Hammond M Series User manual

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INGLUDINe
PARTS LIST
H000-006059
CAUTION
SEE SAFETY NOTICE ON
INSIDE COVER SHEET
ORGAN SERVICE COMPANY
6475 JOLIET ROAD SUITE B-t
LaGRANGE ILLINOIS 60525
PHONE [phone]

SAFETY NOTICE
Great care has bean taken In the design and manufacture of this product to assure that no
shock hazard exists on any exposed metal parts. Internal service operations can expose the
technician to hazardous line voltages and accidentally cause these voltages to appear on
exposed metal parts during repair or reassembly of product components. To prevent this, work
on these products should oniy be performed by those who are thoroughly familiar with the
precautions necessary when working on this type of equipment.
To protect the user, It Is required that all enclosure parts and safety Interlocks be rettored to
their original condition and the following tests be performed before returning the product to
the owner aftor any service operation.
Plug the AC iine cord directiy Into aline voltage AC receptacle (do not use an Isolation
transformer for this test) and turn the product on. Connect the network (as shown below) In
senes with all exposed metal parts and aKnown earth ground such as awater pipe or conduit.
Use an AC VOM of 5,000 ohms per volt or higher sensitivity to measure the voltage drop across
the network. Move the network connection to each exposed metal part (metal chassis, screw
heads, knobs and control shafts, escutcheon, etc.) and measure the voltage drop across the
network. Reverse the line plug and repeat the measurements. Any reading of 4volts RMS or
more is excessive and indicates a potential shock hazard which must be corrected before
returning the product to the user.
n
TEST
PROBE
VOM
AC SCALE
IOK
I I
.01 Mf
CERAMIC RF
BYPASS CAP
TEST CLIPS
CONNECTEQ TO WQWN
EARTK ORQUHO
TO EXPOSED HETAL PARTS

TABLE OF CONTENTS
PAGE PAGE
GENERAL DESCRIPTION
INSTALLATION AND MAINTENANCE
MUSICAL TERMS
NOTES AND OCTAVES
HABMONICS OR OVERTONES
ONE KEY DOES NOT PLAY 19
ONE NOTE IS WEAX 20
PERCUSSION NOTES VEAK 2I
PEDAL NOTE SOUNDS AT FULL VOLUME 21
PEDAL NOTE SOUNDS FAINTLY 21
BOW THE ORGAN WORKS HUM 21
CONSTRUCTION AND OPERATION OF COMPONENTS 7
MOTORS AND POWER SWITCHES 7
TONE GENERATOR
MANUALS 8
HARMONIC DRAWBARS 9
PEDAL DRAWBAR 9
PEDAL KEYBOAIU) 9
EXPRESSION PEDAL 10
CONTROL TABLETS 10
PERCUSSION CONTROL TABS 10
VIBRATO TABS 11
+
PRESET TABS 12
REVERBERATION-VOLUME SOFT TABS ,,.12
AMPLIFIER ASSEMBLY 12
MANUAL SECTION OF AMPLIFIER 13
PEDAL SECTION OF AMPLIFIER I
A
INTERMEDIATE SECTION OF AMPLIFIER 15
OUTPUT SECTION OF AMPLIFIER ,.,. 15
PERCUSSION SECTION OF AMPLIFIER 16
POWER SUPPLY 17
TUBE SOCKET VOLTAGES H
REVERBERATION AMPLIFIER 17
SPECIAL EQUIPMENT 18
RADIO, PHONOGRAPH, OR MICROPHONE 18
EXTENSION SPEAKER 18
EAR PHONES IS
SPECIAL POV,^R SOURCES 19
PRACTICAL SERVICE SUGGESTIONS 19
ORGAN DOES NOT PLAY 19
REPLACING TUBES 22
PROCEDURE FOR REMOVING PARTS 22
UPPER MANUAL KEY 22
LOWER MANUAL KEY 22
DRAWBAR CONTACT SPRING 23
DRAWBAR OR DRAWBAR KNOB 23
UPPER MANUAL 24
LOWER MANUAL 25
CONTROL PANEL ACCESS 26
PERCUSSION SWITCH ACCESS 26
GENERATOR 26
STARTING MOTOR 26
PILOT LIGHT 26
TAB SWITCH 26A
VIBRATO LINE BOX 26A
PEDAL KEYBOARD 26A
EXPRESSION PEDAL 26A
PRESET PERCUSSION UNIT 77
SELECTOR SWITCH 78
HARMONIC BUSBAR SWITCHING &REIT- SPLIT 78
UPPER MANUAL 78
MODE SWITCH 79
FREQUENCY DIVIDER 79
CYMBAL AND BRUSH 80
BRUSH KEi'ING 80
.CYMBAL KEYING 80
CXMBAL-BRUSH AMPLIFIER AND NOISE GATE 80
CH.\NnES AM REVISIONS 81
IiKTALLr\TION AND MAINTENANCE BACK COVER
1

LIST OF FIGURES AND ILLUSTRATIONS
FIGURE PAGE
1
.
Front View of Console -Model M27
2. Front View of Console -Model M-2 28
3. Back View of Console -Model M, M-2 29
4. Front View of Console -Model M-3 30
5. Back View of Console -Model M-3 31
6. Front View of Console -Model M-lOO 32
7. Back View of Console -Model M-lOO 33
8. Block Diagram -Model M." 34
9
.
Block Diagram -Model M-2 34
10. ,Block Diagram -Mcdel M-3 35
11. Block Diagram -Model M-lOO 35
12. Typical Tone Generator 36
13. Magnet Locations on Tone Generator .,,. 36
14
.
Generator Cover -Model M37
14A. Generator Cover -Model M-Serial 15083 and Up 37
15. Generator Cover -Model M, M-2, M-3 38
16
.
Generator Cover -Model M-3 -90485 and above 39
17. Generator Cover -Model M-lOO 40
18. Manual Wiring Chart 41
19. Drawbar Assembly 42
20. Pedal Keyboard Assembly -M, M-2, M-3 42
21. Pedal Keyboard Assembly -M-lOO 43
22. Fundamental Vibrato System -M43
23. Vibrato System -Model M -13509 and below 44
24. Vibrato System -Model M-13509 and above 44
25. Fundamental Vibrato System -M-2, M-3 45

LIST OF FIGURES AND ILLUSTRATIONS CONTINUED
FIGURE PAGE
26. Fundamental Vibrato System -M-lOO 46
27. Vibrato Line Box-Model M, M-2 46
28. Vibrato Line Box -M-3 47
29. Vibrato Line Box -M-lOO 47
30. Vibrato Scanner 47
31. Vibrato System M-2 -Serial 19000 to 22253 48
32. Vibrato System M-2 -Serial 25254 and above 48
33. Manual Hold Down Screws (M, M-2, M-3) 49
34. Pictorial -Model MAmplifier 50
35. Pictorial -Model M Amp. -Serial 8411 and above 51
36. Pictorial -Model M-2 Amp. Serial 19000 and above 52
36A. Pictorial -Model M-3 Amp (Partial) 53
36B. Pictorial -Model M-3 Amp 54
37. Schematic AO-35 Reverberation Amp M-lOO 55
38. Schematic AO-44 Reverberation Amp M-lOO 56
38A. Schematic AO-44 -See Serial Numbers 57
39. Schematic AO-66 Reverberation Amp (Later Model M-lOO) 58
40. Schematic Model M 59
41. Wiring Diagram Model M60
41A. Wiring Diagram Model M-Serial 15083 and above 61
42. Schematic Model M-2 -19000 and above 62
43. Wiring Diagram Model M-2 -Serial 19000 and above 63
43A. Wiring Diagram Model M-2 -Serial 25254 and above 64
44. Schematic Model M-3 65
F
44A. Schematic Model M-3 Serial 90485 and above 66
44B. Schematic Model M-3 -Serial 109466 and above 67
45. Wiring Diagram Model M-3 68

LIST OF FIGURES AND ILLUSTRATIONS CONTINUED
FIGURE PAGE
45A. Wiring Diagrams Model M-3 -Serial 90485 and above 69
46. Schematic Model M-lOO with AO-35 and AO-29 70
47- Schematic Model M-lOO with AO-44 and AO-29 71
48. Schematic Model M-lOO with AO-66 and AO-67 72
49. Wiring Diagram M-lOO with AO-35 Amp 73
50
.
Wiring Diagram M-lOO with AO-44 Amp 74
51. Wiring Diagram M-lOO Control Panel ,73
i
M-IOOA SUPPLEMENT
52. M-IOOA Percussion Kit Wiring Diagram 82
53. Brush and Cymbal Wiring Diagram with AO-66 Amp 83
54. Brush and Cymbal Wiring Diagram with AO-44 Amp °^
55. Schematic -Percussion Preset Unit 85
56. Schematic Diagram Model M-IOOA 87
57
.
Wiring Diagram Model M-IOOA 88
58. Percussion Kit Circuit Board Component Layout 89
4

GENERAL DESCRIPTION
The Hammond Organ "m" Series Spinet Consoles are completely self contained, re-
quiring no external tone cabinet. All Models have two (2) manuals of forty-four
(44) keys each, a12 (M, M-2, M-3) or 13 (M-lOO) note pedal keyboard, and an ex-
pression (or swell) pedal for controlling the volume. All tones are produced
by electro-magnetic tone generators and electrically amplified. Selection of tone
colors is made by adjusting eighteen(18) drawbars, and other characteristics of
the music are adjusted by means of tilting control tablets and tab switches. A
push button and atoggle switch or two toggle switches located in the front of
the Console are used to turn on the organ.
Figures 1thru 7show the front and rear views of the "M" Series Models- The
rear views are shown with the dust covers removed. Console rear panels are an
optional accessory and are not shown.
INSTALLATION AND MAINTENANCE
Acard packed with the playing instructions or located in the bench gives full in-
formation on installing the organ, oiling, and packing for moving or shipment.
(See Back Cover) MUSICAL TERMS
The service man who has had no musical training will find the following infor-
mation helpful in studying the operation of the organ.
NOTES AND OCTAVES
Keyboard instruments are divided into '^octaves" of 12 keys or notes, each with
spven (7) ''naturals" (white keys) and five (5) "sharps" or "flats" (black keys)
in adefinite sequence. Black keys occur in groups of two and three in each
octave and offer aconvenient way to identify the notes of the octave. Techni-
cally there is no difference between ablack key and awhite one, since each key
has afrequency 1.059 times the frequency of the next one below it.
Each note has afrequency exactly one half that of the corresponding note in the
next higher octave. Each white key is called by aletter for Ato G and these
letters are known as "note of the musical scale", A black key may be called a
"sharp"of the notes below it or a'^flat" of the notes above it; for instance, the
black key between Cand Dmay properly be called Cif (Sharp) or D*^ (D flat).
HARMONICS OR OVERTONES
Any musical note has adefinite fundamental pitch or frequency and also acertain
"tone quality" or "timbre" depending on its wave shape. Acomplex note is one
which includes not only afundamental frequency but also one or more "harmonics"
or "overtones," each of which is an integral multiple of the fundamental frequency.
Such acombination is more pleasing musically than anote having only asingle
frequency. The ear does not distinguish the harmonics independently ,but instead
identifies the note as acomplex tone having the pitch of the lowest component, .
or fundamental
.
HOW THE ORGAN WORKS
Most tone sources, such as strings, reeds ,or pipes, produce complex tones .The
Hammond tone producing mechanism, however, generates individual frequencies which
can be combined by means of harmonic drawbars to produce any desired tone quality.
The block diagrams in Figures 8thru 11 show the chief components of the instru-
ments.

Electrical impulses of various frequencies are produced in the "tone generator'^
which contains anumber of "tone wheels" driven at predetermined speeds by a
motor and gear arrangement. Each tone wheel is asteel disc similar to agear^
with high and low spots, or teeth, on its edge (see figure 12). As the wheel
rotates these teeth pass near apermanent magnet, and the resulring variations
in the magnetic field induce avoltage in acoil 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.
Anote played on either manual of the organ consists of afundamental pitch and
anumber of harmonics, or multiples of the fundamental frequency. The fundament
al and eight harmonics available on each playing key are controllable by means
of drawbars. By suitable adjustment of these controls the player may vary the
tone colors at will. The M-lOO Console has several preset tabs which make sever-
al pre-selected tones available,
MODEL M
Mixed tones from the manuals are amplified and then pass through the vibrato
mechanism, the expression control, and additional stages of amplification before
reaching the loudspeaker -
MODEL M-2i M-3i M-lOO
Mixed tones from either the upper or the lower manual may go through either the
"vibrato" channel or the "No Vibrato" channel, depending on the position of the
corresponding vibrato selector of "Vibrato Cancel" tabs. (The upper manual is
called "Solo" on the selector tab of the M-2 and M-3 to indicate that it is
best suited for playing melody or solo parts of the music.) The tones are then
combined and passed through the expression control and additional stages of
amplification before reaching the speaker(s)-
MODEL M-3» M-lOO
Percussion tones are produced by borrowing asignal from the upper manual 2nd
harmonic drawbar, 3rd harmonic drawbar, or both, amplifying it, returning part
of the signal to the same drawbar, and conducting the balance of the signal
through push-pull control tubes where its decay characteristics are controlled.
The percussion signal is then combined with the signal from the manuals after
the vibrato system but before the expression control. The control tubes are
keyed through the 6th harmonic key contacts and bus bar.
The pedal tones do not require drawbars for tone color variation, because they
are produced as complex tones by special tone wheels. From the pedals these
tones go to apedal amplifier, where the attack and decay characteristics are
controlled. The single pedal drawbar adjusts the volume of the pedals relative
to that of the manuals, and the pedal signal than is combined with the signal
from the manual before passing through the expression control, but after the
vibrato system.

CONSTRUCTION AND OPERATION OF COMPONENTS
In reviewing this section refer to the schematic circuits of the entire organ
systems in the back of this manual. Connections between components are shown in
the wiring diagrams and control assembly wiring drawings, also in the back of the
manual,
MOTORS AND POWER SWITCHES
The tone generator assembly in which all tones of the organ originate, is
driven at constant speed by asynchronous motor, located at the left side as you
look in at the back of the Console. Attached to it is the vibrato scanner. As
the synchronous motor is not self-starting, it must be brought up to speed by
astarting motor at the opposite end of the generator.
The procedure for turning on the organ is as follows: Push the "start'' switch
up (M-3, M-lOO) or in (M, M-2) and hold it for approximately eight seconds.
This allows time for the starting motor to bring the generator up to slightly
above it synchronous speed- While still holding the "start" switch, push the
"run" switch upward to its "on" position. This turns on the synchronous motor
and at the same time introduc,es aresistor in series with the starting motor
to reduce its power- Hold the "start" switch about four seconds longer and then
release it-
During this time the braking action of the synchronous motor, together with the
reduction in power of the starting motor, brings the system to synchronous
speed so that the synchronous motor can carry the load.
To turn off the. organ, push the "run" switch downward to the "off" position.
a
TONE GENERATOR
All tones of the organ originate as electrical signals in the tone generator
assembly. The M, M-2 and M-3 contains 85 tone wheels while the M-lOO has 87,
Each of these wheels has various numbers of teeth, with suitable gears for driv-
ing them at various speeds from amain shaft extending along the center. Each
pair of tone wheels is mounted on ashaft and between them is abakelite gear
held between two coil springs, forming amechanical vibration filter. As the
gear is not rigidly attached to the shaft, any pair of wheels which may be
stopped accidentally will not interfere with the operation of the others.
Adjacent to each tone wheel is amagnetized rod with apick-up coil wound on
it. These magnets extend through the front and back of the generator, and are
held by set screws which can be loosened in case adjustment is ever necessary.
Figure 13 shows where to find the magnet for any frequency number. In this
drawing the dotted lines indicate frequencies whose tone wheels are on the
same shaft.
On top of the tone generator assembly are small transformers and condensers
,
forming tuned filters for the higher frequencies. They are not likely to need
replacing. In case one filter becomes inoperative, both the transformers and
condenser must be replaced with amatched set from the factory. Figures 14,
15 »16 and 17 show the locations of these filters on the indicated models. A
few frequencies use untuned filters consisting of coils alone.

The output frequencies of the tone generator are numbered ,for convenience, in
order of increasing frequency. The lowest, number 1,is about 32 cycles per
second, and the highest, number 91, is about 6000 cycles per second. Frequency
numbers 1to 12 (1 to 13 on M-lOO) are used for pedals; numbers 13 to 17 (14 to
17 on M-lOO) are omitted; and numbers 18 to 91 are used for the manuals.
In case any generator frequency is weak or absent, refer to "Practical Service
Suggestions" for the procedure to be used in locating and correcting the trouble.
The output terminals of the generator consist of solder lugs mounted on the fil-
ter transformers, to which the manual cable and pedals are connected* The fre-
quency numbers of all terminals are indicated in Figures 14, 15, 16 and 17.
MANUALS
Musical frequencies from the tone generator go through the manual cable to term-
inal strips on the two manuals and from them to the key contact springs-
Each of the two manuals has forty-four (44) playing keys, or approximately
3-1/2 octaves. The two manuals do not cover exactly the same pitch range, but
they are arranged so that keys of like pitch are in line. Middle "C" is the first
Con the upper manual and the key in line with it on the lower manual.
Under each key are anumber of contact springs (for the fundamental and har-
monics of that key) which touch an equal number of busbars when the key is press-
ed, (Some keys at the right end of each manual have fewer springs, as noted be-
low) -All contact springs and busbars have precious metal contact surfaces to
avoid corrosion, and the manuals are sealed to exclude dust so far as possible.
In case acontact becomes dirty in spite of these precautions, abusbar shifter
(shown in Figures 3, 5,7) is provided in each manual to slide the busbars end-
wise and thus provide afresh contact surface.
The busbar shifting mechanism is somewhat different on the M-lOO than on prior
models of the Hammond Orgam Models M, M-2 and M-3. Looking under the lower man-
ual on the left hand end, ablack wood end block will be observed. One half inch
from the front of this block is adrilled hole. Within this drilling is asmall
metal tongue with apunched hole. Using either long nose pliers or ahook, this
tongue can be moved in and out and it in turn moves the busbars. The upper man-
ual shifter is in a similar place, but requires removal of the generator dust
cover to gain access to it.
The key contacts are connected through resistance wires to the manual terminal
strips. The manual wiring chart Figure 18, shows how the contact of each key
are connected to the proper frequencies to supply the fundamental and harmonics
of that particular key. The blank spaces indicate that no key contact is used,
inasmuch as the highest harmonics of the highest keys are above the range of the
tone generator and are not required. Since the percussion control tubes in the
M-3 and M-lOO are keyed through the 6th harmonic busbar, the blank spaces in this
row have contacts connected to ground through resistance wires.
The busbars of each manual, each one carrying acertain harmonic, are wired to
the harmonic drawbars for that manual in the M, M-2, M-3 and through the "Draw-
bars" tab in the M-IOO-
8