacts.

(d) Amplifier or oscillator circuit. The amplifier circuit is conventional in most
respects, and voUas^e measurements will generally serve to identify any
trouble. Failure of the master oscillator will make the pedal solo unit fail to
play, and voltage readings will be helpful in this case also. Figures 4, 4A, 4B
show the locations of all components, and a chart at the end of this section gives
their characteristics.

TOP VIEW Of CHA5 5I5

HE! TIFIEB DU"VFF*^ D.JiOER i^iwiDEI*

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FiGunt a- Peda; ^oin GFMKftAiOR

Pedal solo note does not sound on one pedal (with any combination of control
tablets). The control contact of that pedal is probably dirty and can be cleared by
adjusting the pedal busbar shifter as described in the section on manuals and
pedals. The same trouble may appear as an irregular sputtering or crackling of a
single pedal note.

This effect may also result from an open circuit in the pedal wiring, the pedal-to-
main-generator cable, or the main generator wiring, since the control circuit is
completed through the main generator.

A ll pedals jail to play on one stop tablet . If all other tablets play correctly, the
signal from the oscillator or one frequency divider is not reaching the amplifier.
This may be due to a loose cable plug, a broken wire, or a dirty contact on the
tablet. In the latter case, refer to the following section, "Procedure for Removing
Parts'", The schematic diagram, figure 2, indicates which cable wire and fre-
quency divider correspond to each tablet. Figure 5 identifies the tablets and
electrical components in the control panel.

All pedals play the wronR pitch (or do not play at all) on one or more low pitched
stop tablets. One frequency divider is not operating correctly, in which case all
dividers below it will also fail. A cathode-ray oscilloscope connected from ground
to the plate of any divider tube should show a rectangular wave, while the plate
of any divider driver tube should show a very sharp and narrow negative

pttlse. If electrolytic capacitor C78 is open or very low in capacity, all the dividers
may fail to operate.

3-29

Key thumps or clicks . If capacitor C 81 is open, there will be a loud thump each
time a pedal 15 played.

Hum. An excessive 120 cycle hum in the output will result from failure of one of the
filter capacitors C75, C76, C77 and C78

Tuning of individual notes. The individual note tuning system consists of 32 small

inductance coils, each of which is adjustable by moving the coil on its iron core.
This tuning system is very stable because it has practically no aging effect and is
very insensitive to ordinary humidity and temperature changes. However, after long
use under adverse climatic conditions it is possible that some pedal solo notes may
not be exactly in tune with each olher.

Always tune first with the tuning knobs as indicated above. Keep in mind the fact
that it is generally desirable to have the pedal solo unit slightly out-of-tune with the
organ. If you are sure some notes actually require tuning, proceed as follows:

(a) Disconnect the two cable leads from the G-G terminals on the preamplifier and
ground the two wires. Connect one set of oscilloscope plates (either horizontal
or vertical) to one G terminal and ground.

(b) Connect the other set of oscilloscope plates to ground and to pin 3 of V6 through
a blocking condenser.

(c) Remove the cover of the tuning coil box at the rear of the console, exposing the
numbered tuning coils. The wiring diagram shows the location of these coils.
Set the fine and rough tuning knobs to their center positions.

(d) Push in the pedal drawbars, turn the vibrato off. and turn all pedal solo tablets
off. Using only the first white drawbar on either manual, hold down the second key
G key from the top. Hold down the highest pedal,

(e) Loosen the clamping screw on coil 32 and slide the coil carefully forward or back-
ward until the note is in tune as indicated by the oscilloscope wave pattern stand-
ing still or moving no more than one cycle in two seconds. Tighten the clamping
screw.

(f) Release key and pedal and press adjacent F # key and pedal. Adjust coil 31 in
same way. Repeat for all other pedals and coils in chromatic order downward.

It is important to start with the highest pedal and progress downward one pedal at
a time because the tuning of the lower notes is dependent upon all of the higher
coils. Each pedal adds an increment of inductance in series with all coils above
it^ and adjusting any single note will detune all those below it.
Note: From the above you can see that tuning the individual notes is a long and tedious
process and must be done with extreme care. It should not be undertaken unless you
are absolutely certain that the tuning error is great enough to interfere seriously with
playing the organ,

PROCEDURE FOR REMOVING PARTS

To remove Control Panel ajid Clean Contacts

1. Remove four screws holding music rack and place it on top of console.

2. Remove two hex head manual bolts exposed when music rack is removed,

3. Remove two large hex head manual bolts located on underside of generator
shelf near rear,

4. Remove two screws passing up through right-hand chassis block of lower
manual into control panel,

5. Remove one screw holding angle bracket to bottom cover of control panel.

6. Tilt upper manual upward and slide control panel assembly through opening
toward back of console,

7. Remove bottom cover of control panel.

8. Remove four wood screws holding wood frame work to chassis of control paneL

9. Remove knob and loosen nut which holds volume control.

10. Tip wood frame up and slide back until rear wooden strip clears tablet identifi-
cation strip,
n. Slide pivot rod out of tablet assembly and remove tablets,

12, Remove four #3 screws holding tablet assembly to chassis of control panel, and
tilt assembly up. Contacts are now visible and can be cleaned by wiping gently
with a cloth.

3-30

ELECTPICAL PARTS LIST FOR PEDAL SOLO GENERATOR

CONDENSERS

REFERENCE SYMBOL

CAPACITY VOLTAGE TYPE

C75

20 mid.

400 Electrolytic

C76

20 mfd.

300 '

C77

80 mfd.

150

> Elet

:trolytic

C78

30 mfd.

Used in Generator

C79

30 mfd.

"Type

RTa" or

iiy

C76

40 mfd-

Tn' Elec ,

^Irolvtic

AO-19131-1

C77

20 mfd.

^^^ '•> Not Used in Generator

C78

20 mfd.

350 1 -Type

RTA'^

C79

6 mfd,
WIRE WOUND

200 J
RESISTORS

REFERENCE SYMBOL

OHMS

WATTS

PART NUMBER

R 1051 Used in Generator

(5000

R lD6/"Type RTA" only

4^00

626-060741

VARIABLE RESISTOR

REFERENCE SYMBOL

OHMS

R 118

250

TRANSFORMERS

REFERENCE SYMBOL

FUNCTION

PART NUMBER

T 1

Power

:i5V. 60 cy.

T 1

Power

IISV. 50/60 cy.

T 1

Powe r

230V, 50/60 cy.

003-021320-003

T 2

Audio

T 3

Output

r~^r ] ;5) @

4- -oH

rCLLOHM

c 50

GHCT
ViOlE

BlUC

T( rCl-LOw

nUiHl ''-UNDEPSIDE OF PtDAL SOLO CtlKERXTOft TYPE RTA

3-31

F1&URL4B-LJNDERSJDE OF PtOAL ^LO GENERATOR TVPE RTB

O II

o) o

EAHLV JNLT^ Of= ThF.sE 1 VPfS HAD

a c H£D_

La J

BtFtRENLt ^TF,l&Ol.i rOR roMpOHtuT^ F^CFER TO PtD*L SOLO
FIGUHt4C -UNOtR^lOE. QF PEOAL ^LO OENERaTOR T*Pf. PTC AND A&QtfE

3-32

PEDAL SOlO on

itQ

SS'BCJRDON 32'&0N^BAR0E MUTE

QiEMi

ItO

MD^

WHITE TC PLDAL

Switch op -us

WHITE ^15 OR

PEDAL SWITCH

T3 BLUE

»9 ORtU
BLU

rK^;-

• I3V\0LET

c^/;

*146REY T2 GREEN*

• 7 GREEN

*2 RED

r- • I BROWN

T3_
RED

O-

♦ 3 ORANGE

BLACK

♦ B YELLOW

¥D

a-'

.-RsrV'

V^ irrr^

:^^
O

le'

2^t'

GREY

VIEW OF
CABLE SIDE

OF Plug

WHITE

ACK TO
05 5AR

EEN TO
BUS BAR

-3:a3

VIOLET

WHUE TO
PEDAL SWITCH

REFERENCE SYMBOLS FOR COMPONENTS REFER TO PEDA. SQLO

UNIT SCHEMATIC, FIGURE 2

FIGURE 'UNDER5JDE OF PEDAL 5OL0 CONTROL PANJEL

3-33

3-34

AMPLIFICATION

THE AMPLIFICATION SYSTEM

The electrical impulses which produce the tones of the Hammond Organ are
given their original amplification by a preamplifier located in the console, and
are then transmitted to the power amplifiers which are located in the tone cabi-
nets. It will be noted that no power transformer is included in the preamplifiers
shown in figures 1 throiigh 9, the required plate current being supplied by the
power amplifier In the first tone cabinet . Later models of preamplifiers have
a complete power supply incorporated within them.

A tone control is included in all preamplifiers whereby the relative intensity
of the high and low frequencies may be changed to suit acoustical conditions by
varying the amplitude of the higher frequencies. On tremulant equipped consoles
this control will be found under a screw cap located toward the right end of the
chassis, while on consoles equipped with the Hammond Vibrato this tone control
will be found under the cap marked "HI IMP INPUT/ Selective vibrato consoles
have the tone control located midway on the preamplifier chassis.

A microphone or phonograph pickup may be used with the organ if special
circumstances make it desirable. On tremulant type consoles the input terminal,
marked "p'' on the preamplifier, goes through a screen by-pass condenser to the
screen of the input t\ibe. This terminal is normally grounded, and the input
device should have an impedance of 500 ohms or less in order not to reduce the
volume of the organ, A signal level of a volt or more is required to drive this
point, and therefore it is suggested that the microphone or phonograph be
connected through a suitable preamplifier having an output impedance of about
200 ohms.

On vibrato consoles the Input terminal, located under the cap marked "HI IMP

input" on the preamplifier, goes to the grid of one input tutie. This circuit has
an input of 1 megohm impedance and requires an input signal of about 60 millivolts
maximum-
Most preamplifiers used on selective vibrato type consoles are equipped with a
standard phonograph input jack. The input Impedance Is approximately 1 megohm
and the circuit requires a maximum input signal of about 1/2 volt>

The push-pull signal line from the preamplifier output transformer to the tone
cabinets has a total impedance of approximately 200 ohms. As it is connected
directly to the grids of the power amplifier Input tubes, practically any number
of power amplifiers may be connected in parallel.

The section on cables and plugs shows methods of connecting amplifiers to
the console.

Replacement parts, with the exception of resistors, condensers, and tubes,
which are standard items and may be purchased from a radio supplier, should
always be ordered from Hammond Organ Company. When ordering, specify
the type and serial mumber of the console or tone cabinet.

When making tube replacement, output tubes in the amplifier should be checked
for similar plate current readings. If tubes have been In service for a con-
siderable length of lime it is usually advisable to change all tubes at one time
rather than to try to match new tubes to the old ones.

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O^ t^ OOEL A CONSOLE

T i nJimvAl li-AhAlDTmrr - IL^ v to JyO LTBafl'l

AO L79£i]-0

P II TONE CONTROL J MCO AO IU»3^£J

PRt-AMPUFiea
f^lCURE L

3-35

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TOTiJTCWS

HEATEK '
1.5 V

.15 MEG.

1 MEQ,

TONE
CONTROL

30 ODD

USED ON" MODEL. A CONSOLE
SERIAL NO. 1574 TO M^l [NCL.

USED ON MODEL B CONSOLE
SERIAL NO. *000 TO 55^9 INCL.

-PRE -AMPLIFIER-
FIGURE i

T i FiUmcnl transftirmr r - 115 v 60 cy AO 17S10-1
T 4 Output Iranslormer - ^q 17826-0

(Primary 1300 ohms)

(SffCDndarv ISohina)
(DC Refci&lancp)

RU TONE CONTROL ,|MEC, AO Z[>?q3-2i

.1 MEG.

.05/400

USED ON MODEL A CONSOLE
SERIAL NO. 245i TO 2&i9 [NCL.

USED ON MODEL fl CONSOLE
SERIAL NO. 5540 TO 593^ INCL.

T 3 F]l*rntnt tiansformer Il5 v bD cy AO 17830^1
T 4 Output Irfinsformer AO i78i6-0

(Primary 130O Qhn^s

Secondary 1^ atuni

□ C RpaisUnce)

RU TONE CONTROL .1 MEG. AO 20^91-^3

PRE -AMPLIFIER

FIGURE 3

3-36

.1 ^;ECi-

«60

H£>TER3
2.3 ^

Sm.(iSiSiSu

imzMV

6 ii5r,A,c, 6

USED IN CONSOLES

MODEL A SERIAL NO,

I5b0 TO Ibib JNCL.

MODEL B SERIAL NO.

5940 TO lOOli INCL,

MODEL C SERJflL NO.

lZO^ TO idll INCL.

MODEL D SEPJAL NO.

] TO liOe INCL.

PLAYER SERIAL NO-

9000 TO 9U3 INCL.

T 3 filamrnt IrsnsEormer
T 4 Output iransformor

(Primary 13DD ohmi)
Setpndarv k^ ahms
DC Re&iatanceJ

PHE-AMPLIFIER
FlCLfRE 4

115 V bO cy AO ITBiO-l
AO ITBit-l

R Jl TONE CONTROL -IN^EC AO Z0;93-2J

.1 MEG.

^12

CONTROL > iO,U0O

J ^-^°"^^"T ww^

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IflPUT

C7 .05/400

.0001

400

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HEATERS

t^5

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21

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Tl»MIIiL FAIJIL

cojj::iN3EHa

USED !N CONSOLES

MODEL A SERIAL NO. 2M7 TO 2711 INCL.
MODEL a SERIAL NO. I003J TO lt£05 INCL.
MODEL C SERIAL NO. l^H TO I^^^S INCL.
MODEL D SERIAL NO. I90g TO 9^ha iNCL.
PLAYER SERIAL NO, 9124 li 9ZlO
MODEL G - ALL

R 11 TONE CONTROL J MEG, AO i0£93'2i

T » Filament trflnrnformer 115 V bO cy AO P83D-I
T 4 Output transEorir.tfr AO 178ifa-l

PRE- AMPLIFIER

FIGURE 5

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\^5V

* PREAPvCPLiFIERi *|7H FOl_LOWINi CODE UARh^ Difftfl A5 fCH^LOWS"
A. CQDE C> AND e^LQV^ - RLSiSTOR^ llnANDnil AA£ .fr MEQ.

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PART NO.

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FIGURE 6

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USED IN MOr>EL E COrJSOLE

SERIAL NO. aOOO TO S47cL INCL,

T 4 Filamrfit transfoTmtr
T 5 Outpul Ir^ntlarrner

R n DUAL CONTROL A

AO 17811-1
MEG_ AO lb^3l"0

PRE AMPLlt^lER
FIGURE 7

3-38

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USED IN ^tODH:L E CONSOLE

SERIAL NUMBER h-i7J TO &'ocl INCL.

T A Oiilpui Trarsfonner AG 17S^6-Q
T 5 FiUmrnt Transformer AO ITSJl-l

R IL Duiil Conlro] .1 MEG, AO 16533-0

PRE J^MPLIFIER
FEGUPF fl

J
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115 T, A,C.

^-} '

6 — 6 O

F CHD c;

USED IN MODEL E CONSOLE

SERIAL NUMBER B^bi TO ^719 INCL.
[C 37 i R 9"* omitted in early )
[pre ampliliers of this series.)

PRE >Mi^LiriER
FIGURE 9

T 4 Output TTflrslurmtr AO 18726-0

T 5 FiUnienl Iranstorm^r AO 17831-1

.1 MEG, DjsI Control AO 16533-0

3-39

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PRE-
AMPLIFIER

VOICE
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VvVvVv

50,000

USED IN POWER CABINETS
A-iD SERIAL 1 TO 999 INCL.
A-4C, B-40 «■ C-40 I TO £^9<* INCL,

L 1 Filler choke 40 ohms
1. 2 Radio frequency cJiokc
T I Power Ir-insformet
T i- Output tran^loriner
(Primary IZO ohms)
(SEcondary 1/I0 ohm)

AG 16682-1
AO 16663 -Q

AO 166S1-1

■A-?0 Cflbinffts SERIAL NO. KbOl
A-40 fr B-40 cHbinets SERIAL NO. 1-1711
have condenser CI A mfd and
rpsiiior R4 .1 MEG.

POWER. AMPLIFIER
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USED [N POTER CABINETS

A-20 SERIAL NO. 1000 AND

T I Powpr iraoaformet AO l6t"'M

T 1 Outpji cranGEormpr AO 16631-1

(Prim, no ohms} „ _ __^-*».**.

(>r-Ci >l ohm* j

L I Filter choke
L 3 R.F, choke

AO lGtBJ-l-2
AO [ 666i-0

ABOVE
2400* ABOVE
3400 TO lOB4t INCL.
2400 jV above
414STO 5510^ mcL.

DR20 SERIAL 15.007 70 22, J99 INCU

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DXZO ALL , . CODOr

A-40
B-40
C-40
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SERIAL
SERIAL
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SERIAL

SPEAKEariELD
230 OHMS

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5000 OHMS

11 PUT COHflCTTCKS

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PR -40, QR-4U TONE CABINET

40 Watt Output
INPUT WATTAGE 220

Equipped with two 15" speakers for bass tones and two
IZ" speakers for the treble tones. They provide three
dimension amplification which creates a beautiful re-
verberation effect in Stereo, These cabineta feature the
new and improved Hammond Reverberation control for
both baiis and treble tones. Convenient outside controls
make it easy to change the degree of reverberation lor
each.

DIMENSIONS: 31-1/2" Wide 37-1/2" High 18" Deep

WEIGHT:

130 Lbs.

PR 40 FRONT

The QR-40 is electricaUy similar to the PR'40 but with
its utility type cabinet Ls only used where appearance
is not a consideration, such as in tone and rever-
beration charnbers.

PR 40 REAR

The treble direct speaker is normally mounted in the
top. In an unusual installation where the ceiling is very
low, or cabinets are stacked or radiation is otherwise
restricted, it is possible to move this speaker to the
hole provided in the front. The metal diffuser in front
of the speaker must also be nnoved, and the wooden
cover must be attached under the lop to close the hole,

DIMENSIONS: 31" Wide 36-5/8" High 17-1/4" Deep

WEIGHT:

Ul Lbs,

QR 40 REAR

QR 40 FRONT

Refer to card on untiervdr of bench top
for cx>tuole iiuuJUtioD and oiling iiuiiuc-

CAUTTOM

PACKING FOR MOVING

OR SHIPMENT

The RcvcrbcTiUon Unit must be locked
before moving cabinet or unit; otherwise.
dcUcatc pjfiB will be damjge<i because of
bouncLUg ol Ehc three coil springs when
hanging free. To lock ihc Reverberation
Unit, inserl screwdriver in «lot it end of
lock rod "A" shown in Fig. I and lum y*
turn counterclockwise If cabinet has rear
grille, an opening is provided in grille
cEoth to allow acce^ to lock rod.
Never remove tubes from cheir sockets
without Erst turning off power at console.

INSTALLATION

Unlock Reverberation ITrji by inserting
screwdriver m slot at end of lock rod "A"
shown in Fig. I and turning */jt turn dock-
wise so that slot IS vertic^. If cabinet ba£
rear grdle, an opening is provided in grille
doth to allow a\:ceBS to lock rod.
Cabinet must be level and must not rock-
Floor musi be farm to avoid vibration.
Connect console-to- ubinei cable u ahown
m Fig. 1.

Additional tone cabineu may be connected
to this unit by using a 5'conductor cabinet'
lo'cabinet cable connected to socket
marked "ADDITIONAL POWER AM-
PLIFIHRS" in Fig L Signal at this poult
comes directly from consijle And does not
have reverberation. If additional cjbmets
are not Type PR or QR, inquire of
youi Hdtnmund dealer or the factory Serv-
ice DepartmciU on use of isolating trans-
former. If total input wattage of all
cabinets exceeds rating on console namC'
plate, auxiUary power relay [iiust be pro-
vided

TONE CABINET INSTRUaiONS

MODELS PR-30 AND PR-40

THRU CHANNELS

The am pilfer in this tone cabinet has three
channels, The ba^ channel drives two
IS' speakers and responds only 1o frc^
quencies below 20(1 cycles. The treble rt-
verbcracion channel dnves the lower 12'
speaker and covers the range above ZOO
cycles. The treble direct channel, driving
the upper 12' speaker, alfio covers the
ra.nge above 200 cycles.

REVERBERATION SWITCHES

The relative amounL of reverberation for
the treble and bass channels can be tc-
lectcd by two recessed switches located
on the side of the cabinet Each switch
has four positions When both switches
are in the OFF puAJiTon, the reverberation
effect IS completely elimLnated and all three
channels carry the direct signal from the
console.

A Reverbcr-ition Switch Kit c-in be ob-
tained tn turn the reverberation effect on
and off from the connolc. Ask any Ham-
mo ikd dealer for deuids.

ROOM SIZE SWITCH

The ruum size control switch located on
the amplifier, "B" lit Fig. I, is provided
with a alut For adjustment of the bass
volume V.) ompensate for variations in
room size. When used in a small room. il
should be adjusted to reduce the basa
volume for beat tonal balance. Approxi-
mate scttinj^s tttt nxims with average fur-
mshing^i will be .is folio wn-

MODEL PR-40

VOIUMF OF ROOM

Dtf*r 16,000 cu. fl.
BtlOato E6.000CU. h
4000 I" BftOO CM. it-
2000 lo 4000 cu- ft-

P0»!1DN OF SWITCH

folly cDuntfrdciCMwiBc
r>cit ttii counrprcEockwiA^

fully clock wiH

MODEL PR-20

volum; of room fosmw of ^wrrcH

over 200Q cu. It. counitfflnc^ivibc

2000 cu, it- at k» clocJiwiK

LOCATION OF TONE CABINET

Th« tuck of thil lone cabinFt must be at
\eist \]/2.'' front the wall in order lo pro*
vide adequa>te vcniilahon. The location of
the Lone cabinet m the room is of great
acouscje importance. Consult a Hammond
service man for recommendations.

T^e cabinet mua( alway* be pUced al
some distance irom the tionsole, not only
for acoustic rca^onj, bui also because the
magnetic field from the amplifier may
produce a hum tn the console circuits if

the two are very close together. In case of
hum^ make certairk that no piece of elec^
tncal apparatus having a strong magnetic
6eld IS close to the console; for cjLjmplc,
an electric dock or a ftuortficcm laghi on
the console can, in some case^, produce a
loud hum in the speakers.

NOTE" — Always supply model designa^
tion and serial number when wnting the
factory regard mg the console or the tone
cabireL This informauon cai^ be obtained
from the nameplatea.

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P4U FRONT

P-40, Q-40 TONE rARTNET

40 Wstt Output
INPUT WATTAGE

Eqtiipped with a two channel amplifierj two 1^" speak-
ers and two iZ'* speakers serving the bass and treble
channels respectively. This lone cabinet in conjunction
with a Haminond tone cabinet with reverberation can
add the additional power required for larger inatal-
laiii>rx at a minitnum cost. Can also be used alone where
sufficient natural reverberation is evident.

DIMENSIONS: 31-1/Z'' Wide 37-1 /Z" High 18'^ Deep

WEIGHT

lib LBS

The Q40 is electrical sinnliar to the PIU but with utility
type cabinet is only used where appearance is not a
cons I de ration 3 uch as
chambers

tone and reverberatvon

The treble speakers are nornrially mounted in the top.
in unusual Installation where the ceiling is very low. or
cabinets are stocked or radiation is otherwise restric-
ted, it is possible to move these speakers to the holes
provided in the front. The metal diffusers in front of
the speakers must^ also be moved and the wooden
covers musr be attached under the top to close the
holes.

DIJ^ENSIONS: Jl" Wide 36-5/8" High 17-1/4" deep

WEIGHT:

no LBS-

P-lt» REAR

Q40 FRONT

Q4U REAR

TONE CABINET INSTRUCTIONS

MODELS P-40 AND Q-40

IMPORTANT

When cabinet is to be shipped, or moved
from room, frgbun nuts at each end of
apnng mounitd amplifier it> picveni
damage

Never remove tubes from their wckrta

without first tUTTimg otf power at console.

Always supply rmidd desiyiutiun and
serial number when *ntmg (actury regard-
ing console uf t^JHC cabinet This mfoTma-
tion can he obtained from namcpVif«.

INSTALLATION

Sei up cabinet lor uperatinn as tullows:

1, Loosen nut at eadi end of amplifier
until amphhei floats frecfy on moununE
iprmgs. Leave ejch nui "n stud wilh
about 1/16" cleanntP to chassLi Fail
Ure to luosen nuts rrtniy cau% hum m
lone cabinel

In cases where amplifier is held dowu
>mch 4 additiondl screws at mrners,
these screws anJ * tapped plates under
neaih shelf aboulJ be removed ind dis-
carded.

2. Connect console to cabinet .ahli" as
aliown in Figure I

y M-'lel Q 40 IS imendcJ for use in rfr
uerberation or lune ch.imbei The iwo
treble ipeaJters are normally mounted
in the lop In im unusual inEtjllaiinn
where ceilms H very tow, i» tabmets
are stacked, ut radiatmn Erom top is
otherwise rcsiriCteJ. *t is possible ti»
move theic spraLers to holes provided
in the front The metal diffusers mual

be moved with the speakers, and
wooden covers from front holes should
then be used to fieal lop holes

Additional tone cabinets mjy be connected

10 this uml by using ^ conductof cabinet
tncdbmet cable connected to socket
ni;irkeJ "AJduional Power Amphfii^rs" m
Fjg I Signal at this point comes direcliy
h'*it\ console

11 total input wattage uf ^U cabinets ex
cceds rating on console na me plate^ aux
diary power relay must be provided

TREBLE AND BASS CHANNELS

The amplifier in this tone cabinet incorpor-
ates dividing networks, so that the two
n" b-isa speakers respond rjnly to fre-
quencies below 200 cycles and the two 1 2"
treble speakers cover the range above 200
cycles.

BASS CORRECTION

''Bass CorrccCion" switi^h on amplifier is
used to compensate for variations m room
size When cabinet is used in a small room,
switch shi>uld be adjusted to reduce ba^
volume for best tonal balance ApproKi
mate settings fui roomi with average
furnishings wi[] be as follows:

(If cabinet is placed in a tone cham-
her^ these figures apply to aiie of
JTStcnmn room )

VOLUME OF ROOM SWITCH PO^mON

Over Ui ,000 cubic leet O

B.OOO to 16.000 cubic feet —3

4,tXW) to S,O0O cuhc feet —6

2.000 to 4.000 cubic feel —10

LOCATION OF TONE CABINET

The back of this tone cabinet must be at
least IJ/2 mches from the wall m order to
provide adequate ventilation.

The location of the tone Cdbinet m the
room IS of ^reat acoustic impnriance. Con
suit a Hammond service man for recjm-
mendations The cabmet must always be
pldced at some distance from the console^
not only for acoustic reasons but alsi.i be-
cause the magnetic field from the amphfier
can produce a hum in the console circuits

nca

if the two are very dose togeeber

In case of bum. makt certain thai no piece
of electrical apparatus liaving a strong
magnetic fcld is close to the coniole; lor
example, an electric cloclt or a fluorescenl
light on the console can. m some cises,
produce a loud hum in the speakers.

Some hum fn the basa channel may be
cduicd by unbdUnced fiVr^ tubes Four
new tubes of same make will generally be
sadslactonly balanced Sometimes hum
level can be leduced by interchanging (iV6
tubes

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PK-20 TONE CABINET

20 Wati Oiitpul
INPUT WATTAGE 18^

Equipped with tvuo IB" Speakt^rs for bass tones and two
IZ" speakers for tht treble tones. They provide three
dimension amphficalion which creates a beautiful re-
verberation effi^ct in Stereo. These cabinets feature Ihe
new and improved Hammond Reverberation control for
both bass and treble tones. Convenient outside controls
make it easy to change the degree of reverberation for
each.

DIMENSIONS: il-1/2" Wide 37-1/2'' High 18" Deep

WEIGHT:

118 Lbs-

PR 20 FRONT

PR 20 REAR

Rffci lo c^rd on under&idf of brn^h lop
for console insE^UUnn and oiling in«ruc-
(ioti5.

CAUTION

PACKING FOR MOVrNG

OR SHIPMENT

The Reverhtranon Unit must be [ixked
beiorc mrjving c^bmcl tir unit; otherwise,
delicite p.iris ^^J|{\ be J,imflgcd betausc ol
bounding iti (he three coti sprmfjs when
hanging free. To I.ktL the Revciberanoti
Unit, irtseit svrtwdnver m slot at end of
lock rod "A ' Rh<*wn in Fig 1 and turn Y*
[urn cGunierizIturttfJiEc It cibinei hjs rear
grille, an opening i5 proMJtd in snilc
cloth to jlhi\v a£i:esA lu lock, rud

Never remove lubes Irom ihfir sockcis
without first turning off p'wer at Lionsulf

INSTALLATION

Unliick Ri-vi'fheriilion llnJi by inserting
screwdriver m slot Jt end of jock rod "A"
*hown in Ffg I ani turning y^ turn duck-
wise su thaJ slot IS vertical If cabinet h.is
ftai grille, <ui upt'inng is provided in i^nlle
dolh Id StWttVf nucess lu lock rod
CibiUfC mmt be level and must n^it ir>ck
Ftfhjr must he tirm lu .ivojU v i brut ion -
GT^neci ^onsolc-iu'cibmci cabli' .is shown
iij tig L

AddilionjI tunc cjbmtta nuj be ^unnected
in [his jnit by usmg a i-coiiducior cabinet
lueabinel LJtile ^oiui^cled to socket
m,irked "ADDITIONAL POWER AM
PLIFIERS" tn Fig. 1 Siguj] jt this porilt
Citmes dtrectly troni omsole -ind dots not
hjvc reverberation. U additional cabinets
jr£ not Type PR or QR, inquire oi
yuur Hatntnoud dealer or the l.iLlory Serv-
ice Department on use vi i*<4iitmg trans
former U total i^ipui WAttago oT all
b>>bLn«':^ esfcieed^ rating un console niirae-
plate^ auKiitary p.jwer relay mu^t be pro-
vided

TONE CABINET INSTRUCTIONS

MODELS PR- 20 AND PR-40

THRIE CHANNELS

The ampliricr in ihis tone c^hiuer hiis ihrcc
c:n;mneU The bass chnnntl dnvcB Twu
I ^ spedk^rs fiuU r4:5p(^nLk only (o (rt-
micQLies bchfw 2rK' cycles The ircblc re-
v^rbi^raliun ch.uinel drives the lower 12^
spe.iktr *uk\ LTtavcrs ihc rjnge -ibove 20U
Lytles The ircble diri:Li channel, driving
iht: upper 12** spi^.ikcr. aIs^^ cover* ihe
rjnge above 20i) cycles.

REVERBERATION SWITCHES

The relative rtniount of reverberation for
the treble ,ind bass ch.mnels can be sc-
lecffd by two recessed swiUhcs lotaied
on thf Side tkf the cabinet T-ith switch
has four pufiitums When both switches
afc in the t)FF piwihon. ihc reverberation
effect is cnmpleicly chmuiiitfd ^ind all three
chjnnels carry the direi:i 5ign>il frnm the
consnk

A Reverberaiiun Switch Kit t,in be ob-
iFuncd tit turn the revrrbcrjtion effect on
and off from (he console Ask any Ham
miiiid dealer for ilel-idv

ROOM SIZE SWITCH

The rodin siiie Cuturi/J swiLch lucAtcJ an
the amphhcr, "D" ni Iig. I, a provided
with I slot for ;idjustmenl of the bass
volume to cimipciisale ^ur vanalions m
room sue When used in a ^mjll roitm, %l
ahuuld be adjusted lo reduce the bj5*
volume lor b.'!ii loniil h.il.iiice Apprmi
mate settin^^i lur rooms with average fur-
iiLshmg.^ Will be ■<& billowy

MODEL PR<40

VOLUME OF ROOM POSIimN Of miKH

uvcr Ih.nnOcu ft. (idly ciiuniFrclcKWf-r

BllOU [M IA,iHlO Cil h lifXt IM CuuriTFrdcKk^tif

^'HlO If, ButiO cu (t licit in cWkwiic

7IXIU lo 40IXJ cu tt fully cluckwi&c

MODEL PR-20
VOLUME OF ROOM PO&ITIOM OF SWITCH

ovrr 2U<KI LU h. t.uuikfcrrl'ikk.4iiic

LOCATION OF TONE CABINET

The back nf ihaa [L>ne cjbiner mu5l be it
least }]/2 from ihc wall in nrder to pro^
vJLle adequate ventiUtJon. The locatmn of
ihe lone cabinet in the ro^nn is of great
acoustic imporLince. C^nsuU a Hammond
icrvice m4n Jor rc^umiDendiiCians

The cabinet musi always be placed ai
some distance froin the cnjistile^ m^ only
for 4LOLL^[ic reus^jn^, but hiIj^o beciuf^ the
mugnetie field hom ihe amphtier may
produce A hum in rhe consule circuits if

the (\un are very clnse together In case of
hum, miike certjin thai no piei;e uf elec-
trics! appar^ituft UjX'iri); -i strong magnctjc
field ]& dose to die coii^oie; for example,
an eleclnc duel ur a fluorescent light on
the cnh&oJe c;io, in some ca^es^ pnxluL-e a
Loud hum 111 the speakers

NOTE ^Always supply m^xlel designa'
lion and serial number when wnung the
factory fcgrtrdmg ihc trunsole ur the (one
cabinet. This fcnJ^prmalioifc ijan be obtained
from the nam^pUtcs.

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NOTE: THE FOLLOWING INFORMATION PERTAINS SPECIFICALLY TO THE

MODELS B-3 & C-3, HOWEVER, DUE TO THE SIMILARITY OF THE CON-
SOLE MODELS IN THIS MANUAL, MUCH OF THE INFORMATION WILL
APPLY TO THEM ALSO.

TROUBLE LOCATION

3-1- TROUBLESHOOTING-

3-2. GENERAL. When troubleshooting, use all
of the aids included in this handbook: block
diagram (figure 3-1), overall schematic (figure
3-3), amplifier schematic (figure 5-10), illustra-
tions of components (figures 1-4, 1-5, and 3-2),

stage (as shown in schematic, figure 3-3). Make
all capacitor checks with capacitor analyzer, if
avLiilable. Always disconnect capacitors before
making tests; otherwise the readings will be
affected by a possible shunt circuit. Replace
any capacitor which shows a deviation of 20
percent or more-

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L-AjD

I VCK UMt

TAfil.E.T

Figure 3-1. Block Diagram of C-3 Console with PR-40 Tone Cabinet

.^ I » ^^!22i

Figure 3-2. Pedal Switch Assembly

and the trouble shooting chart (reference para-
graph 3-28), Before starting an elaborate test
procedure, make a thorougli visual inspection to
locate the fault. Check for defective wiring,
drops of solder, faulty connections, open resis-
tors and capacitors, jammed tone wheels, etc,

3-3. TUBE TESTING. When the trouble is
traced to a specific stage, test tubes in that stage.
If tubes are satisfactory, make a point-to-point
voltage check in accordance with paragraph 3-4,

3^. VOLTAGE AND RESISTANCE MEA-
SUREMENTS- Make voltage and resistance mea-
surements on the individual components of the

3-5. RESISTORS, Resistors used in Hammond
Organs are marked with the standard EIA
(Electronic Industries Association) color code,
as shown in Table IL In this code, the body
color or first color ring (starting from the out-
side edge) indicates the first digit of the resistor
value. The second ring denotes the second digits
and the third ring represents the number of
zeros after the second digit. Thus a resistor
marked with brown, green,- and yellow rings (in
that order) would have a value of 1 50,000 ohms-
Gold and silver rings represent percentage toler-
ance, gold indicating 5 percent tolerance and
silver indicating 10 percent tolerance. Replace

3-69

A"^Hr^"Js^Y aCivti3 43^ Sf^Oi. Nivw

3-70

Figure 1—4. Rear View of Console

3-71

Figure 1-5. Tone Generator

3-72

GUIDE
STOP

LOCKING AND
TRIP ASSEMBLY

PLAYING
KEYS

Figure 1-6. Manual Chassis Partially Disassembled

Figure I— 7. Preamplifier

3-73

3-74

resistors differing by as much as 30 percent from
their rated values.

1 ABLE II -

■ RESISTOR COLOR CODE

0-Black

4-Yellow

1 -Brown

5-Green

2-Red

6-Blue 8-Gray

3-Orange

7-Violet 9AVhite

3-6_ COIL MEASUREMENTS. For the DC

(direct current) resistance value of chokes and
audio transformers, refer to the appropriate
circuit diagram. An open winding in the choke
or transformer will be indicated by no ohm-
meter indication. Check the power and filament
transformers by comparing their measured
voltage with the voltages given in the circuit
diagram. All voltage values are given for a I I 7-
volt (or 234-volt) AC input. If the input volt-
age varies, a corresponding change will be noted.

3-7. SECTIOMALIZING TROUBLE

3-8. AMPLIFICATION SYSTEM TROUBLES.

3-9. Such troubles as loss of volume, poor
quality, excessive hum, noisy operation, or no
signal are usually traceable to the amplification
system. For example, if distortion is noted in
the loud speakers, connect a headset across
terminals marked "G" "G" on the console pre-
amplifier. (See figure 1-7.) If the quality is good
on the headset, the cause of the distortion will
be found in the amplification system following
the console preamplifier. Should distortion
occur at the preamphfier terminals, replace all
tubes. Should distortion in the console preampli-
fier continue, test each preamplifier stage indiv-
idually with the headset. When the defective
stage is located, test each capacitor and resistor
for deterioration.

CAUTION

Insert an 0.1 mfd, 400-volt DC capacitor in
series with the headset to prevent DC volt-
age from damaging it.

3-10. HUM.

3-1 L Hum in the loud speakers may indicate
trouble in the reverberation spring system
assembly. (Reference paragraph 3-28.) If a sus-
tained hum or howl is heard, starting only when
a low note is played at liigh volume, check for
the following:

a. Microphonic tubes in the amplifier. Re-
place all tubes if necessary.

b. Improper grounding of all plug connections
to and from the amplifier.

c. Defective bypass capacitors in the rever-
beration portion of the amphfier,

d. Locked spring system.

e. Improper mounting of the reverberation
unit.

f. Presence of undesirable magnetic fields,
such as motors, generators, supply transformers,
and other equipment generating heavy magnetic
field patterns,

3-12, LOCATING AND CORRECTING DE-
FECTIVE INDIVIDUAL TONES.

3-13, Silent or weak individual tones are usually
caused by defects in the circuit ahead of the
amphfication system. Such defects can be traced
to the tone generator and filter circuits, key
circuits and board connections, and signal wiring
between the manual chassis, generators, and
pedal switch. Trouble occurring over the full
range of tones and present at the input to the
console preamplifier can usually be traced to a
defect in the mixing transformer or associated
circuitry.

3-14. LOCATING DEFECTIVE TONES,

3-1 5, Depress preset key A# on the upper

manual. (See figure 1-1.)

3-16. Pull out the first (No. 1) brown drawbar
only in the first set of drawbars in the left-hand
group,

3-17. Start with the first key, C, (frequency No.
13) of the upper manual and strike each higher
note on this manual in succession. Tlie last note
at the right end of the keyboard is C (frequency
No- 61). Note the frequency numbers of all
weak or dead notes. Table III indicates all key
numbers and notes and the corresponding fre-
quency numbers for each drawbar,

3-18. Return the first brown drawbar to its
original position and then pull out the last white
drawbar only, in the same drawbar set. (Refer-
ence paragraph 3-16.) Start at the second C note
(frequency No. 61 ), and strike each higher note
on the upper manual in succession until the
second F# note from the top of the keyboard
is reached. This F# note corresponds to fre-
quency #91, the highest frequency produced
by the generator. Note the frequency number
of all weak or dead notes.

3-19, Repeat the procedures of paragraphs 3-15
to 3-1 8 inclusive, on the lower manual. Use the
No. 1 brown and No. 9 white drawbars in the
first set of drawbars in the riglit-hand drawbar
group.

3-75

TABLE III - FREQUENCY NUMBERS ASSIGNED TO KEYS AND PEDALS

^Frequency

■ number

assigned to keyboard harmonics

Key

Drawbar 1

Drawbar 2

Drawbar 3

Drawbar 4

Drawbar 5

Drawbar 6

Drawbar 7

Drawbar 8

Drawbar 9

No.

Note

subfund.

SiJb-3d

fund.

2d harm.

3d harm.

4th harm.

Slhharm.

6 th harm.

Slhharm.

Gif

3-76

TABLE III ' FREQUENCY NUMBERS ASSIGNED TO KEYS AND PEDALS

(Continued)

"Frequency

' number ,

assigned to Keyboard harmonics

Key

Drawbar 1

Drawbar 2

Drawbar 3

Drawbar 4

Drawbar 5

Drawbar 6

Drawbar 7

Drawbar 8

Drawbar 9

No.

Note

sub fund.

sub-3d

fund.

2d harm.

3d harm.

4th harm.

5th harm.

6th harm.

8th harm.

3-77

TABLE 111 - FREQUENCY NUMBERS ASSIGNED TO KEYS AND PEDALS

^Continued)

Frequency numbers assigned to Pei

ial harmonics

Pedal

No.

Note

Fund.

3d harm.

2d harm.

4th harm.

6th harm.

8lh harm.

1 0th harm.

1 2th harm.

—

S3,

*These frequency numbers are assigned arbitrarily for convenience and are not related to the actual
frequencies.

3-20. If ail notes are uniform in intensity or
change evenly from note to note, the tone
generators are operating normally. However, if
notes are weak or absent, proceed as directed
in paragraph 3-2 L

3-21- CORRECTION.

3-22. A single dead or weak note which occurs
on one manual but not on the other, may be
caused by a fault in the key contacts. To correct
this fault, adjust the bus bar shifters associated
with the pedal switch and both manuals as
directed in paragraphs 4-9 to 4-13 inclusive.

3-23. A single weak or dead note occurring at
the same point on both manuals may be caused
by a defective generator, a broken wire, or a
poorly soldered joint on the terminal strip. Test

the generator for output by fastening a short
length of wire to the 6th bus bar, from the
bottom, on the preset panel; then touch the
other end of the wire to each lug on the gener-
ator terminal strip. If all notes sound, the cable
wire or soldered joint is at fault and must be
repaired. If no generator output exists, either
the filter circuit or the magnet pickup coil may
be defective, or the tone wheel is not rotating.
3-24. Figure 3-4 illustrates the position of each
filter reactor and capacitor on the generator
cover. Fasten a short piece of wire to the 6th
bus bar, from the bottom, on the preset panels
and test each terminal of the filter. (Reference
paragraph 3-23.) If the filter is at fault, replace
the defective component as described in para-
graphs 5-86 and 5-87.

3-78

□F TRANSFORMERS

MOTOR END

FILTER TPAHSFDR>^eR6

ST*RTlt4<i
MOTOR END

AS 7B a ^ a 71 n 4T Zfl tj 4 aa SI t* s? 3a « n so ^a tt h h ^>. 73 tt * a w s a si za m i^ 7$ i^ ji i? &a a y.?.** _ ' »

O. JOC JJOOSUg Q J □ 'J ? 3 O ■? !■ J 3 g a| ^~Q" O Q OoOQOaOPQQJUCPQOCiQO CU P OOOPOOPOPOO b ^XjQnnQQ Q.g. q t i. Q ■ 0_i^.. 9_J_O OOOOOQOP OOgpJ
AS 30 U C 30 M J3 ^9 *:: 7t I- 5L 11 fc9~3 4S » fil 2 W V t7 ? 91 ft* 2* 60 4i 77 |7 S3 14 70 JO 4t 27 ti a 47 flO ?0 St ^7 73 li 45

OUTPUT TERMfhiAL FRtQUENCV NJLJMBE-RS

Figure 3-4. Location of Filters on Tone Generator

3-25, If there is no signal across the magnet
pickup coil terminals, even with the coil discon-
nected, either the coil is defective or the associ-
ated tone wheel is not turning. Check the pickup
coil by unsoldering its lead and, with a short
piece of wire, connect the lead to the prei^et
paneh (Reference paragraph 5-6,)

3-26. When there are two dead notes on each
manual, determine which frequencies are at
fault, as described in paragraphs 3-14 to 3-20
inclusive. Figure 3-5 illustrates the exact location
of the magnet associated with each frequency;
the dotted lines connecting the frequency num-

bers indicate that they are generated by two
tone wheels on the same shaft and in the same
compartment {It should be noted that, with
few exceptions, tone wheels on the same shaft
differ in frequency numbers by 48.) On fre-
quency numbers 37, 38, 39, 40. and 41 , only a
single active tone wheel is on each shaft. If the
2 magnets associated with the dead notes are
together, 1 tone wheel is probably jammed
against the magnet tip. To correct this condi-
tion, proceed as follows:

a. Loosen the set screw on the magnet to be
adjusted, then move the magnet back sliglitly,

@ ^

>^ ,K^ .^ '\@ \@ '\@ '\® \@ \@ \@ \@ \@ \

®\ @\ @\ @\@'\®'\®\ ®\ ®\ @\ ®\ ®\ Q
© ®®(V)©0© ©@ ®®©

BACK VIEW OF MAIN GENERATOR

FRONT VIEW OF MAIN GENERATOR

(NUMBERS SHOWN ARE FREQUENCY NUMBERS.)

Figure 3-5- Generator Magnet Locations

H
O

3-79

Do not twist it,

b. Strike the proper playing key. The note
should now sound.

c. To make the final adjustment, strike and
hold down the playing key for the note being
adjusted. Then tighten the magnet slightly in
position and tap it gently until it moves close
to the tone wheel to bring the intensity up to
the intensity of the adjacent notes. Tighten the
set screw so that the magnet is held firmly in
position.

d- Do not remove main tone generator assem-
bly from the console unless absolutely necessary.
Should this be necessary, proceed as directed in
paragraphs 5-63 to 5-71 inclusive.

3-27. TROUBLESHOOTING CHART,

3-28. The following troubleshooting chart
contains general information to aid in the loca-
tion of trouble. When the trouble stage is sec-
tionalized, refer to Section V for detailed aid in
identifying the trouble with a particular part.

SYMPTOM

PROBABLE CAUSE OR REMEDIAL ACTION

L No Signal

Check the source of supply; a 1 1 7-volt, 60-cycle
(or 234-voIt, 50-cycleV AC power source is re-
quired. Check the power and connecting cables
for secure mounting, good contact, and broken
pins. Oieck the power supply voltage in the tone
cabinet. Check all vacuum tubes.
Connect output meter across the console pre-
amplifier output terminals. If no output is ob-
tainedj conduct a point-to-point voltage test on
the defective unit.

Check the signal input to the power amplifier
and compare the reading with the console pre-
amplifier output reading on the output meter.
Tliese should be ideniical. If no output reading
is obtained, conduct a point-to-point voltage
test on the defective unit.

Check the power amplifier output. If no output
reading is obtained, conduct a point-to-point
voltage test-

2. Loss of Volume, All Notes

Low voltage, source of supply.

Check the console preamplifier output voltages.

Qieck the power amplifier output voltages.

Qieck all vacuum tubes. (Reference paragraph

3-3_)

Low voltage from power supply.

Conduct a point-to-point voltage test and check

for defective components.

3, Loss of Volume, Single Note

Dust or accumulation of dirt on contact; make
adjustment, (Reference paragraphs 4-9 to 4-13
inclusive.)

Poorly soldered connection or high resistance
contact in console wiring. Trace the signal in-
tensity througlaout the circuit by means of
high-impedance headset (circuit to ground). As
an alternative method, attach one end of an
insulated test lead (48 inches long) to 6th bus
bar from bottom, on preset panel, and use other
lead end to trace the signal intensity throughout
the manual wiring.

3-80

4, Poor Quality

Use low volume, and check the console pre-
amplifier output with high impedance headset.
Check all vacuum tubes.
Make a point-to-point voltage test, (Reference
paragraph 3-4.)

Qieck individual components for defects, espec-
ially audio bypass capacitors and frequency
filters.

Be sure that the voice coils are not rubbing
against pole pieces.

5, Excessive Hum

Check all connecting plugs for loose connections.

Check wiring connections in cable plugs.

Check for defective filter capacitors in power

amplifier.

Check all vacuum tubes. Replace if necessary.

Remove all inductive electric or electronic

equipment in the vicinity of the console cabinet.

Check all bypass capacitors, particularly on

cathode-to-ground circuits.

Check ground connection from generator to two

halves of lowest preset panel bar-

6. Rattle or Intermittent Operations

Loose connections between cable connectors.
Loose cable connections in connector plugs-
Damaged speaker cone.
Voice coil rubbing on pole piece.
Defective vacuum tube-
Check lubrication.

Check the individual felt pad used on each manual
key or bass pedal to absorb the striking sound.
Check for intermittent resistors or capacitors by
lightly tapping suspected components.
Check the suspension of the reverberation spring
system assembly.

Adjust the bus bar shifters. (Reference para-
graphs 4-9 to 4-13 inclusive.)

7- Miscellaneous

a. Howl, or unwanted sustaining of tone Check reverberation unit locking lever. (Refer-

ence paragraph 2-6.)

b. Bass pedals release sluggishly Check and increase tension of leaf springs at end

of bass pedals.

c. Preset keys fail to release properly Replace leaf bracket and associated leaf spring;

replace key if necessary. (Reference paragraphs
5-73 to 5-75 inclusive and see figure 1-6.)

3-81

HAMMOND ORGAN COMPANY

REPAIR

AMD

^ A ^ ^ 1

EMBIY

VIBRATO

A N M 1

ERS

(A) Although this technical bulletin is based on scanner repair^ it is not the
single source of vibrato problems. Check existing switches, vibrato pre-
amp, (tubes, etc), phase shift line box, and cables both to and from the
scanner.

(B)

SYMPTOM

CAL'SE 1 ^t:?AlR 1

(1) Dead

(la) Vibrato Switch

Cb) VlbrLCo pce-aitp. (Tub^^s, etc.)

<c) Opea Signal Wire to Line-box

(d) Open Troa Scanner shielded cable.

(la) Replace Switch

0>) Replace tubes oc other
defective coinponents.

(c Replace vires or repair
& d) conitections.

(2) Choppy Vibr»to

(2a) Short«d capacitors on lice-box

(b) Open colle ou iioe box

(c) Oil saturated bakellCc Insularors which
pick up Inpuritlea and short out tLe
■stationary plates to the main aficenibly
chaasla oE scanner.

(d) Rotor plates rubbing against the stationary
plates Inside scanner.

C2a) Replace defective com-
& b) ponenta

(c) Clean Stationary and rotor
platec and replace lns:jlat-
ors, isolating the otatlonary
places from the ^risin chassis.

(d) Check enO play end height of
rotor on gear dnd shaft
asaetnbly.

(3) Slow Vibrato

(3a) Seml-Crosea bearing on gear and shaft assdobly

(b) Poor tension on drive springs of the gear
and shaft assembly.

(3a) Check oiling threads and
for proper oiling.

(b) Replsce gtjar and shaft
casembly.

(A) Ho Vibrato

(4) Frozen bearing on g&ar and shaft aAAsmbXy

(4) Replsiie gear ^r-.d shaft
assembly .

(5) Squeaking Sound.

1
i

{5a) Tension springs of the carbon brushes nla-
positloned causing the brushes to iLske a
fl<lucaklQg sound agalnct the rotor contact ptna.

(b) Dry bearings

(5a) Heat spring connection
with soldering iron and
spring will fall into its
proper position.

(b) Check for proper oiling.

3-82

PARTS LIST

Syn. Motor & Scanner

B Oil Cup Assembly

064-016844

Oil Felt

D Felt Retainer Spring

012-002996

Screws (3)
Screws (2)

Shielded lead and Cover Assembly

066-033247 and 066-033248

H Brush Lug & Insulator Assembly

End Brush Spring Assembly

066-016821

Brush Assembly

066-016958

K Screws (2)

846-040314

Screw (1)

M Housing Cover Assembly

N Screw (4)
Cable Clip

Stationary Plate (16)

066-016829

Q Rotor Assembly

066-016828

R Screws (16)

816-080720

Insulators (16)

036-016747

Insulators (16)

045-021942

U Front Plate Assembly

V Bristol Set Screw (2)

999-002032

W Gear Housing Assembly
X Screws (4)

Gear & Shaft Assembly

018-033192 and 018-033193

3-83

SCANNER REMOVAL. DISASSEMBLY AND REPAIR PROCEDURE

Q) DETACH MOTOR AND SCANNER ASSEMBLY (A) FROM THE GENERATOR ASSEMBLY BY REMOVING FOUR
NUTS FROM THE SYNCHRONOUS MOTOR WHICH ANCHORS THE MOTOR TO THE L" BRACKETS OF THE
GENERATOR ASSEMBLY,

(4)

(2)

(3)

(5)

(6)

REMOVE THE CABLE CONNECTIONS IN THE ORGAN SO MOTOR AND SCANNER ASSEMBLY IS FREE FROM
ORGAN,

NOTE A. C, LINE BOX, AND OUTPUT CONNECTIONS FOR REASSEMBLY.

LOCATE OIL CUP (B) AND OIL FELT (C) INSIDE CUP, THE OIL FELT MUST BE REMOVED AND THE

COTTON THREADS UNWRAPPED FROM THE FELT BEFORE SEPARATING THE SCANNER AND MOTOR, REMOVE

FELT RETAINER SPRING CD) AND LIFT UP ON THE FELT TO REMOVE THE THREADS, (DO THIS VERY
CAREFULLY TO AVOID BREAKING THE COTTON THREADS!.

AFTER REMOVING THE THREADS FROM THE OIL FELT TAKE A PICK OR A PAPER CLIP AND REMOVE
THE THREE THREADS FROM THE ONE SIDE OF THE OIL CUP BY PULLING THEM THROUGH THE HOLE IN
THE CUP. THE THREAD FROM THE OTHER SIDE OF THE CUP NEED NOT BE REMOVED.

LOCATE SCREWS (E) WHICH HOLD THE MOTOR AND SCANNER ASSEMBLY TOGETHER. REMOVE THE SCREWS

AND PULL THE MOTOR AND SCANNER ASSEMBLY APART. NOTE: THERE IS A GEAR ON THE END OF THE

MOTOR SHAFT AND MUST BE GUIDED THROUGH THE HOLE OF THE SCANNER HOUSING TO SEPARATE THE
MOTOR AND SCANNER.

REMOVE TWO SCREWS (F) FROM THE REAR COVER (G) OF THE SCANNER. BEFORE REMOVING THE COVER
NOTE THAT THERE IS A SHIELDED WIRE ATTACHED TO THE COVER. THIS WIRE IS CONNECTED INSIDE
THE SCANNER AND THERE IS VERY LITTLE SLACK IN THE WIRE. REMOVE THE COVER AND TIP IT BACK
CAREFULLY SO YOU CAN SEE INSIDE. LOCATE THE CARBON BRUSH AUDIO PICK-UP ASSEMBLY (J),
THE CARBON BRUSHES MUST BE REMOVED BEFORE THE MAIN HOUSING ASSEMBLY COVER (M) IS REMOVED,
IN ORDER TO PREVENT DAMAGE TO THE CARBON BRUSHES AND TENSION SPRINGS. LIFT END BRUSH U)
AND SLIP THE TWO CARBON BRUSHES (H) OFF THE ROTOR CONTACT PIN. <BE EXTREMELY CAREFUL OF THE
ROTOR CONTACT PIN DURING DISASSEMBLY 50 YOU DO NOT BEND OR BREAK THE PIN).

3-84

(7)

(8)

(9)
(10)

(11)

(12)

(13)

SHOULD IT BE NECESSARY TO REMOVE THE CARBON BRUSH AUDIO
PICK-UP ASSEMBLY (J), DESOLDER THE AUDIO WIRE FROM THE
BRUSH ASSEMBLY AND REMOVE THE TWO (2) SCREWS (K) ■ TO RE-
MOVE THE END BRUSH (I) REMOVE SCREW (L) AND SEPARATE FROM
THE BRUSH ASSEMBLY.

REMOVE THE FOUR (4) SCREWS (n) AND SLIP THE HOUSING COVER (h) OFF THE MAIN ASSEMBLY.
NOTE; MARK THE HOUSING COVER CM) AND THE MAIN ASSEMBLY CHASSIS (U) TO INDICATE THE START-
ING POINT OF THE SCANNER CABLE, ALSO MARK THE LOCATION OF THE CABLE CLIP (0).

STATIONARY PLATES (P) AND ROTOR (Q) ARE MOUNTED ON THE MAIN ASSEMBLY CHASSIS (U). REMOVE
TWO (2) OF THE STATIONARY PLATES (P). BY REMOVING SCREWS (R). WHEN REMOVING THE STATION-
ARY PLATES FROM THE ASSEMBLY YOU WILL NOTICE THAT THERE ARE INSULATOR (S) AND (T) ON BOTH
SIDES OF THE MAIN ASSEMBLY CHASSIS, INSULATING THE STATIONARY PLATES FROM THE ASSEMBLY (U).
THEN REMOVE THE ROTOR ASSEMBLY (Q) BY LOOSENING THE TWO (2) BRISTOL TYPE SET SCREWS (V),
TO AVOID DAMAGING THE ROTOR CONTACT PIN DURING DISASSEMBLY.

REMOVE THE REMAINING (14) STATIONARY PLATES AND INSULATORS-
CLEAN THE STATIONARY PLATES, ROTOR PLATES AND OTHER METAL PARTS USING A FREON SPRAY OR
OTHER CLEANING SOLVENTS THAT DO NOT LEAVE ANY RESIDUE AFTER DRYING. AN ABSORBENT CLOTH
OR SWAB CAN BE USED IN CONJUNCTION WITH THE CLEANER.

SPRAY METAL COATED PARTS WITH KRYLON CORONA DOPE (cLEAR)

TO GET ON OIL THREADS OR ROTOR PICK-UP PIN.

CAUTION: DO NOT ALLOW SPRAY

IN MOST SCANNER REPAIR YOU NEED NOT GO FURTHER IN DISASSEMBLY THAN STEP NUMBER ELEVEN (11)
BUT SHOULD CONDITIONS WARRANT FURTHER DISASSEMBLY CONTINUE WITH NUMBER (i3)/ OTHERWISE
INSTALL NEW INSULATORS AND REASSEMBLE THE SCANNER.

IN REMOVING THE GEAR HOUSING ASSEMBLY (W) THERE ARE FOUR (4) SCREWS (X) HOLDING THE
ASSEMBLY ON TO THE MAIN ASSEMBLY CHASSIS <U). UPON REMOVING THE GEAR HOUSING ASSEMBLY
YOU WILL NOTICE THE BAKELITE GEAR AND SHAFT ASSEMBLY (Y) . THE SPRINGS ON EITHER SIDE
OF THE BAKELITE GEAR ALSO INTERMESHES WITH THE METAL GEAR OF THE SYNCHRONOUS MOTOR TO
DRIVE THE SCANNER.

(14) TO REASSEMBLE THF SCANNER REVERSE THIS PROCEDURE.

3-85

3-86

SECTION IV

NOTE- THE FOLLOWING INFORMATION PERTAIN SPECIFICALLY TO THE MODELS B-3 & C-3.

HOWEVER, DUE TO THE SIMILARITY OF THE CONSOLE MODELS IN THIS MANUAL, MUCH
OF THE INFORMATION WILL APPLY TO THEM ASLO,

ALIGNMENT PROCEDURES

4-r PRESET PANEL TONE SELECTION.

4-2. The preset keys shown in figure 1-2 are
used to select the ready-mixed tone colors. Nine
color-coded wires from each preset key are
fastened to the bus bars of the preset panel by
slotted screws. Each group of nine color-coded
wires is fed through individual holes below the
preset panel. The color coding of each group is
identical to the color coding of the nine wires
from the drawbars (above the preset panel). ^Fhe
drawbars can be withdrawn to numbered stops.
The frequency relationship of the wire color
coding is indicated below. Note that the color
sequence is the same as the EIA color code for
resistors.

Brown Sub-fundamental

Red Sub-3rd harmonic

Grange Fundamental

Yellow 2nd hannonic

Green 3rd harmonic

Blue 4th harmonic

Violet 5th harmonic

Gray 6th harmonic

White 8th harmonic

4-3. The tone color or quality of any note,
played on either the upper or lower manual, is
determined by the intensity of the harmonics
in relation to the fundamental note as selected
either by the preset key or drawbars. The num-
bers of the preset panel and drawbars indicate
a progressive increase in intensity, starting from
(drawbar fully pushed in) to 8 inclusive. Any

tone color may be identified by a number con-
taining 9 digits, each digit representative of the
intensity of the fundamental tone or 1 harmonic
as selected on the drawbars or preset panel.

4-4. The Hammond Organ has its preset panel
arranged to make available to the organist ton-
alities similar to those ordinarily found in the
small church or chapel pipe organ, as well as
tones for religious services and congregational
singing, without the use of the adjustable draw-
bars. Table IV illustrates the approved preset
panel arrangement for chapel organs. Remove
the rear panel of the console, examine, and
check the preset panel to determine that the
preset panel corresponds exactly to Table IV.
Change the position of any lead by loosening
the slotted screw which secures it in place, re-
moving the lead, and then securing it in correct
position by means of the slotted screw provided.
Refer to figure 4-K

4 5. ALIGNMENT OF COIL ASSEMBLIES,

4-6. Each magnet and coil for each tone wheel
is mounted in the tone generator as a single
assembly. {See figure 5-1,) To locate and deter-
mine which coil assemblies require alignment,
proceed as follows:

a. Remove the console rear panel.

b. Connect an output voltmeter (1 ,000 ohms-
per-volt scale) across the two terminals marked

TABLE IV - HAMMOND ORGAN PRESET DATA

UPPER MA>a]AL

LOWER MANUAL

Preset Keys

Equivalent _ ^ ..^
r, , ^ . Tone Qiiality
Drawbar Setting

Value

Preset Keys

Equivalent
Drawbar Setting

Tone Quality

Value

Cancel

00 5320 000 Stopped Flute

cif

00 4545 440

CeUo

00 4432 000 Dulciana

PPP

00 4423 220

Flute & String

00 8740 000 French Horn

00 7373 430

Clarinet

00 4544 222 Saliciona]

00 4544 220

Diapason, Gamba and Flute mf

00 5403 000 Flute 8' & 4'

00 6644 322

Great, no reeds

00 4675 300 Oboe Horn

00 5642 200

Open Diapason

00 5644 320 Swell Diapason

00 6845 433

Full Great

£f

00 6876 540 Trumpet

00 8030 000

Tibia Clausa

32 7645 222 FuU SweU

42 7866 244

Full Great with 16'

fff

Adjust harmonic drawbars for 1st

Adjust harmonic drawbars for 1st Group,

Lower

Group, Upper Manual

Manual

Adjust harmonic drawbars for 2nd

Adjust harmonic drawbars for 2nd Group

, Lower

Group, Upper Manual

Manual

4-1

O Q * J imI -J

c. Set both tlie vibrato controls, and all per-
caission tablets, to their ''OFF'' positions-

d. Depress the swell pedal to the position of
maximum volume.

e. Disconnect tone cabinet from console.

f- Connect one end of a test lead to the 5th
preset panel bus bar, from the bottom.

g. Place the organ in operation.

h. Check the AC input voltage at the console
preamplifier terminal board; the voltage should
be 1 17 volts or 234 volts. Any variation of in-
put supply voltage will give a corresponding
increase or decrease of reading, as shown in
Table V.

i. Check the output voltage of each coil
assembly by touching the prod end of the test
lead to each terminal in turn on the main gen-
erator terminal board. Tlie frequency numbers
are not indicated. For location of exact fre-
quency, see figure 3-4.

j. Compare each voltage obtained with the
appropriate voltage listed in Table V, Do not
try to adjust to these voltages unless the values
deviate more than 30 percent.

4-7. If it is ascertained that the coil assembUes
require alignment, proceed as follows:

a. Disconnect the generator assembly only
when absolutely necessary. Make adjustments
from the rear whenever possible. Do not remove
the cover as this necessitates unsoldering and
resoldering 91 leads, in addition to realigning
all coil assemblies.

b. Refer to figure 3-5 and determine which
coil assemblies require alignment.

c. Loosen the set screw which holds the coil
assembly in position.

d. Compare the intensity of the note associ-
ated with the aligned coil with the intensity of
adjacent notes.

e. Tap tlie coil assembly gently until it moves
close enough to the tone wheel to bring the in-
tensity up to the intensity of the adjacent
notes, pull coil assembly back, if necessary. Do
not turn magnet during this operation.

f. Tighten the set screw.

CAUTION

These coil assembhes are locked into posi-
tion at the factory and seldom require
adjustment. Do not pull back with a twist-
ing motion, as damage will result.

TABLE V
GENERATOR OUTPUT VOLTAGES

Freq.

Output

Freq.

Output

Freq.

Output

Freq.

Output

No.

(V)

No.

(V)

No.

(V)

No.

(V)

9.8

2.7

1.2

1.6

11.5

2.5

1.6

2.25

1.4

1.5

1.4

1.2

1.8

8.5

1.8

1.2

1.8

1.2

14.5

0.8

0.6

9.5

1.8

0.7

1.5

0.4

0.6

0.5

0.7

2.5

0.5

2.2

0.3

2.5

88
89
90
91

0.4
0.2
0.5
0.25

4-3

4-8. ADJUSTMENT OF PERCUSSION CUT-
OFF CONTROL. This control, located in the
preamplifier (See figure 1-7) should be read-
justed whenever control tube V7 is replaced.
Set expression pedal wide open, both volume
tablets to "Normar\ percussion tablet '^ON",
and harmonic selector in cither position. Play
any key in upper half of upper manual, hold it
down at least 5 seconds, and then adjust per-
cussion cut-off control exactly to the point
where the signal becomes inaudible,

4-9. ADJUSTMENT OF INTERMITTENT OR
NON-OPERATING KEYS.

4^10, Scratchy, noisy, or silent keys may result
from accumulations of dust which lodge in the
contacts. To correct this condition, strike the
key 15 to 20 times in a rapid staccato manner
to dislodge the dust particles and to clear the
contacts.

4-1 L If this procedure does not dislodge the
dust particles, adjust the bus bar shifters. (See
figures 1-4, 3-2, 4-2, and 4-3.) Bus bar shifter
"A", located beliind the mixing transformer,
adjusts the bus bars associated with the keys of
the upper manual; bus bar shifter "B" adjusts
the bus bars associated with the keys of the
lower manual; bus bar sliifter ''C" adjusts the
bus bars associated with the pedal keyboard.

4-12, Turn the proper bus bar shifter about two
turns in either direction. Tliis operation permits
the key contacts to strike a new position on the
bus bar and should free all contacts of accumu-
lated dust particles.

4-13- If, in extremely stubborn cases, the pro-
cedure above does not dislodge the dust par-
ticles, use a board to depress one octave of
notes (7 white and 5 black keys) and then
adjust the bus bar sliifters while holding the
keys down.

BUS BAR
SHIFTER

Figure 4—2. Manual Assembly, End View

PEDAL SWITCH CABLE

(TO GENERATOR TERMINAL STRIP)

SWITCH
CONTACTS

RESISTANCE WIRES
(FROM SWITCH CONTACTS TO TERMINALS)

KEY CONTACT
SHIFTER

Figure 4-3. Pedal Switch Assembly, Cover Removed

4-4

SECTION V

NOTE. THE FOLLOWING INFORMATION PERTAINS SPECIFICALLY TO THE MODELS B-3 & C-3.

HOWEVER. DUE TO THE SIMILARITY OF THE CONSOLE MODELS IN THIS MANUAL, MUCH
OF THE INFORMATION WILL APPLY TO THEW ALSO.

STAGE DATA AND FINAL TESTING

5-r DETAILED THEORY OF OPERATION,

5-2, MAIN TONE GENERATOR ASSEMBLY.

5-3. The main tone generator assembly consists
principally of 48 rotating sub-assemblies (each
subassembly consists of a shaft, 2 disks called
tone wheels, and a bakehte gear), and a drive
shaft which extends the entire length of the
generator. This drive shaft is resiliently coupled
at one end to a starting motor and at the other
end to a synchronous nm motor (reference
paragraph 5-12), and is divided into several
sections connected by semi-flexible couplings,
(See figure 1-5 J A series of 24 driving gears, 2
each of 1 2 sizes, is mounted on this shaft,

5^. Twenty-four of the 48 rotating subassem-
blies are mounted on each side of the drive shaft
so that each of the driving gears engages 2 bake-
lite gears associated with opposite rotating sub-
assemblies. These bakelite gears rotate freely
with the tone wheels on separate shafts and are
connected to their respective assemblies by a
pair of compression-type springs. The bakelite

gears are provided in 12 different sizes corres-
ponding to the 1 2 driving gears of different sizes,
Consequently, 4 of the tone wheel subassem-
blies, each containing 2 tone wheels, operate at
each of 12 different speeds. Each driving gear,
with its associated bakelite gears and 4 tone
wheels, is contained in a separate compartment,
magnetically shielded from the rest by steel
plates which divide the generator into a series
of bins. (Sec figure 5-2.) All four tone wheels
in any one eompartment run at the same speed,

5-5. Each tone wheel is a steel disk about 2
inches in diameter and contains a predetermined
number of liigh and low points on its outer edge.
(See figure 5-L) Each high point is called a
tooth. There are 12 wheels with 2 teeth, 1
wheel to operate at each of the 1 2 speeds
(reference paragraph 5-4); similarly 12 wheels
each have 4 teeth, 8 teeth, 16 teeth, 32 teeth,
64 teeth, and 128 teeth; also 7 tone wheels have
192 teeth- A 2-tooth wheel and a 32-tooth
wheel form an assembly, giving 2 frequencies,
4 octaves apart. The 4- and 64-tooth wheels

MAGNET

OME SIE>C OF COIL GROUNDED

COit

COIC OUTrtJT TEWMIKAL

TOME WHEEC

TONE GENERATOR

tone: VsyutLL'S

M*».^r*cy

ZOlfL.

BAMLiTt ttAR

nAGM

OAKtLiTt Ct*^R

DRIVI>4G GEAR

SECTION OF MAIN GENERATOR

Figure 5 — \. Construction of Main Generator

5-1

4 AND 64

16 AND BLANK

4 AND 64
16 AND 192
4 AND 64

16 AND BLANK

4 AND 64

16 AND 192

4 AND 64

16 AND BLANK

4 AND 64
16 AND 192

4 AND 64
16 AND 192
4 AND 64

16 AND BLANK

4 AND 64
16 AND 192

4 AND 64

16 AND BLANK

4 AND 64

16 AND 192

4 AND 64
16 AND 192

2 AND 32

8 AND 128
2 AND 32
8 AND 128

2 AND 32

8 AND 128

2 AND 32

8 AND 128

2 AND 32

8 AND 128

2 AND 32

8 AND 128

2 AND 32
8 AND 128

2 AND 32

8 AND 128

2 AND 32

8 AND 128

2 AND 32

8 AND 128

2 AND 32
8 AND 128

NOTE=

NUMBERS REFER TO
THE NUMBER OF
TEETH ON EACH
TONE WHEEL.

Figure 5-2. Tone Wheel Tooth Count in Generator

5-2

are assembled together, as are the 8- and 128-
tooth wheels and the 16- and 192-tooth wheels.
Five 16-tooth wheels are mounted with blanks
to maintam the balance of the rotating unit.
(See figure 5-2,) Only 91 frequencies are re-
quired for the organ; for identification purposes
these frequencies are numbered 1 to 91 inclusive,

5-6. A magnetized rod, about 4 inches long and
1 /4 inch in diameter, is mounted near each tone
wheel (See figures 5-1 and 5-2.) A small coil of
wire is wound near one end of the magnet. The
tip of the magnet at the coil end is ground to a
sharp edge and mounted near the edge of the
associated tone wheel. Each time that a tooth of
the wheel passes the rod, the magnetic circuit
changes and a cycle of voltage is induced in the
coil. The voltage is very small and is of known
frequency. The frequency is predetermined by
the number of teeth and tlic speed of the rota-
ting tone wheel. Larger coils are used witli tone
wheels of lower frequencies to provide good
low frequency output, but smaller coils are
used with tone wheels of higher frequency to
prevent excessive losses.

5-7. Copper rings are mounted on certain low
frequency coils for the purpose of reducing
harmonics. The eddy current loss in such a ring
is small for the fundamental frequency of the
coil, but is higli for its harmonics. As a result, the
the relative intensities of any harmonics which
may be produced by irregularities in the tone
wheels are reduced,

5-8. Tlie edge of each tone wheel and the tip
of each magnet are coated with lacquer to pre-
vent corrosion, for, should oxidation set in, the
change in tooth shape would introduce unde-
sirable frequencies-

5-9, Filters for eliminating spurious harmonics
from the generated simple tones are located on
the top of the main tone generator, and consist
of filter capacitors and reactors. (See figure 3-4.)
(Ttiese capacitors and reactors are tuned ujiits
and are called tone generator filters.)

5-10. The tone generator filters have a single
tapped winding. Tliis tap is grounded and one
side, which is connected to the associated coil
assembly through a capacitor^ forms a resonant
circuit for the fundamental frequency of that
coil. Harmonics are supressed. The capacitors
for frequencies 49 to 54 inclusive are 0.255 mf,
and the capacitors for frequencies 55 to 91 in-
clusive are 0.105 mf. Both capacitors and re-
actors are used with frequencies numbered 49
to 9! inclusive. On frequencies 44 to 48 inclu-
sive, the capacitors arc omitted, but the reactors

used have a greater number of turns. Below
frequency 44, neither capacitors nor reactors are
used; a length of resistance wire shunts each gen-
erator output. This resistance wire is wound on
the appropriate magnet coil.

5-11. The tone generator filters are mounted on
top of the generator at an angle to minimize re-
action between them. Wires connect the filters
to the coil assemblies and to the terminal strip
on the generator. Ninety-six terminals are pro-
vided on this strip; 3 terminals are grounded to
the generator frame and serve to ground the
manuals and pedals, and 91 terminals carry the
various frequencies,

5-12. The start motor is a shaded-pole induc-
tion motor. The synchronous run motor (used
on 60 cycles) has a 2-pole field and 6-pole
armature^ and a synchronous speed of K200
rpm (revolutions per minute). For 50 cycles, a
4-pole armature is used which has a speed of
1,500 rpm. When the organ is placed into oper-
ation, the start switch is first operated to apply
power to the start motor. The rotor of the start
motor slides endwise and engages a pinion on its
shaft which a gear on the generator drive shaft.
(See figure 5-3.) When the "RUN" switch is
operated, wliile the start switch is held in '^ON"
position, power is apphed to the synchronous
run motor and a 250-ohm resistor (1,000 ohm
for 234 volts) is connected in series with the
start motor, thus reducing the driving power of
the start motor. Because of the braking action
and the loss of power of the start motor, tlie
system slows down to, and locks into, synchro-
nous speed; the mn motor then begins to carry
the load. When the "START'' switch is released
and springs back into position, the start motor
disengages from the drive shaft by action of a
spring assembly, and stops.

5-13. The spring couplings of the motor shaft,
the flexible couplings between the sections of
the drive shaft, and the tone wheel spring cou-
plings are provided to absorb the variations in
motor speed. Tlie synchronous motor operates
with a series of pulsations, one each half-cycle.
If the tone wheels were coupled rigidly to the
motor, this irregularity would carry extra fre-
quencies into each tone wheeL The spring sus-
pension system for supporting the main tone
generator minimizes the transmission of mechan-
ical vibration between the console cabinet and
the main generator.

5-14. VIBRATO EQUIPMENT,

5-15. The vibrato effect is created by a periodic
raising and lowering of pitch, and thus is funda-

5-3

PINION

LUBRICATING
WICKS

Figure 5— 3. Starting Motor

mentally different from a tremolo or loudness
variation. It is comparable to the effect pro-
duced when a violinist moves his finger back and
forth on a string while playing, varying the fre-
quency while maintaining constant volume.

5-16. Tlie Hammond Organ vibrato equipment,

as shown in simplified block diagram, figure
5-4, varies the frequency of all tones by con-
tinuously sliifting their phase- It includes a
phase sliift network or electrical time delay
line, composed of a number of low pass filter

sections, and a capacity type pickup or scanner.
which is motor-driven so that it^scans back and
forth along the line.

5-1 7. Electrical waves fed into tJie line are
shifted in phase by each line section (the amount
per section being proportional to frequency), so
tliat at any tap on the line, the phase is retarded
relative to the previous tap.

5-18. The scanning pick-up traveling along the
line will thus encounter waves increasingly re-

SfGNAL FROM
riRST SECTION
OF PREIAMPLIFIER

AMPLIFlER|-p[

SECTJONS OF VIBRATO LINE

hrCZHZZh-C^MZZhrCZhK

x:-

MZZM

AMPLIFIER

SIGNAL TO SECOND

SECTION OF PREAMPLIFIER

Figure 5-4. Fundamental Diagram of Vibrato System

5-4

tarded in phase at each successive tap. and the
signal it picks up will continuously change in
phase. The rate at which this phase shift occurs
will depend on how many hne sections are
scanned each second,

5-19, Since a cycle is equivalent to 360 elec-
trical degrees, a frequency shift of 1 cycle
occurs for each 360 electrical degrees scanned
per second. For example, if the scanner passes
over the line at such a rate that 3.600 electrical
degrees are scanned each second, there will be
a frequency change of 10 cycles,

5-20. For the widest vibrato, the whole line is
scanned from begijining to end in about 1/14
second, and this rate of change of phase causes
about 1-1/2 percent decrease in frequency. Note
that the frequency remains constantly 1-1/2
percent low as long as the moving pick-up re-
tards the phase at a constant rate.

5-2L Since the pick-up sweeps from start to
end of the line and then back, it increases the
frequency by an equal percentage on its return
trip, the average output frequency remaining
equal to the input frequency. The exact amount
of frequency shift depends not only on the
amount of phase shift in the line but also on tlie
scanning rate. This rate, however, is constant
because the scanner is driven by the synchro-
nous running motor of the organ,

5-22. The degree of vibrato (or amount of fre-
quency shift) may be varied by a switch (not
shown in figure 5-4) which causes the whole
line to be scanned for No. 3 (wide) vibrato,
about half of it for No. 2, and about one-third
for No, 1 ,

5-23. A vibrato chorus effect, similar to the
effect of 2 or 3 slightly out-of-tune frequencies
mixed together, is obtained when the vibrato
output signal is mixed with a portion of signal
without vibrato. For vibrato chorus, part of the
incoming signal appears across the vibrato line
and the rest across a resistor in series with the
line. As the vibrato effect is applied to the part
of the signal appearing across the line, but not

to the part appearing across the resistor, the

combination produces a chorus effect- For nor-
mal vibrato, this resistor is short-circuited. In
the iVlodel C-3 console the vibrato effect can be
applied to either manual separately or to both
at once.

5-24. Figure 5-5 shows the vibrato line box.
Each of the inductance coils is connected with

one or more capacitors to form one filter
section-

5-25. Figure 5-7 shows the construction of the
vibrato switch.

5-26. Tlie scanner, shown in figure 5-6, is
mounted on the main generator synchronous
motor and driven at 412 revolutions per minute.
It is a multi-pole variable capacitor with 16 sets
of stationary plates and a rotor whose plates
mesh with the stationary ones. In figure 5-7,
Index B, two sets of plates have been removed
to show the rotor.

5-27. Signals coming from the line through the
vibrato switch appear on the stationar>' plates
and are picked up, one at a time, by the rotor.
Connection to the rotor is made by carbon
brushes, as shown in figure 5-6, Index A, Two
brushes touch the sides of the contact pin and
a third presses on the end, in order to eliminate
the possibility of contact failure.

5-28. Figure 5-8 shows the vibrato circuit.

5-29. Tlie vibrato switch has no "OFF" posi-
tion, and 3 vibrato chorus positions (CI, C2,
and C3) are included in it as well as the 3
vibrato positions (VI, V2, and V3), The vibrato
effect is turned "ON" and ''OFF" for each
manual separately by means of "VIBRATO
SWELU^ and "VIBRATO GREAT" tablets on
the manual assembly.

5-30. Tlie preamplifier used with this circuit
has two separate channels into wliich signals
from the "VIBRATO GREAT" and "VIBRATO
SWELL" tablets are fed. (Reference paragraph
5-37.) The "VIBRATO" signal goes througli a
preliminary amplifier, through the vibrato

► 1

^f5PH^

4^?^*fT>!^ '^

Figure 5—5. Vibrato Line Box

5-5

ROTOR CONTACT PIN

ROTOR INSULATOR

END BRUSH MOUNTED
ON LEAF SPRING

SIDE BRUSH
TENSION SPRANG

2 SIDE BRUSHES

ROTOR PLATES

STATIONARY PLATES

A-BRUSH COVER REMOVED TO SHOW BRUSHES

B-V*EW WITH SCANNER COVER REMO/ED .
[2 SETS Of PLATES REMOVED TO SHOW ROTOR)

FIXED CONTACTS
CONNECT TO
LINE

CONTROL
KNOB 5HAFT

CAM SHAFT

Figure 5—6. Vibrato Scanner

MOVING CONTACTS CONNECT
TO SCANNER

'CH0RUS''C0NTACT

(bottom VIEW WITH COVER REMOVED)

CABLE
TO LINE

TO SCANNER

Figure 5—7, Vibrato Switch

5-6

T>H V lOHT<CT4 ClQK ,

V>PoaiTID*4Svj 4.-4 Cl /

— VllWATO PHASE SHIFT i.|h,£

Figure 5—8, Schematic Diagram, Vibrato System

system, and then into additional stages of
amplification- The "NO VIBRATO" signal
also has a preliminary amplifier, but bypasses
the vibrato system and goes directly into the
additional amplifier stages.

5^3 1 - MANUAL CHASSIS ASSEMBLY.

5-32- The 9 contact springs on each key are
connected by resistance wires to the proper
terminals on the terminal strip and carry the
harmonics of the particular note with which
they are associated. (Reference paragraph 1-20.)
The resistance wires avoid overloading of the
generators and thus allow each generator to be
used independently to feed a number of key
circuits- All key contacts are aiive at all times,
When a playing key is depressed, its 9 frequen-
cies are impressed on the 9 bus bars of the
manual. No wires are connected to these bus
bars; a preset or adjust key must be depressed
to complete the circuit. (See figure 3-3,) Each
preset or adjust key is provided with 9 contacts
identical to those on the playing keys and is
further provided with a locking and tripping
mechanism, the purpose of which is to permit
only 1 preset or adjust key to be in operation
at a time. (See figure 1-6.) The cancel key re-
leases a depressed preset or adjust key; this
cancel key has no contacts.

5-33- Flexible wires connect the 9 contacts of
each adjust key (A# and B) to the 9 drawbars
contolUed by the key. The wires are color-coded

for identification. Each drawbar makes contact
(according to the stop position to which it is
drawn) with any one of 9 bus bars connected to
taps on the mixing transformer. (See figure
3-3.) The bus bars correspond to different in-
tensities of sound,

5-34. The 9 preset keys (C^ to A) are connected
by flexible leads to the preset panel in the back
of the console. (See figure 1-4.) The preset panel
consists of 2 sets of 9 bus bars which correspond
to those in the drawbar assembly and which are
connected to the same taps on the mixing trans-
formers,

5-35. Tlie mixing transformers are mounted on
the manual chassis assembly as shown in figure
1-4, Shielded leads carry the signals from the
secondaries of these transformers to the pre-
amplifier.

5-36, PEDAL SWITCH ASSEMBLY, The pedal
switch assembly is similar in operation to the
manual chassis assembly (reference paragraphs
5-3 1 to 5-35 inclusive); the pedal switch assem-
bly, however, contains only 4 bus bars instead
of 9- A flat spring at the end of each pedal of
the detachable pedal clavier depresses a small
plunger, as shown in figure'3-2, on tht: pedal
switch assembly and actuates a double set of
contact springs, thus making eight contacts
available for each note The pedal contact
springs are connected by decoupling resistance

5-7

wires to terminals. A cable connects those ter-
miiKils tlirougli i\ wiring tube lo the proper
terminals on the main lone generator strip. The
pedal switcli bus l>ars are connected, by means
of four colored wires, through a filler reactor
and resistor network to the pedal drawbars-
(See figure 5-^),) The reactor and resistors filter
out undesirable higlier harmonics and serve to
balance the pedal tones.

TERMINALS

INSULATING
BUS BAR
SEPARATOR

BASS PEDAL
SWITCH PUSHER

^RESISTANCE
WIRES

SWITCH
CONTACT

Figure :>-9. Pedal Switcli Contacts

5-37. VOLUME CONTROL AND PRE-
AMPLII ILR ASSLMBLY.

5'3S. Typical Circuit Before Pre-ampliPien

5-3y. Lacli voltage o!" predetermined tVequcncy
produced hy the tone generator Is connected to
one or more key contacts. When the associated
playing key is depressed, this voltage is impressed
upon tile bus bar and is carried Ihrough The pre-
set key switch to the preset panel. The voltage
is then ted to one of the several taps uT the mix-
ing trajisformcr which is associated witli the
manual being phivcd. From the high impedance
secondary of the luixing translormer, tliis volt-
age (combuied with others which may be ted
through simultaneously) passes lo one of the
preamplilier input circuits. (Vibrato "ON'' or
"OFF^^ circuit),

5-4(J. Power to operate the preaniplificr and
power ampliller is supplied through the run
switcli circuit as shown in figure 3-i.

5-4L Preamplirier Circuit, Input.

5-42. I he signal I roni each mixing transformer
is sent li> the VihraU) "ON-OFF^^ tablet associ-
;iicil Willi IIn particular nunuah ,uul is (hen
carried to ihe "VIHKATO^ ur "^NO VIliKAlO"
prcaiuplilier iripul, depending i>n tlic position
of the tablet

5-43. 1 he mput cfrcuil> arc suiiilar, wiHi t-Mie

extra stage of amplification in the "VIBRATO"
channel lo compensate for the loss that occurs
through the phase shift network and associated
scanner- The input tube V4 receives the signals
from ^A'lBRATO" and ^^NO VIBRATO" cir-
cuits and further amplifies them. The signal
then is impressed on the '^LOUD" stator of the
volume control, and on the ''SOFT" stator
through a compensating network.

5-44. Volume or Swell Control.

5-45. Tlie volume control is activated by the
swell pedal connected by an appropriate linkage.
(Sec figure i-4-J Tlie volume control assembly
consists of two sets of stator plates, similar to
tliose used in the scanner assembly. (See figure
5-6.) A rotor assembly of similar size is moved
by the swell pedal and is capable of meshing
with either stator or a portion of each. The
degree of Jiiesh determines the strength of the
entire signal.

5-46. The signal is further ampUned by the
second section of V4 and sent to driver tube
V3 which in turn drives the 1 2BH7 output tube.

5-47. PLRCUSSION SYSTEM. (See figure 5-3.)

5-48. The "Touch Response" percussion feature
is controlled by four tilting tablets (t^igure I-l),
It is available only on the upper manual and only
when the ''B" adjust key is depressed. Percus-
sion tones are produced by borrowing the sec-
ond or third harmonic (depeiidiiig on position
of the "Percussion Harmonic Selector" tablet)
from the corresponding drawbar of the upper
manual '^B" adjust key group, amplifying it,
returning part of it to the same tir:iwb:ir. and
conducting the balance tbrougli push-pull con-
trol tubes which, when keyed, cause the signal
to fade away at a prc-determined rate.

5-4^). With the percussion tablet on, *'B" adjust
key pressed, and an upper manual playing key
pressed, the second or third harmonic signal
goes to percussion input terminal II on the pre-
amplilier chassis and is amplified by T4 and T5.
Tlie percussion input transformer T5 not only
provides pusii-pull signal for the control tube
V7 but also has a third winding which feeds
signal back to the ^nd or 3rd harmonic draw-
bar through ctiuivalcnt key circuit resistor R50
ami terminal """J".

5-50. When a key is depressed, the note first
sounds huully, after passing through the control
tube V7, transformer Tf), a high pass filler, and
terminal L) to ilic grid of V4. Immeduilcly, ca-
pacitor C3 1 in (he control tube grid circuit
begins to discharge, causing the signal to lade away

5-5 L This circuit works as follows: Terminal
K (Approximately -25 volts) is connected to
the 8th harmonic "B'' adjust key drawbar wire,
which is connected through the adjust key con-
tact to the manual bus bar- Pressing any upper
manual key connects this bus bar to a tone gen-
erator terminal and virtually grounds terminal
K through the tone generator filters. This vir-
tually grounds the plate of V6, stops conduc-
tion, isolates the cathode of V6, and thus
isolates the grid circuit of control tube V7, Tlie
grid then drifts from about -25 volts to about
-1 5 volts, at a rate determined by the time re-
quired for C31 to discharge through R57 and
R58. At the completion of this sequence, the
percussion signal is blocked so that it is no
longer audible.

5-52. No further percussion signal can be
heard until all keys of the upper manual are
released so that the control tube V7 grids can
again drop to -25 volts (the rate of this drop
is fixed by the time required to charge C3!
to -15 volts through R55 and R56). Thus the
percussion effect is heard only when keys are
played in a detached manner; that is, when
all keys are released before pressing the next one

5-53, REVERBERATION UNIT. (See figure
1-10.) This device simulates musically desirable
echoes in a large room. An electrical signal
from the amplifier is applied to the driver coil
in the reverberation unit, which converts the
electrical signal into a twisting movement of
3 coil springs. This motion is transmitted
along each spring to a pickup unit, where
part of it is converted back to electrical en-
ergy. The remaining portion is reflected back
to the driver and again back to the pickup
after a time interval determined by the spring
length. This reflection process continues until
the signal level is reduced to about one mil-
lionth of its signal value so that it is no longer
audible. The springs are different in length and
thus there are 3 separate sets of echoes, each
repeated a number of times. Electronic ampU-
fication circuitry associated with the reverber-
ation unit is contained in the power amplifier,
described below.

5_54, POWER AMPLIFIER, (See figure 5-^100

5-55. This is a 3-channel ampHfier with 2
treble channels (one for non-reverberated and
one for reverberated signal) and a bass channel,
with a cross-over point of 200 cycles. Each
channel has two 6BQ5 output tubes with self-
bias. Each treble channel drives a 12" speaker,
and the bass channel drives two 15" speakers
in paralleL

5-56- The power supply unit is a separate
chassis housing the power transformer, recti-
fier tubes, filter, and input connections for
power and signal, A 6-pin plug engages the
console cable, and a 5-pin receptacle is pro-
vided for pkigging in additional tone cabinets,
The console cable consists of 5 conductors;
2 for AC power, 2 for push-pull signal, and
ground.

5-57. The push-pull signal from the console
(Gl and G2) drives treble input tube VI. Re-
sistance-capacitance filters ahead of VI filter
out signal frequencies below 200 cycles. VI
drives output tubes V2 and V3 of the treble
direct channel. It also drives double triode
tube V9 wliich, in turn, drives the reverbera-
tion unit.

5-58. The output of the reverberation unit
passes through transistor TR-K and part of the
signal goes to the treble reverberation switch.
This adjusts the amount of reverberated signal
going into VIO, which drives output tubes VI 1
and VI 2 of the treble reverberation channeL
The switch, in its "off position, picks up
signal from input terminal Gl, in order to
make use of the channel for non-reverberated
signal when the treble reverberation is off.

5-59. Both treble channel output transformers
have tertiary windings which supply inverse
feedback signal to the cathodes of the output
tubes,

5-60. A portion of the output of transistor
TR-1 goes to double triode tube V4, which is
connected as a phase splitter to drive the push-
pull bass channel. The output of V4 goes to
the bass reverberation switch, which is also
connected to the input terminals Gl and G2,
The bass channel receives a large amount of
reverberated signal along with some direct sig-
nal in the "HI" position, only non-reverberated
signal in the ''OFF" position, and varying mix-
tures in the intermediate positions.

5-6 1 . A filter network following the bass rever-
beration switch filters out signal frequencies
above 200 cycles. Following it is a "room size"
switch which can be used to provide better bal-
ance by reducing the bass volume when used in
a small room. The signal then feeds push-pull
tubes V5 and V6, which drive the bass output
tubes V7 and V8.

5-62- REPLACEMENT OF COMPONENTS
5-63, TONE GENERATOR ASSEMBLY

5-64. Remove the four hexagonal-head bolts
and their associated springs and T-washers which

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5- 10

Figure 5 — 10, Schematic Diagram, Power Amplifier

secure the generator assembly to the console.

5-65. Remove the four screws from the left and
right-hand side panels of the music rack- Tilt the
bottom of the music rack by Lifting the side
panels, and remove the rack by pulling outward.

5-66. Remove the 4 chassis bolts fundemeath
the console) and the 2 machine screws (under
the front lower manual rail) that hold the entire
manual chassis in place-

5-67. Disconnect the 79 manual leads, 68 pedal
leads, 4 ground wires, and the pedal filter leads-
The pedal filter is located on the rear surface of
the upper manual assembly.

5-68- Pull out all drawbars to position 8, and
then tilt the manual chassis from the front as
far as the top of the console will permit. Place
suitable wedges or blocks on both sides of the
manual chassis to hold it in this position- The
manual chassis must be tilted to provide ade-
quate clearance for the bolts in the corners of
the main generator assembly,

5-69. Unhook the four suspension springs on
which the generator assembly rides.

5-70. Lift up the generator assembly and re-
move it at the rear of the console,

5-71. Install a replacement generator assembly
by reversing the procedure given above for re-
moving it-

5-72- MIXING TRANSFORMER ASSEMBLY.
The Assembly of two mixing transformers is
provided complete with all leads to the preset
panels, and can be removed as follows:

a. Remove the rear panel.

b. Remove the two screws which secure the
transformer cover in place.

c- Label and disconnect all leads from the
mixing transformers where they connect to the

preset panels.

d. Unsolder green and yellow shielded wires
at mixing transformers.

e. Remove the two wood screws which secure
the mixing transformer assembly to the manual

chassis block.

f. Secure the replacement mixing transformer

assembly in place by reversing the procedures
given above.

5-73. PLAYING KEY.

5-74. Replacement of playing key on upper
manual will be accomplished as follows:

a. Remove the four screws from the left and
right-hand side panels of music rack. Tilt the
bottom of the rack by Ufting the side panels and
then remove the rack by pulling outward.

b. Remove the 2 wood screws and the 2 oval-
head bolts from the ends of the drawbar base-

c. Lift and block up the entire drawbar base.

d. To remove a black key, loosen its key

mounting screw, unhook key from screw, and

hft out key.

e- To remove a white key, loosen its key

mounting screw and those of adjacent black
keys. Unhook these keys from screws, push
them back, and hft out white key,

f. Insert a replacement key and install by
reversing the directions given above for removal.

g. Adjust the tension of the replacement
playing key by comparison with the adjoining
key-

5-75. Replacement of playing key on lower
manual will be accomplished as follows:

a. Remove the four screws from the left- and
right-hand side panels of the music rack. Tilt
the bottom of the rack by lifting the side panels
and then remove the rack by pulling outward.

b- Remove the two oval-head bolts from the

ends of the stop base.

c- Pull out all drawbars to position 8.

d. Tilt the upper manual as far back as the
top of the console will allow, and then wedge
or block it in this position,

e. Complete the replacement of the playing
key on the lower manual by following the same
procedure ^ven above for upper manual keys.

5-76. PEDAL SWITCH ASSEMBLY.

5-77. Replacement of pedal switch assembly
will be accomplished as follows:

a. Remove the pedal clavier by lifting it up
in front and then pulling suraiglit back. (See
figures 1-3 and 3-K)

CAUTION

Be careful to prevent damage to the de-
licately constructed pusher levers (switch

pushers) at the end of each pedaL

b. Unsolder the pedal cable wires from ter-
minals on the generator,

c- Disconnect the brown and black leads from
the filter located on the rear surface of the up-
per manual assembly,

d. Disconnect the orange, red, and yellow
pedal signal leads from the resistor strip on the
rear surface of the upper manual assembly.

e. Use small wooden blocks to raise and sup-
port the entire console a few inches off the floor
to provide the necessary clearance for the re-
moval of the pedal switch assembly.

L Loosen and remove the screws which hold
the wiring tube (through which the pedal wiring

5-11

cable passes to the tone generator) to the con-
sole shelf, the 3 oval-head and 1 hexagonal-
head screws which hold the pedal switch in
place, and the screw which holds the swell pedal
rod in place.

g. Lift the cover board and remove the screws
which hold the pedal switch assembly to the
back rail of the console-

h. Loosen the large bolt at each end of the
pedal switch assembly, then remove the nuts
attached to these bolts. Drop the assembly
carefully and remove it.

L Install a replacement pedal switch assembly
in place by reversing the procedures above.

5-78. MANUAL CHASSIS-

5-79. Replacement of manual chassis will be
accomplished as follows:

a. Remove the rear panel of the console.
(Reference paragraph 1-10.)

b- Remove the four screws on the left- and
rig!\t-hand side panels of the music rack.

c. Lift the side panels to tilt the bottom of
the rack, and then remove the rack by pulhng
outward.

d. Remove the 4 chassis bolts (under the con-
sole) and the 2 machine screws (under the front
lower rail) that secure the entire manual chassis

in place.

e. Disconnect all preamphfier leads.

f. Loosen set screw in expression control
lever arm and detach arm from preamphfier.

g- Remove preamplifier from shelf after tak-
ing out mounting screws-

h. Unsolder (do not cut) the 79 manual leads,
2 ground leads, 3 pedal signal leads (red, orange,
and yellow), and the pedal filter leads (brown
and black),

i. At the power terminal panel, unsolder the
five wires leading to the manual chassis start and
run-motor switches. Determine these leads by
tracing the leads from the switches,

j. Detach pilot lamp bracket by removing

two wood screws.

k. Unsolder eight scanner wires from ter-
minals on back of drawbar base.

L Unsolder brown wire from vibrato Hue.
m. Tie the disconnected cables to the chassis
to prevent damage to the other console com-
ponents when the manual chassis is removed.

n. Remove the m^inual chassis through the
rear of the console. Slide the chassis out care-
fully. Because of frame construction, the chassis
will drop suddenly before it is entirely out of
the console. Two men are required to remove
the manual chassis from the console.

o. Install a replacement chassis by reversing

the procedure above. (See Figure 2-2 for cable
connections).

5-80. SWITCHES FOR START AND RUN
MOTORS.

5-8 L The switches for the start and run motors
are both mounted on the same metal plate; the
following replacement instructions are equally
applicable to each:

a. Remove the black bakehte switch handle
by unscrewing it in a counter-clockwise direc-
tion,

b. Remove the round knurled nut which holds

the switch to the metal plate,

c. Remove the four oval-head screws which
hold the switch plate to the music rack.

d. Remove the rear panel of the console.

e. Unsolder the leads (from the defective
switch) at the power terminal panel on the gen-
erator. (See figure 2-1.) One lead (black) is
wired to the start switch. Four leads, 1 yellow,
1 black, I blue, and 1 brown, are wired to the
run switch, (See figure 4-1.) Unscrew or un-
solder jumper wire between switches,

f. Remove the tape which secures the wires
together. Unbraid the wires connected to the
defective switch up to the manual chassis so
that the switch can be removed-

g. Pull out the switch. Note the position of
the switch with respect to the color of the wires

so that the replacement switch will be installed

in the correct position,

h. Install the new switch in the proper posi-
tion. Braid and tape the wires carefully so that
they will not interfere with the operation of the
generator run motor,

i. Solder the leads of the replacement switch

to the power terminal panel.

j- Operate the switch to determine that it has

been installed properly,
k. Replace the rear panel.

5-82. START MOTOR (See figure 5-3).

5-83. Replacement of the start motor will be
accomplished as follows:

a. To make the start motor accessible, follow
the procedure for removing the main tone gen-
erator. (Reference paragraph 5-63.)

b. Remove start motor capillary threads from
oiling trough-

c. Disconnect the leads to the start motor at
the power terminal panel on the generator.

d. Using a socket wrench, remove the two
start motor mounting screws.

e. Secure a replacement start motor in posi-
tion by reversing the procedures above,

5-84. RUN MOTOR AND VIBRATO SCANNER
ASSEMBLY. (See figure 2-1.)

5-12

5-85. Replacement of run motor and vibrato
scanner assembly will be accomplished as
follows;

a. Remove the rear panel,

b. At the power terminal panel on the gen-
erator, unsolder the red and black wir^s which
lead to the run motor that is to be replaced.
(See figure 4-1.)

c. Unsolder 7 scanner wires from terminals
on back of stop base and 2 scanner wires from
line box,

d. Remove shielded lead attached to "SCAN
at preamplifier,

e. The running motor is secured by four ma-
chine screws to the generator frame. Remove
the nuts and lockwashers, and then disengage
the flywheel coupling springs.

f. Remove the entire motor and scanner
assembly by means of a gentle pull,

g. Secure a replacement motor and vibrato
scanner assembly in place by reversing the pro-
cedures above.

5-86. TONE GENERATOR FILTERS.

5-87. Filters used for frequencies numbered 49
to 91 inclusive, as referenced in paragraphs 5-9
to 5-1 1 inclusive, are resonant reactor-capacitor
units, and will be replaced as follows:

a. Unsolder all leads-

b- Remove the two screws holding the filter.

c. Remove the component,

d. Replace the component by reversing the
procedures above.

5-13

5-14

PARTS ORDERING INFORMATION

When ordering replacement parts from the Hammond Organ Company, the
following guidelines should be observed:

1) Address all parts orders to:

HAMMOND ORGAN COMPANY
PARTS DEPARTMENT
4200 W. DIVERSEY
CHICAGO. IL. 60639

2) All orders should specify the model and serial numbers of
the instrument that is being serviced. (Note: On late
model instruments the model and serial numbers are printed
on the tag attached to the underside of the organ keyboard

3) All orders should specify the Hammond part numbers of the
desired parts.

)

All orders should provijie a specific description of the
desired parts. (For example: Power transformer, 15 volt
zener diode, F through B key module, etc.)

6-1

THIS SECTION IS DIVIDED

INTO THREE PARTS

A. B-3/C-3/PR-40 Complete Parts List

Models

C. Early Tone Cabinets Parts List

NOTES:

1. Part A contains items common to all models, please refer to this list first.

2. Assemblies not shown are no longer available.

3. Items without part numbers are NLA.

4. Parts listing does not insure availability.

6-2

TABLE OF CONTENTS - A
B-3/C-3/PR-40 PARTS LIST

MAJOR ASSEMBLY

PAGE

(TJ) CABINET PARTS (MODEL B-3) 6-5

(7?) TONE WHEEL GENERATOR 6-6

TONE BAR ASSEMBLY

(k^ UPPER 6c LOWER KEYBOARD ASSEMBLY 6-8

(Th KEYBOARD BREAKDOWN 6-9

Q PEDAL KEYBOARD ASSEMBLY 6-10

(T^ PEDAL SWITCH ASSEMBLY 6-11

@ PREAMPLIFIER ASSEMBLY 6-11

iQ START/RUN SWITCH CONTROL PANEL

@ EXPRESSION PEDAL ASSEMBLY 6-15

@ PR 40 POWER AMPLIFIER ASSEMBLY 6-19

(le) REVERBERATION UNIT (NECKLACE TYPE) 6-20

^7) CABINET PARTS (MODEL C-3) 6-21

PRESET PANEL ASSEMBLY 6-13

VIBRATO LINE BOX 5-13

6-14

PR 40 TONE CABINET 6-16

PR 40 POWER SUPPLY ASSEMBLY 6-17

8 J C-3 PARTS CALLOUT (REAR VIEW) 6-22

(PARTS LIST FOR EARLY CONSOLES BEOINS ON PAGE 6-23)

(PARTS LIST ON EARLY HAMMOND TONE CABINETS BEGINS ON PAGE 6-31)

6-4

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FIGURE 1

FRONT VIEW - B-3 (WALNUT

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6-5

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6-6

FIGURE 3

DRAWBAR ASSEMBLY COMPLETE

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3-11

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UPPER 5rOP SWITCH CHA»*CL .......,,-. v Oil-O^H^l

BUSB*R P*NEL *aa USEDI OJ^-OaaJH

BUSBARS (UPPER DfiAW&flftS ) - . , OJO-Ol-frtQ^

BULBARS < LDWER-PEDALJ -,....<--.,,. (139-OlSlWi

BlTSBAFJS 1NSULAIDH5 <2Z USED > 0^1-02047^

STOP PANfL tREJW C£NTEft> U> 0*^-U21890

SCREW , flift-O-iO^l^

STOP PANEL REAP UJ .-,.,,,,. 04S-fl318B9

WASHER 9*J9-0(M)n5

NUT *i99-noini

COKTACT . 00fl-0?0?7i

^-n scR€w

« - A

3-13

3-W
3-i5
3- It

STOP PANEL FRONT U) . - -

t ^ >

STQf' P*NtL (FIWMT CEtJTER (IJ

SLIDER WITH CONTACT

SLIDER DNLV

3-L7 SCHEU iDRAiMBAR KNOfit

3-lS DPU^HAIi HNDB5

OiJ-OZlftflB
060-0 IbbOl
028-036401
«W^J30^J4

SEE FIGURE 4 IhUNUAL ASSV 1

6-7

IS 45 19 40 20 25 46 43 12 II 10 42 41 35

28 29 30 31 32 33 34 47 44 47

36 16 17 15 14 13 I 2 3 4 5 6 7 8 39 38

26 27 21 22 23 24 9 37

FIGURE 4

MANUAL ASSEMBLY COMPLETE

a- I (Wilt *'C" tfv . _ . ..... ttib-tii^f-fyb

ft. 3 WHTTF: "D" key ....... lll-^-OlShfiV

ft- I WHin "E^' KCV a2^-0l^h*tf

4^ f. itHiTl F- <HPt 0?^-OI5hf>9

4- ^ WhlTF "G" «V Oa^.'Ol^ftVO

4- b WHITE ■■*" KEY . , - . , - - »2^-tn'tb7i

A- 7 WHITE "B" KEV ... 02i-OJ'.'-Tj

4- BLfcCrt SK*BP t^tf .... n?5-01frJfl^

.*- a smlTE "CK" KE» - , . - .... OJ5-0lSf'M

i-ll) BULK B ™«F1 KlY . , . O7V0l^hfl2

1-|] BLAtH "A" PHESO MY - 0?^-ajihBI

4-IJ BLACK "G" FUESrr WT .... . U2^-U3i6««

*-U BLACK "F" P11ESET HE* . , . . . - liT-ti \^bJS

l» ^i, BLACK "E" PHESET KET ... 0?",-()l^ri 7S

4-IS BL>CK "0" MIESET KEY , - . . 0^'s-0^^^'7

4-lfc BLACK "C'PRESET W» , . . , 0?Vn3S*i;(i

4*ir WIIU SH*fiP TOF^n KEY .... U/^-(m3<t|1

fi'Pa S^lTCh TAB - VOLUME ...... RJ^-DlWl^b

i-n SWSICH UB VIBWAID SVtLL - . - , , 0?S-UI(,O^J

4-/D SWTTCH TAB - VIBRATO fiRlAT OJi-DlhO^fl

t-i?| WITCH r*E - PEJ*CU5S10N ON QFf . , . , , 0?$-03^0'*1

4-J? SWITCH TAB - PEBCUMION VOLUME . 07^'OJhOft^

fi'*1 SWITCH TAB PEPCU&SION DEC*T OJ-j-JI U>Oft:/

4-iv

XNOB -

i- w

KNDB

^'?yj".

h'U

KNOB -

?v , .

t-J2

HJd(» -

i-a/5" .

4-JJ

KNOB -

1-1/3' .

't'ii KNDB - a- BPOWH

A- ift LEFT HAND EMD&LOCK

h^l/ RISHT HAND CNDBLDCK

I.- W FRONT 5TH1P iHET^ifflN HflNUAlS>

t-|o fBONT STPIP (LOWER HATflJAL^

i-iO HANLAL HATCHlNe TT^ANSFORHEW -

*-Al WJ>*il*AP ASSEMBLY CO^fCrTE

£i-4.' STOP SLIDER ASSEMBLY -

4-41 VIBRA*D CHWUS Sli^lK" PLATE , ,

4-44 PEfiCUSSlDN CQNITKIL SWITCH ASSEWLY

4-4^ MAWiAL CONTTJOL SWITCH ASSEMBLY

4-46 VIBRATO SWHCH ASSfUBLY

4*47 TOGGLE SPHlNG H EACH SWITCH! .

'*-i*a BLAW WAWBAR KhOS IBLACKI. . .

4-49 BLArih Df?AWBAi] KNOB IJVQRV)

4-'i0 BlAFW DflAWBAR UNfl^ <BRnWS>

, im-0141M

. (niJIW3M

, (131-0*4141

, Oil 014t4j

ai!-034Ul

0?>- 023110

[}flJ-UZ?020
ViD-iWlWOB

l3^-OtK>02J
17^-«UG01B
iJ-i-CHMWiq
017-^70658
nJ^rOjSS'O

A-i*

StflTCrt TAB PEIWUS5I0N HARMPNlC

. T)?s-aLM^ai

A-J^

HWB vlWATO CHMtIb

rtu■^l^:*5^/

ib-2h

ttMOB - tb* BR^P*

. 011-lrl4Ml

*-i/

hNDB S ii3' . . .

, . [ni-ui4nj

4-/»

HNPB - a'

OJi'OTftni

1
6-8

FIGURE 5

MANUAL ASSEMBLY BREAKDOWN

5" i CRADLE SPfilfJG A«) BRiCKO ASSY , . , . 060-0^^09

5- 2 «£V CDKB ASS&fflLY CPRESriS) nS7-03i21b

V 1 KFV COMB AS5MELBT iPBESFTs; .... , , il^J^linn7

5- 4 KE* COMB ASSE^ffiLt (MANUAL HET ) , . . 05?-0?1:TS

^- ^ BRACKET Ate CHANNEL 4SS* 'SHARPS! OSJ-03^B12

S' f^ B(?ACHET A* CHANNEL ASSV IWTURALSJ 057-O5^tt3l

>- 7 BRACKET *ND CHANNEL ASS> i CANCEL > 057-O35fl35

^- a BRACKET AHa CHANNEL ASSY iSHAHP PRESETS! h , - , 0^7-O3sai4

V 9 BRACKET flwD CHANNEL ASSY (B PRESET*. . . . 0>7'OJ20lJ

S-IO BRACKET AMD CHANNEL AS5> JPWESETSl O^7-0l5g33

5-n DO-NSTDP FELT 04:/-<KM70l

5-1? «rY CHANNEL FELT

5-11 UPSTDP FELT ,
■i-K MANUAL rONTJfcCTS

5-15 HANLIAL ACTUATORS . _ - . . . -. .

S'lb BUSBAR RETAINED

5-1' PERCU^S30N 5WITCH (UNDER B PRESET!
5-IB WNUAL BUSBARS {RECTANGULARl . . .

5-i9 MANUAL BUSBARS ISauABE! 141'3/U"1
0-7O MANUAL BUSBARS ( SflUAflE ^ UlU/lft"!

5-21 WIRE PAWiL

5-2^ TEEMIT

5-23 BUSBAR LUBE

04 1^-0 J JIM
02fl-n3Ii,S?

Q2*-aJ5*5?
Q3C-U3]t47

Ois-ojeie?

6-9

set

WfiERr

INSERT A

FIGURE 6

PEDAL KEYBOARD ASSEMBLY

A'lOS, B-3. E-lOO* E-2D0» £-300. H-lOO - . - . . 1^3-000009

b- I SPECIAL LOCATOR NUT 99S-0OiilJ

fr- 1 WUNTIMG -SCflaj , i _ . . . ai6-lOJ7U

6- ^ GLIDE 032-02^^90

fi^ 3 Pm»L KEY (CI- Dl. El. Fl. Gl. Al» Bl . CZ»

D2i £2r f7, G2> A2- B2. C3> - . . - - 060-OlS^U

fa- A POkAL KEY (Ajl. AfZl 060-01)597

6- % PEDAL KEY <GJ Z» 06O-03«9[

6- 6 PEDAL ¥.rr <Ct 2. F9 2i 060-03^590

e- r rajAL KEY IM 21 060'035SaS

«- e c[ivEP -.-,, 0'0-ooojoi

6- B COVEH MOUMTING SCTEW- ftfll-OB203I

b- fi COVER MOUNTING SCREW MASMER 399-000413

6_ 9 HINGE SPRING MOLJNT[h« SCREW SB5-091534

6-10 HINGE SPRING ,,,.. 017-03S5flfi

6-n PtEYBOARTJ BASE O70-O0O25Q

6-13 SHORT PTVOT _ _ OtJ-021J92

B-it ftnriJM PIVOT 04i-o?i79i

6-lZ LDNfi PIVOT .^, 04l-02l?93

6-n PEI*L CKY fC7| II 060-OJ^593

6-U PETAL KEY (F# 11 O60-03559A

6-15 PEBAL KEY <DJ 1) 0&0-035i95

6-lb PtDAL KEY iCt IJ OM)-G3559b

B-17 BLAtK PEDAL CAPS 02S-00169B

6-17 BLACK PEQAL CAP MOUNTING 5CREW 827-10^514

6-ia SWITtM PIJSHER SPflING 012-001800

6-1^ SWITCH PU5HEJ5 SPRING SCflEW 879-071114

(,-lQ STRETCHER BW - - QJO-OOOSOl

6-70 UPSTOP 5P4CER 070-001742

6-21 GUIDE BUSHING ..---.-. ...,.- 017-034726

6-22 UPSTOP RAIL 070-000401

6-23 r*lT . . ^ , ^ . » »99-OOU31

6-74 LKKWASHtR 999-000732

6-25 WASHES 999-000095

6-26 PEDAL FELT <5 HOLE » - U42-001911

ffZy PEDAL FELT {7 HOLE) - 042-Q01914

6-27 PEDAL FELT <2 HOLE* 042-001914

6-Zfl PEDAL GUIDE PIN (OlJ> STYLE> 027-OO1703

6-28 PEDAL GUIDE PIN < NEW ROLL PiN) , - . 020-039810

6-29 PEDAL GUIDE BUSHING 017-034775

6-79 WOOD SCRCK 801-0915U

6-30 FELT FOOT , . _ OA2-001727

fr-ll SIDE GUIDE FELT 042-001721

6-12 PEI»L DOWN STOP FELT , 042-001720

6-10

, »^ .is '""'*

Wf^m

►tWL SWITCH Jk&^EMBLT . .

7- I

PfDAt BUSBAR SHIFTEP

T^ 3

PED*L PUSHEfi PINS ( ^^ USED t

I- i

PED*L PUSHER FELT aNCLOSED

FIGURE

1 ih^aiitiooi^

oUTl-<j i'^<4U^

'- ^ BUSfl*BS f-NCLO^O/f

'i?'*-ijj|j^*i;^

JWM-"-'IVl/

mtAL L0NTACT5 lENCLOSOll

Wi-ftMi w

<>i/-D III '*;

" TELT iTflI&

iii^-fiOl*! J

50 48 19 12 55 >3 53 52 27 59

6^11

H- I

H- 1
S- i

a- ^

ft- b

a- J

B- a

ft- s

8-n

S-lfi

6-16
B-17

e-ia

9-15

a- 2?

B-2fi
fl-Z5
fl-26
S-27

a- 2a
a-2^
a- 10
a-11
a-iz

B-J3

ft-ic
a-i^
a-:]b

a-1/
a-jfl

a- 40

a-'-^

«lEAHPLlFr£B 4S5trtBL* .

CEBAMEC C4P fl-7K nt ^OOV

PE&tSTon 1 MTG.

RESISTOR lUOH

RESISTOR 390 K

REsrsTOR 22*^ VH

PCSISTOR 2.7H IW

WtSISTDR &20 OMtC

flESTSTOP too OHMS

RESISTDR 6flH

RESISTOR 330lt

RESISTOR 15 «£S

RESISTOR ?70K

RESISTOR *./K

RESISTOR WlRtVOJND 900 0*1'^ IQW
CERAMIC CAP B2 P* 500V ....

EEPAHIC CAP IK n' 500V . -
CEJIAMIC CAP 20* d' 500V . .
CAPACITOR 0,33 MF 400V . -
CERAMIC CAP 0.01 HF MOV ,
RESISTOR HJREWDurC 4,^K lOW
NESlSTOn WiRDfOUND T.5M LW
CFPAHIC CAP 220 Pt 500V

CERAMIC CAP 2.2K 0* 500V

RESISTOR 4T0K - -
RESISTOR 2,2 HEG -
RESISTOR ID fC6 5«

RESISTOR a20K

CERAMIC CAP 39 D' 500V

HE535TDR 1.8 «S

RESISTOR 4.7 FCG

HESiSTDR 2.7K IW

RESISTOR 100 3H*6

RE5ISTQR 2.7 HES

- ' 1 . h

-■ ■ '

RESISTOR i70 «

fitSlSTOR HJ MEfi

CAPACITOR O.OAT MF 400 V

Ll7-LI(>0lM'i
h«n-nJ0q7|

'jOu-iiri [ 1 1
hng-f p iita 1 1

liJO-OlOh'jl

(TUO-tj;093J

AQ0-n2l4bO

600-0206^1
blM-U?042l
hJ^-Ol023Z
i2^-OlOS01
i2SOl07b|
t01-030(>*J

hOi-070'01

A04-o;oa4i

^J^-OIOIJ]
^2^-010^81
b&0-02ini
haO-07U9J
6(KI-0JI452
ftO0'U21l9|
ft21-01OiU
&O0-un271
hl)0-02] ITl
600-QJOi^l

hoo-u^am
aori-D2i]U
&iju-az;i32

i0>-ai0453

VABMBLE POT (PERCUSSION CUTDFFI »K fcTh-HUOlJfc

VARIABLE PDT ( TONE I XlOK . 67&-O0O]ifi

CAPACITOR 1 MF 200V , . . . , 401-a?0?n

ELECT. CAP iOOOViSV CM)-O^QDa?

CAPACITOR 0.33 HF 200V ■ ■ fiOL-OJCIftW

CEHAHIC CAP 160 o' SOQV ■ - - - -

RESISTOR 1.2*C

l4-fi7

a-ftg
a-sn

a'6i

a-b2
fl-63

a-b'i

fl-6B

fr-h9

fl-Jii
fl-7»

a- 7 J

a-n
*-n
a-7^

CERAMIC CAP JVO of 5O0V --_..--- ^ ,. . ^25-01019?

CERAMIC CAP 3.311 pI 500V - - . . ft2^<liDtJl

CIHAHIC CAP 1,S>1 Df SOOV 4J'j-0l05fc2

RESISTOR l.SK ■ b"0-02O&3l

CnJAMlC CAP 150 of 5CI0V ft^^-lUD?1?

CEHAKIC CAP 30 &r 5O0V . - - I|?^-0l0l2l

CERAMIC UP 50 ftf ^OOV .,------.. 4?VUlOLai

RESISTOR 2.2R . hOn-OJESn

HESl&IQR 22K itUO-OJOfiH

RESISTOR ?a Dm5 6(io-fl2ongi

RESISTOR 62H ' MK}-OJO^^I

RESISTOR 2.2K iw .,..,.. bO0-llWlS7|

tueCT. CAP <4OM50. 40/400-30/350* -,..-.. i*h0-0fiO20O

CUCT, CAP ilD/310. 50y230< 30/14. 30H.9> - f,5O-OJ0l00

POWER TWANSFDRMER t1-7l I230V'50HZJ ODl-0167'il

POWER TRA«SFORHEP n li (113V/tOH21. ■ 0<l3-f>24fl»|

PERCUSSION OUTPUT WANSOrRHCfl (T-frl IKJI-Ojtin

OUTPUT TRA^FORMEW fT-3J nni-07&H9S

PEPEUSSiON INPUT TRANSFORMER fT-4J .---.--- l>03-lHftZ2*

PERCUSSJOU mTCHlNG TnANSFOftMEP ll-5V lH^3-Oife49')

CfftAMlC CAP 2A P* 500V - - - - 425-010101

SWELL CAPACnOR ASST. - - - . . . . OtiO-OJiftSJ

COVER SHORT OM-D^ZUJft

LOVER LONG ' ' . . - DM^0.20^B

AC TEPMIh^AL PA^EL «>6-O?3..0

TERHIKAL PAhEL ILONGI - - , . , , n^l-n220?d

TEPMINAL PANE-L 15H0RTP ■ 04I-0J2O76

6 - 4 TUBE 002-066201

TUBE SDCKETT - - W-IJllUn

1ZBH7 TUBE \}\M-t^\2\tM
TUBE SOCKET .OO*-O:i609

IZAKT TUBE - . (mJ-lTU*tni

TUBE WICRET ona-n-'jj*:

6AUh TUBE uy3H>0'j'iOO

lUBE SarKtT . . . . tlf>l-'(4UM

12AU7 TUBE O0?-0|?.ifK>

TUBE SOCKET , . . . UOS-(j;iMN

faC4 TUBE . flO?-0OhJOfl

TUBE SOCKET . OO^-onoJi

TUBE SHIELD .... , ULB-IU^UAJ

TUBE SHIELD .... . - iH0-0?JOaJ

eoo-oio-iii

6-12

FIGURE 9

PRESET P4NEL ASSEMBLY IJJ^OOOOOl

t -1 KftHKER PLATE - ^ 0ifl'0J6O^O

* -2 HAPKER PLATE Qja-DJ^O^O

9 -J BUSbAflS , 029-n3bOS?

^i BUSBAH . , OlS'QlbOSl

5 -S aUSBAB LH5UL>T0P 1 ROD ASSO^BLV 06?-0:t36i

9 -6 LQCHVlflE ...... . 01i-OJU7t

9 -7 SCREW (4 USO) , . . fl1*-O70flU

fl -a SCREW (85 bSEDl flft7-t>0000l

9 -^ LOCKWlHt OU-OJ1J43

VIBRATO LINE ASSEMBLV lil-000083

10- I CAPACITOR 0.005*/100V » - 406-OlOI^J

10-2 CAPACJTOR 0.010/lOOV iOft-DlOOJ?

10 3 CAPACITOR .OO^T/IOOV i-0fc-0l0?32

10 -i HESISTOH 22K ' - - fcOO-OSOBll

10 ^5 RESISTQH IHK

600-020791

10-6 COIL lEARLV MODELS^ < IB USED) - • » . 00 1-O169;4-O01

Ip -& COEL ILATO! HODELS J [ Ifl USEUJ 00J-0]3301

6-13

U-l START TO&&L£ SMITCrt -

li-J RUN iOG&L£ SWITCH ....

ll-l S>*11CH PLATE

(l_4 LAPPHOLDtP ASSEUHLT

\i -^ BAT HANDLE I FOH 5TARI A RUN 5WlTCM>

I I f- LENS I lNDlD»''Oft t-lCHTi

[It'i-lMhAll

I i'J BULB

I IS 5CHtWS -

I IN WASHER

II-Hj StROirt. PI *Tt

V>0

6-14

FIGURE 12

EXPRES51QN PEBAL *5StJfflLT ^ , l2]-(>aOOlO

13 - 1 RUBEEP hWT (BBOHH) . . . D*l-011t36

(BLACK) . . . Oi3-OlLl37

12-2 PEDAL SHAFT OM-02172S

I! - 3 BEARlUG aRACUrr ,,.-_, 025-031'kZ9

12 ' 4 WASHER - . . . _ q99'OaOfl85

IZ - 5 LOCKWASHEH 999-00073!^

OLD ST^LI LOCtfWASHEP * . - . 99y-Olim

12 - 6 SCREW eft6-!0O5l?

12 - 7 PQWL BEAfllKS <SLDTra> Ol7-03lfi31

IS - e DEAPING BRACKET 015-03U28

12-9 SCREW ^ . *35-D502ll

u-10 scno" flift-oaoiii

12-11 WASHEP 959-000729

12-12 WAS14EF 999-001121

12-13 SCREW 850-Ofl0^l2

n-li SflUAPE tJUT 999-001343

12-15 LOCKWASHEH 999-000729

12-16 SCREW aA3-08lll3

12-17 SCREW 83^-050211

IJ-m PELAi. AfOi 060-Q21?22

HARDWARE TOP ASST, FDP CONHECTlNG ROD

12-19 coNNEcTirve rod obD-021732

U-2C EXTENSION SPRIhJG 012-021365

12'?1 BRACKET 035-D21399

12-22 SCREW a^G'110914

l?-2J SCREW 616-09091'.

U-2ft NUT 999-001121

lJ-25 LDCKWASHEH -- - 999-000728

12-26 WASHER 999-000071

(2-27 SPACER 017-021427

HARDtUA^E FOR LOWER HOUMTIflO OF COWECTENG ROD

11-2& SCREW aifc-oao4n

17-29 LDCKWASMEP 999-000728

U-10 THRUSTVASHER ^ • - 999-OO0U9

13-31 SPflir^G-ASHfR 999-OOOlW

6-lS

TO C3
COKSOLE

FIGURE 13

PR-40 TONE CABINCT

tJ^

n- A RtVERBEPATinN A^^rMBLY

1 1- ^ 6A0t TJBE

n- h 6Ba5 TUEF

ii- ^ i?jiu?* njBf

IK a VAJ17 TUBE

II- « IZBHT* TIfM

iiu-iiJi?rn
i; I (iiiiuiH'i

lllf.f-IH>6'>tlli

04"?-^ U ion

iKU'H^I / kill

^lf^■-iM J«i/

l-H ELECT. CAPACITOR f40M50f 40/450. 30/3501 , - . 4W-OiD2aO

i-\: ^LWGE TUBE - . , . . 002-005301

I- I I PDVBER SUPPLV *SSV 1115V/60H7* ......... IJJ-OOOOlJ

"l-J J Paw:0 SUPPLT ASBT [230W50HZT 1^7-000015

M-t RECEPTACLE CONNECTOB - OO^-OliUl

1-1^ CONSOLE TO TONE CABIWT DVBLI ICDHPLETEJ .... Oll-O^MOa

i-\*- BULK CJkBLE DHLV [SPECIFY lENG™i - ^ ?00-00002J

t-|J CDNNtCTDR DNL^ ICONSQLE ENDJ - OOS-OlbOLH

V IB CONNECTOR ONLY (TONE CiBlMFT TUl * OOS-OnUl

*-l^ CONWCTOR C*PS c* ftEBUlRO) 06B'0J0^aO

^' ^ AC TO CONSQLt CABLE Oll-nJ5752

FIGURE 14

POUER SUPPtT ASSErtBLT . . , . , 137-OTUnn

It.' 1 PO^lESt TBANSFOfiMER i 113 VtJLT/60HZi 003-025*1?

14- I POMEP TRANSFORMER 1230 V0LT/5OHZJ OO^-OiftHS^

14- 2 FILTER CHOKE ...,_...,.,_..... OOl-OJ^ft^^

J^- i HESl^TW. tflRC WaUND bK> U>W M>&-Of{>77]

Ifc- t> ELECT. CfcPACiTOR bO/45G ft^O-'JIOtJ/L

In- > TEP^-IML PA^iFl COVER

JCl- 'i 5U4 n>Bf

Ift- 7 FEMALE CQhWECTQft

|jh- H e PEN M4UE PLUG

00/-W5J01

6-17

POWER *HPLIFIER ASSEMBLV ,.,._.. 1 56-nDi30lE>

15- I CAPiClTD'^ ID.DOQ of 42^-OLQ7^Z

15- 2 CAPACITOR FILM 0.a2/4O0V 401-030612

15- 1 RESISTOR 2T0 OHM ?• ^ 602-O5007Z

n- t RE51STBP 130 OHH 3W 607-05004;^

i5- 5 PFSlSTOfl ICO 0* 5W 6O3-06OIO1

15- h RESISTOR 22K - - hOO-020911

IS- 7 RESISTOR lOOK IW 6O0-0JO971

15- e flESlSTOR 250 OHH 3W 602-050061

15- 9 RESISTOR 15K - - - 600-020771

iS-rU RESiSTOP 5,6K »W bOO-030671

15-tl RESISTOR I20H IW 600-OJ0951

15-12 CEfl*HIC CAP 20.000 p( 62^-010763

15-13 RESISTOR 3.3 hCG - 600-021311

LS-14 CERAMIC CAP ICO Pt ftJ5-0l0?^2

15-li CEflArtlt CAP 150JJ 600-021011

15-16 CERA«IC CAP *,7K . - 600-020651

15-17 CERAMIC CAP 4?K 600-020^91

15-lfl CFTWMIC CAP 270H , 600-021071

15-19 RESISTOR taK IW 600-030931

15-20 CAPACITOR. CERAMIC- £200"t ...--......, 425-010^*2

15-21 CAPACITOR FUJI .0*0^200V ..... 401-020262

15-22 RESISTOR baOK 600-021171

15-33 CAPACITOR F]LH 0. I0/2OOV 401-020533

15-24 RFISISTOR IBOK 6OO-0JI031

15-25 RESISTOR 33K 600-070331

15-26 RESISTOR e20K 6DO-02U91

15-;J HESISTDR e2K 600-020951

1S-2H Ei£CT. CAP 3/50V 40?-oaooi7

15-29 ELECT. CAP 1 0K 600-020731

15-30 EL£CT, CAP 330K 600-C2JD91

15-31 ELECT. CAP 560K 600-021151

15-32 RESISTOR 2.7 MEG 600-021311

15-33 CEHAHIC CAP 2200 Pt 425-0105B2

l&-3fl CERAMIC CAP 1500 of - 4J5-0I0542

15-35 CZH^IZ CAP 1200 at 425-010522

15-36 CERAMIC CAP 4700 of 425-010662

15-37 CAPACITOR fUtH FILM IMFyiCX>V ..-..,.... 420-010113

15-3a CAPACITOR 2£0K 600-021051

15-39 CAPACITOR FILH O.UIDOV --,,--.,.-.,*. 406-010142

15-40 CAPACITOR FlLH ,aO47/100V 406-010042

15-41 RESISTOR 1.2 K£G 600-021211

lS-4? RESISTOR 6BK . ^. , . . . 600-020931

15-43 ELECT. CAP TD0/3V 407-010079

15-44 CAPACITOR FILM 4700 Pf 413-O1O042

15-45 PESLSTDR TflK 600-020791

15-46 RESISTOR 270 OHMS ^ 600-020151

15-47 RESISTOR 33K * » 6O0-O20a51

15-iiti TRfcNSlSTOft , OOl-OilOJQ

15-4fl ELECT. CAP UD0725< 100^25. 25^2^* 25/25> 450-040303

15-50 ELECT. CAP 3.3K 600-020611

15-51 ELECT 560 QH^^ ................. 600-030431

15-53 RESISTOR VARIABLE IK 676-000107

15-53 WtSISTOR 1£>K IW 600-030711

1^54 CAPACITOR FILM lO-OCO Ot 413-010142

\%-%% CERA^lIC CAP I'OOO Pt 435-010503

15-56 CERAMIC CA^ 4/0 of . . , . . . , ^ 425-010412

15-57 CERAMIC CAP 22QO oJ . 425-030533

15-56 CEPAMIC CAP 150 Pt 425-010^9?

15-59 CDIAHK CAP 100 P* 425-01025]

15-60 CAP AND HESISTOR PANEL ASST 063-O364O2

15-61 C*P ATC RESISTOR PANEL ASSY O6J-0235O6

15-62 CAP AND RESISTOR PANEL ASSY. . t D6>023513

15-63 RrVEHB EPIVE TRANSFORMER T4 OO3-025]27

15-64 7T>I3L£ OUTPUT TTJANSFORMER Tl . . . ^ , , . , » 003-023349

15-65 BASS OUTPUT TRANSroHMEP T2 003-0253i6

15-66 TT^LBLE OUTPUT TRAriSFOflfrCR tJ - h . . 003-035349

1^67 POTENTIOMrTER , . ^ ^ y . . . 676-O0O1O7

15-68 POT CONTROL KNOB , . . . O?5-0^?607

15-69 treble: reverb SWITCH . 0OB-03639B

15-70 BASS WEVEflB SWITCH OOS'023470

15-71 PDDH SIZE SWITCH O08-O23'.72

J5-7? TERMINAL PANEL . 006-023756

1^33 POST , 044*011434

»5-74 TERM[NAL COVER 0^1-038569

15-T3 T£ffH[NAL t'jfch^L , 006-022725

n^76 FILTER CAPACITOR - 430-040401

li-7? 12BN7A TUBE ..... ..,»..,.....,. . 002-012302

15-7fl TUBE SOCKET 004-031609

i5-7e 6Bfl6 TUBE 002-006700

15-78 TUBE SOCKET ^ 0O4-0316G9

15-79 12AU7A TUBE . . . - . ^ 002-012300

15-79 TUBE SOCHET t - - . . . ^ 0O'*-O2l609

15-80 b*iJ6 TUBE . - - - - - . ' 002-006500

15-80 TUBF SOCKET ■■ 004-021013

]5-Bl 12AX7 TUBE 002-012301

IS-RI TUB£ SOCKET 004-031609

6-19

LEVELING TABS

DRIVER

TWI5TED PAIR
'DRIVER" INPUT

SHIELDED LEAD
PICK UP" OUTPUT

SPRING "0" ^

LOCKING CAM

LIMI T CHANNEL

"'T' 6

LIMIT CHANNEL
CLIP

FIGURE 16

tl 1 tv

-1

REVtPBEPfiTrON UNTT ASSEHBLV - . - iJI-lHUIflMS

l*.' * SUSPENSION SPRIHG . - . Ot J-fl/ih-ift

Ih- ^ P[CK UP C&ll flS^thffiLV ...... . (J<li-fl,M?li.

('»' I WlVtFJ COIL A5SEMBLV , . Wt-l>l*.JH

I'l- . LJMM CHANhEL - - Oftl-O^J-jAl

(h- . LIMIT CHANNtt CLIP . , , . . . . . . , OlJ-OrilSJ*

Hi' 11 SPRTNG 1 tLDNGI

|hL.

SPftiNG 2 (MEUllM)

ift- s 5PRT»4G 3 iswami

FIGURE 17

1 7-

1 ^-

1 /-

1 7-

17-

l?^

I 7-

!T*

tl-

1 7—

C-3 CASE ASSEMELT . . |||-nooDU»

STATID^WPT Tap ■ - , - i . . - , [)1Q-tMS0bl

MOVEABLE TOP ft5SD1BLT U'lO-Qltifill

FALLBDARD ASSEMBLY • . • . <nO-Q16flJ]

HINGES fl XJBUii ' 0U-O;i'^H6

HINGES U USEJl . OlJ-OJl^Tfl

MUSIC PANEL - - - T ■ , - 0W-OJH2«9

MUSIC PANEL BASE - . . . . ^ ■ . . . . ll^fi-finOy^^

BUKPEP - r i . , . 0aj-irtl/lS9

HUSJC PANEL HENGER - ^ ^ . .... OlV-Qntaft0

njsic PANEL H[wE scPEws e£ii-nnj[*u

1 T n

'1 J

1 W J

-I?

Lid

-u

L ■ '

-U

1 7-

-U

■14

1 1 q

■ J%

JT-

■ H'

CATCH PLATt , - - - i i 032-015777

BACK PANEL ,--,^ 0W-OOO910

BENCH - . li:2'O0O0Hl

LOCK >(£T iOLD> , . ^ , , 03J-OOJBi,9

LOCH KEV (LAIFI » , * . 032-01626*

LOCK KEV <HOST F»eCE»tfI» OJ2-OA7W1

LOCK ASSEMBLE [FLUSH) .---.,.....,... O3J-016Jb7

PEDAL CLjIVIEP A5SY. f FOR PAOT^ SEE - i ,,,.._ . l^J-aOOOOl

ASSV. B^tJ^KHOWN)

6-21

27 (TYPICAL 38 PLACES)

2?. 20

(TYPICAL 4 PLACES!

FIGURE 18

CONSOLE REAR VIEW - C-3

in- I

I**- I

Ift- -■

IH- }

(H- -

IH- %

|*<- h

Ifl- '

IK H

1A' '*

1*1- n
rfl'ij

1A-I \

i;i- IS

PREAHPLiriCP A&yi i::J'IV/^h7<

OLi RISE *55Y '1 01JNL1 i

nUlUHF llBHTtWi

lAHPi IfCANDESCrWT ■ 1?0V/ ftO-'T*

TUBE WIBIHG

MAT truBBFR - '

SWELL PEDAL ASSfMElT

TflUMBSCPrw ^ruP RlflR PflNtLi

BHOULDFflO NUT

WT PLAIN b J2 I ^'ti4

CflNNrcTDO ftoa iS^f^fflLT

SVNCrtfEOI^OUS r«TOR 4 ^CANHEn <12av/bOH;>

^VNTHBONDU^ HOTW i SLANhER iJjnV/^OHj)

COVE» LINF P*hCL

LINE PAr^L ASStMBLV

Sf«|h*&, HFLICAL tJlTltdSlOhJ

II' Ml HI
I I ipiJMtHN

• ■ ■i."'."ftn'

|k4 Ir 11^ LJ> I
III •' .
y 4iiif I ' '" ■
. \ • \. A \>

B-

^CRn« EVE

I ' ,"11

^ .' I -»iniia I

^Ji-^i\^^tUhtl

W-IH SWeiL CAPACMOR ASSt

tft-(0 ::DHNFi:T[lfl fltCTOlCAL HfCEPTACLE

lA .*U ^PfllN&< 'ieLT[:AL EKlEM^lOh

I*-. SLEtVe & WASMffl ASST, (GEWHAIOR

!« 'F. "WTCrtlNG raANSJOHrttW *SS* .

10- ,V

C0KT4C1 tLECnsjCAL
5CRtW *G(Hn!ATUft MUlJWTT

BUN no^'' ,iiovv*art^)

STA&T MOTOR 'liav/hOHl:
PtXAL FiLiLfl . .

ll^'V. PEDAL TflANSFrJftftfl

|»>>-0I1J."«

1]'-TJ-0.'| J>(

. i**** I*.') \nn

. . OUJ-OtKi 11)11

mm-uJU7M

. p.-i-lirXlllf»l

. . nji-Djsrvu
on 1-0^)1 M

TABLE OF CONTENTS - B
EARLY HAMMOND CONSOLES

MAJOR ASSEMBLY

FRONT & REAR VIEWS OF MODEL RT3

PAGE

6-24

MATCHING TRANSFORMER

6-27

REAR VIEWS OF MODEL AlOO & DlOO 6-25

REAR VIEW OF MODELS WITH TREMULANT 6-26

REAR VIEW OF MODELS WITH VIBRATO 6-26

QtONEBAR ASSEMBLY 6-27

(T) UPPER AND LOWER KEYBOARD ASSEMBLY 6-27

(T^ PEDAL SOLO END BLOCK 6-27

(ZT) PEDAL KEYBOARD ASSEMBLY 6-27

PRESET PANEL 6-27

GENERATOR

6-27

PREAMPLIFIER , 6-28

PEDAL SWITCH ASSEMBLY 6-28

AMPLIFIERS 6-28

REVERB AMPLIFIER 6-29

REVERB UNIT ' 6-29

POWER SUPPLY 6-29

SPEAKERS 6-29

5J PEDAL SOLO GENERATOR 6-30

PEDAL SOLO TUNER 6-30

VIBRATO LINE BOX 6-30

is) VOLUME CONTROL ASSEMBLY (RHEOSTAT BOX) 6-30

EXPRESSION PEDAL 6-30

6-23

CONCERT MODELS RT, RT-2, AND RT-3

HLAI^ VIKW ni- JLl - ^ IWiJJi i'MUUSSlONJ.

6-24

tDAL SwriCH
EfJCLOSEDl

REAR VIEW HODET_ A-IOO

REAR VIEW MODEL U-lUU

6-25

JVriU-M Jif-AJ< VIK'A Uk' i.tiNSl.'l Es \t 11 H I Kl XlLU , \^'l ,

lYPlC^Ai, UKAM V|l A U^ c:nNNni tS \Vini Vll^KAlO-

6-26

TONEBAR ASSEMBLY

1. TOHEBAR KNOBS BLACK 025-035570

IVORY 025-035571

BROWN 025-035572

NOTE: PARTS FOR EARLY "RATCHET" -

"CLICK" TYPE TONEBAR ASSEMBLY
ARE NO LONGER AVAILABLE. FOR
PART # INFORMATION ON LATER
SERIES TONEBAR ASSEMBLY, SEE
PAGE 6-7 OF B-3/C-3 PARTS LIST.

UPPER & LOWER KEYBOARD ASSEMBLY

1. VIBRATO-CHORUS SWITCH MODEL BV.CV ,RT. .. .008-0 16988

2. FRONT STRIP ASSEMBLY (LOWER)

MODEL RT,D100 061-035813

NOTE: MOST PARTS ARE SIMILAR TO PARTS
USED IN THE UKB & LKB OF THE
MODEL B-3 OR C-3. FOR PART #
INFORMATION, SEE PAGES 6-8 AND
6-9 OF THE B-3/C-3 PARTS LIST.

PEDAL SOLO ENDBLOCK

1. POTENTIOMETER (VOLUME) 500 OHM 676-000221

2. OUTPUT TRANSFORMER 003-025348

PEDAL KEYBOARD ASSEMBLY (32 PEDAL)

1. PEDAL CAPS (BLACK) 025-002664

2. SWITCH PUSHER SPRING (LONG) 012-035754

(SHORT)

3. WHITE PEDAL ASSEMBLY (ALL EXCEPT Lo C,

D,Hi E,F,G) 050-035756

4. DOWNSTOP FELT (4 HOLE) 2 USED

(6 HOLE) 6 USED 042-002666

(8 HOLE) 4 USED
(PARTS INFORMATION ON 25 PEDAL KEYBOARD
IS FOUND ON PAGE 6-10 OF B-3/C-3 PARTS LIST.)

MATCHING TRANSFORMER

MODEL AIOO, DlOO, RT3 003-022020

PRESET PANEL

(SEE PAGE 6-13 OF B-3/C-3 PARTS LIST.)

GENERATOR

1. FLYWHEEL COUPLING SPRING (2 USED) 012-002345

2. GEARS COUPLING SPRING 012-031463

3. COUPLING DRIVE SHAFT 064-035768

(SEE PAGES 6-6 AND 6-22 OF THE B-3/C-3

PARTS LIST FOR ADDITIONAL
INFORMATION.)

fa-27

PREAMPLIFIER

NOTE: PARTS INFORMATION FOR THE PREAMPLIFIER

USED ON MODELS AlOO, DlOO AND RT3 IS

FOUND ON PAGES 6-11 AND 6-12 OF THE B-3/C-3

PARTS LIST.

1. VIBRATO LINE TRANSFORMER MODEL BV,CV,RT 003-016906-001

2. VIBRATO OUTPUT TRANSFORMER BV,CV,RT 003-016906-002

3. HEATER TRANSFORMER

MODEL BV,CV,RT 003-016 90 7-001

MODEL E 003-017831-001

FOR 56-57 PREAMP

4. OUTPUT TRANSFORMER

MODEL E OR 56-57 PREAMP 003-017826

MODEL AV,BV,BCV,CV,DV,RT 00 3-016906-00 2

MODEL R2,C2,RT2 003-024895

5. POWER TRANSFORMER MODEL B2,C2,RT2 003-021414-001

6. POTENTIOMETERS (TONE CONTROL)
MODEL A,B,C,D,G,BV,CV,RT IMEG

MODEL E DUAL lOOK

MODEL B2 ,C2 ,RT2 300K 676-000126

7. VACUUM TUBES #5 6

#57

6SJ7 002-006502

6SN7 002-006306

6SC7 002-006305

6J7 T000-00000 0-6J7

6J5

8. SWELL LEVER & BUSHING ASSEMBLY
MODEL A100,D100,RT3 060-029990

B2,C2,RT2 060-021406

9. TRIMMER CAP (ALL) 499-021468

PEDAL SWITCH ASSEMBLY (32PEDAL)
MODELS DlOO AND RT SERIES

1. PEDAL SIGNAL CONTACTS 012-033530

2. BUSBAR CONTACTS

3. PUSHER PINS 017-001746

4. ACTUATORS

5. PEDAL FELT STRIP 042-030749

(INFORMATION ON (25 PEDAL) PEDAL SWITCH

ASSEMBLY IS FOUND ON PAGE 6-11).

;i0J AMPLIFIERS

MODEL A-lOO (AO-39)
MODEL D-lOO (AO-33-5)

1. POWER TRANSFORMER AO-39

DOMESTIC I20V/60CY
EXPORT 234V/50-60CY 003-036754

2. OUTPUT TRANSFORMER

AO-39 003-024897

AO-33-5 TREBLE T1,T3 003-025349

BASS T2 003-025346

3. FILTER CAPACITOR

AO-39 DUAL 30MFD/450V

AO-33-5 40/40/30MFD/450V 450-040200

6-28

4. ROOM SIZE SWITCH AO-33-5

5. POTENTIOMETER AO-33-5 (REV GAIN) 2K. . .676-000107

AO-39 (HUM BALANCE) 100 OHM
AO-39 (SIGNAL BALANCE) 250 OHM

6. AC PLUG (2 PRONG) AO-39

7. 5 PIN RECEPTACLE AO-39 005-020790

8. 4 PIN RECEPTACLE AO-39 005-020864

9. VACUUM TUBES 12AX7/ECC83 002-012301

6BQ5 002-006700

5U4/5Y3 002-005201

12AU7 002-012300

12BH7 002-012302

10. TRANSISTOR AO 33-5 001-021070

REVERB AMPLIFIER

MODEL AlOO (AO-35) (EARLY SERIES) 126-000111-007

(AO-44) (LATER SERIES)

1. POWER TRANSFORMER

AO-35

AO-44 DOMESTIC I20V/60CY 003-024956

EXPORT 220V/50CY 003-036756

2. OUTPUT TRANSFORMER AO-35

AO-44 003-036552

3. FILTER CAPACITOR AO-35 450-040200

AO-44

4. MINIATURE LAMP GE ifll 6.3V/. 15A 016-022885

5. LAMP HOLDER

6. POTENTIOMETER AO-44 R27 2K

7. TRANSISTOR AO-44 001-021260

8. FUSE AO-44 ONLY DOMESTIC 3/4A 016-039512

EXPORT 3/8 A

9. VACUUM TUBES 5U4/5Y3 002-005201

ECC83/12AX7 002-012301

6BQ5 002-006700

EZ81/6CA4 002-006200

ECL86/6GW8 002-006401

REVERB UNIT MODEL AlOO & DlOO 121-000046

POWER
NOTE:

SUPPLY MODEL DlOO
THE POWER SUPPLY OF THE DLOO IS
SIMILAR TO THE POWER SUPPLY USED
ON THE MODEL PR-40 TONE CABINET.
FOR PART # INFORMATION, REFER TO
PAGE 6-17 OF THE B-3/C-3 PARTS
LIST.

SPEAKERS

MODEL AlOO REVERB 12"

8 OHM.. .

...014-024676

ORGAN 12" 8 OHM (2

USED)

014-023232

MODEL DlOO REVERB & TREBLE 8"

8 OHM

014-025397

BASS 12" 8 OHM (2

USED)...

...014-021270

6-29

5 J PEDAL SOLO GENERATOR

DlOO

RT SERIES 114-000002

1. FOi.'ER TRANSFORMER Tl

2. AUDIO TRANSFORMER T2

3. FILTER CAPACITOR 40/20/20MFD/400V 450-040200

20MFD/400V

4. MULTI CONNECTOR (FEMALE) 005-019113

5. MULTI CONNECTOR (MALE) 005-019081

6. TUBE SOCKET (L3 USED) 004-018934

7. VACUUM TUBES 6J5

6SL7 TOOO-000006-SL7

6SN7 002-006306

6SC7 002-006305

(fe) PEDAL SOLO TUNER ASSEMBLY MODEL DlOO & RT
NOTE: PARTS FOR PEDAL TUNER ARE NO
LONGER AVAILABLE.

^t) VIBRATO LINE BOX

MODEL BV,CV,RT

B2,C2,RT2 121-021860-001

AiOO,D100,RT3 121-000083

1, COIL MODEL B2,C2,RT2 003-021842-003

EARLY MODEL ALOO,D100,RT3 003-016924-001

LATER MODEL AlOO ,D100 ,RT3 003-033303

8^ VOLUME CONTROL ASSEMBLY (RHEOSTAT BOX)

1 CAM RHEOSTAT 045-002013

(19) EXPRESSION PEDAL

MODEL B2,RT2 123-000009

MODEL C2,A100,D100,RT3 123-000010

(FOR ADDITIONAL INFORMATION, SEE PAGE
6-15 OF B-3/C-3 PARTS LIST.)

6-30

TABLE OF CONTENTS - C
EARLY HAMMOND TONE CABINETS

MAJOR ASSEMBLY

PAGE

TONE CABINET CROSS REFERENCE 6-32

(T^ POWER AMPLIFIER 6-33

(2^ SPEAKERS 6_34

©TUBES 6-3A

(J?) REVERB AMPLIFIER (j_34

(6J CABLES AND CONNECTORS 6-35

NOTE; THE PART INFORMATION FOR TONE CABINETS IS BROKEN DOWN BY AMPLIFIER
TYPE. PLEASE REFER TO THE CROSS REFERENCE ON BACK OF THIS PAGE TO
DETERMINE THE AMPLIFIER TYPE BEFORE PROCEEDING.

6-31

b-32

TONE CABINET CROSS REFERENCE

MODEL

SERIAL /;

AMPLIFIER TYPE

A-20

1000 & ABOVE

A-40

2400 & ABOVE

B-40

2400 to 19 841 INCL

C-40

2400 & ABOVE

D-20

4348 to 25109 INCL.
25110 to 26968 INCL
26969 & ABOVE

F
G

H-l-A

DR-20

15007 to 22399 INCL

22400 to 35303
35304 & ABOVE

F
G

HR-1

DX-20

ALL

ER-20

27001 to 28709

F-40

37001 to 37659
37660 & ABOVE

G
H-l-A

FR-40

35001 to 35623 INCL
35425 & ABOVE
35624 & ABOVE

C
HR-1
H-l-A

ALL

H-40

HR-40

JR-20

55002 to 59999
50002 to 59999
6000 & ABOVE
60660 & ABOVE

55002 to 56499
50002 to 56499
56500 & ABOVE
80061 & ABOVE

30500 to 32015
32016 & ABOVE
75877 & ABOVE

INCL.
INCL.

JR
K
LR
LR CODE

"B"

INCL.
INCL.

LR CODE

"B"

AO-

AO-15

-15 CODE

"B"

AO-15 CODE "C"

P-40

ALL

AO-40

Q-40

ALL

AO-40

FOR PARTS INFORMATION ON THE MODELS PR40,

QR40 AND PR20 TONE CABINETS

, REFER TO PAGE

6-16 OF B-3/C-3 PARTS LIST.

(TJ) POWER AMPLIFIERS
^''^ TYPE "F"

POWER TRANSFORMER

AO-16670-1.

.003-016670-

-002

OUTPUT TRANSFORMER

AO- 16681-1

003-016681-

-001

FILTER CHOKE

AO-16682-1

TYPE "G"

POWER TRANSFORMER il5V/60Hz

115V/50-60HZ
230V/50l{z

AO-16670-5.

AO-16670-6
AO-16670-7

.003-016670-

-002

OUTPUT TRANSFORMER

AO-166S1-2

FILTER CHOKE LI ,L2 (40 OHM)

AO-16682-1

TYPE H-l-A

POWER TRANSFORMER 115V/60Hz

115V/50-60HZ
230V/50HZ

AO-20927-I.

AO-20927-2

AO-20927-3

.003-036899

OUTPUr TRANSFORMER

AO- 16681-4

FILTER CHOKE LI ,L4 (40 OHM)

AO-16682-2

TYPE HR-1

POWER TRANSFORMER lI5V/60Hz

115V/50-60HZ
230V/50-60HZ

AO-20927-1.

AO-20927-2
AO-20927-3

.003-036899

OUTPUT TRANSFORMER

AO- 16681-3.

.003-016681-

-003

FILTER CHOKES (40 OHM)

AO-L6682-2

REVERB TRANSFORMER

AO-16134-1

003-016134-

-003

TYPE JR

POWER TRANSFORMER L15V/60Hz

L15V/5O-60HZ
230V/50-60HZ

AO-20927-1.
AO-20927-2

AO-20927-3

.003-036899

OUTPUT TRANSFORMER

AO-16681-5

FILTER CHOKES (40 OHM)

AO-16682-2

REVERB TRANSFORMER

AO-16134-1.

.003-016134-

•003

TYPE K

POWER TRANSFORMER 115V/60Hz

115V/50-60HZ
230V/50-6OHZ

A020927-4
AO-20927-5

AO-20927-6

003-036899

OUTPUT TRANSFORMER

AO-21106-1

FILTER CHOKES (40 OHM)

AO-16682-2

TYPE LR

POWER TRANSFORMER 115V/60Hz

115V/50-60HZ
230V/50-60HZ

AO-20927-7,

AO-20927-8

AO-20927-9

.003-036899

OUTPUT TRANSFORMER (TREBLE)

AO-21264-0

(BASS)

AO-21106-3.

.003-021106-

■003

FILTER CHOKES 6 HENRY

18 HENRY

AO-2126a-0
AO-16682-3

REVERB TRANSFORMEb.

AO-16134-2.

.003-016134-

■003

6-33

TYPE AO-15

1. POWER TRANSFORMER lL5V/60Hz

115V/50-60HZ
230V/50-60HZ

2. OUTPUT TRANSFORMER (TREBLE)

(BASS)

3. FILTER CHOKES 2.5 HENRY

15 HENRY

4. REVERB TRANSFORMER
TYPE AO-40

1, POWER TRANSFORMER I15V/60Hz

115V/50-60H2

230V/50-60H2

2, OUTPUT TRANSFORMER (TREBLE)

(BASS)

3, FILTER CHOKES 6 HENRY

18 HENRY

AO-20927-10
AO-20927-11

AO-20927-12

AO-21566-L. ,003-021566-001

AO- 166 81-6 00 3-0166 81-006

AO-16682-5

AO-16682-4. .003-016682-004

AO- 16 134-3 003-0 16 L 34-003

AO-235L4-1. .003-023514-001

AO-23514-2

AO-23514-3

AO-21264

AO-21106-6

AO-21268-I

AO-16682-3

SPEAKERS

NOTE: ELECTRO DYNAMIC SPEAKERS ARE

NO LONGER AVAILABLE. USE PART it
014-021270 AS A REPLACEMENT
ALONG WITH 250 OHM 10 WATT
RESISTOR, FOR THE FIELD COIL.
SEE PAGE 6-36 FOR MORE DETAILS.
MODEL JR20,HR40,KR40,H40,K40

10" 6-8 OHM 014-021075

12" 8 OHM 014-021270

MODEL PR20 15" 4 OHM 014-028923

12" 8 OHM 014-021270

MODEL PR40,QR40,P40,040

15" 4 OHM 014-023421

12" 8 OHM 014-021270

TUBES #56

2A3

6J5

6V6 00 2-006 703

5U4 002-005201

6SN7 002-006306

6SC7 002-006305

6SJ7 002-006502

REVERB AMPLIFIER

(USED IN MODELS DR ,ER,FR,T0NE

1. OUTPUT TRANSFORMER

2. COUPLING TRANSFORMER

3. HEATER TRANSFORMER

4. TUBES

CABINETS)

AO-16134 003-016134

AO-16135
AO-16133-l

6J5

6J7 TOOO-O00000-6J7

6SN7 002-006306

6SJ7 002-006502

6-34

(TJ) PLUGS AND RECEPTACLES

1. 5 PIN PLUG 005-016018

2. 5 PIN RECEPTACLE 005-016032

3. 6 PIN PLUG 005-0L6156

4. 6 PIN RECEPTACLE (WAFER TYPE) 005-020757

5. 6 PIN CONNECTOR (WAFER TYPE) 005-020758

6. 7 PIN PLUG 005-016121

7. 7 PIN RECEPTACLE ■ 005-016126

(T) CABLES AND CONNECTORS

1. 5 CONDUCTOR CABLE COMPLETE 011-036408

2. BULK CABLE (5 CONDUCTOR)

(SPECIFY LENGTH) 200-000022

a. CONNECTOR (CONSOLE END) 005-016018

b. CONNECTOR (TONE CABINET END) 005-016032

c. CONNECTOR CAPS (4 USED) 060-020560

3. 6. CONDUCTOR CABLE (NOT SHIELDED)

30' 511-017277

50' 511-017277-050

100' 511-017277-100

4. BULK CABLE (6 CONDUCTOR)

(SPECIFY LENGTH) 511-010 29 8

a. CONNECTOR PLUG 505-061721

b. CONNECTOR SOCKET 504-029546
C. CONNECTOR CAP PACKAGE (2 USED) ... 505- 137457

5. AC LINE CORD

(CONSOLE TO WALL OUTLET) 011-035752

SPEAKER RLPLACEMENT IN £ARLY TONE CABINETS USING ELECTRODYNAMIC SPEAKERS

Electrodynamic speakers are no longer being manufactured. They can be replaced
with Permanent Magnet (PM) speakers in early Hammond tone cabinets. Good results
will be achieved^ if the instructions below are followed.

Order two speakers, or four speakers as related to tone cabinet > #014-021270.

1, Remove speaker plugs from amplifier and remove both speakers from tone cabi-
net.

2. Clip all A wires from both speakers as close to speaker as possible.
3« Discard both speakers.

4, Remove wires from pins 1 and 6 of the 6 pole plug. Remove these wires from
cable.

5. Remove wires from pins 1 and 5 of the 5 pole plug. Remove these wires from
cable.

6, Install a 250 ohm 20 watt resistor across pins 1 and 5 of the 5 pole plug.
Use sleeving over lead connected to pin 5.

7. Solder 2 remaining wires in each speaker cable to the new PM speakers. Sol*
der wire with solder lug to the left hand speaker terminal as viewed with the

speaker terminal strip facing up. Solder wire from speaker plug to right
hand tenninal.

8, Mount new speakers in cabinet and insert plugs into amplifier- Attach leads
with solder lug to upper binding post.

9. Dress 250 ohm resistor away from any speaker leads or other objects to assure
adequate heat dissipation.

CHASSIS

USE SLEEVING
ON THIS LEAD

6-36

HOOO-000495 11/87 5C printed in u.s.a.

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Full text of "Hammond Organ Service Manual - Early Models (A,B,C series, B3, A-100, RT, D, G, etc.)"

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