Date:
April 20, 1995Sheet
1
of
1
SizeDocument Number
REV
B--- --- ---
1.0
Title
PREAMPLIFIER TYPE AO-28
MODEL B3, C3, RT3
GC23
.033
EF
TO
"VOLUME"
TABLET
C24
82PF
C22
24-90PF
C17
680PF
RADIO-PHONO
EXPRESSION
CONTROL
C16
.033
C6
30PF
C15
51PF
C2
39PF
R9
820K
R4
1.8M
R5
10M
A
C3
100PF
R6
47K
R3
270K
NON-VIB
CHANNEL
INPUT
5
1
62
7
V1
6AU6A
R8
470K
C5
.01
R10
3.9M
130V
R27
1.8M
R29
330K
+1.7 (V2)
2
1
3
V4A
12AX7A
145V
+280
C18
220PF
C20
220PF
R30
1.8M
R32
1.8M
R31
68K
R33
68K
60PF/SEC
R35
3.3M
+1.7V (V2)
7
6
8
V4B
12AX7A
R34
15M
140V
+280
R37
270K R39
330K
R38
390K
R36
330K
7
6
8
V3B
12BH7A
C26
30/25
R42
1200
+290
R41
100K
12V
R40
.3M
TONE
GBN
T3
CABINET
TO TONE
+205
335V
C25
.001
R97
4500
TO HTRS
T7
"BL"
C19
.0022
C21
.001
C35
150PF
DINPUT FROM
VIBRATO SCANNER
COUTPUT TO
VIBRATO LINE
C13
1.0
R7
2.2M
+280
+1.7 (V2)
C7
24PF
C11
.0047
C4
.33
INPUT FROM
MATCHING XFMRS
THRU VIBRATO
TABLETS
R13
4.7M
B
C8
100PF
VIBRATO
CHANNEL
INPUT
R14
10M
R16
47K
R12
270K
R18
10M
C12
.0047
5
1
62
7
V2 6AU6A
R15
2.7M
+290
2
1
3
V3A
12BH7A
R25
100
R63
390K
C33
.0033
C34
.001
C33
.0022
R63
390K
R62
220K
C34
.001
R62
100K
C32
390PF
C35
390PF
"GY"
117VAC
60 HZ
375V
R91
900
C56
40/450
734 1
6
V8
6X4
+280
+290
C60
50/300
R95
4.7K
R96
4.7K
R94
4.7K
+37
+33
R99
180
R98
7500
R100
2.7K
R101
2.7K
T5
C57
40/400
C58
30/350
C56
10/350
TOP VIEW
THESE COMPONENTS GO BETWEEN
POINTS "P" AND "D" IN AO-28-1
LETTER ONLY) INSTEAD OF
AMPLIFIERS (WITH NO CODE
THOSE SHOWN AT LEFT
R24
22K
R22
820
95V
C10
.33
R20
2.2M
R19
470K
R17
1.2K
+280
R23
22K
R21
1M
C9
30/25
+1.7V
R48
470K
R47
47K
6
7
1
V5 6C4
T5
C28
.047
R53
47K
R52
47K
*
**
(* SEE NOTE)
C32 .0082
T6
R61
39K
P
2
1
3
V7A
12AU7A
CHANNEL BALANCE
SELECT FOR
(MOUNTED ON "P" TERMINAL)
V8
C56
C57
C58
T1
V1
V4
V3
EXPRES-
SION
CONTROL
T3
C9,C26
C59,C60
V5
V6
V2
V7
T4
T6
NK
MJ
HE
CP
DA
BL
GYBLBN
GG
F
N
+33
R60
30K
PERCUSSION
CUTOFF
+205
R58
4.7M
7
6
8
V7B
12AU7A
6
7
1
V6
6C4
C31
.33 R54
47K
+37
*
+205
C29
100PF
C30
25/25
R49
2.2K
H
PERCUSSION
CHANNEL
INPUT
T4
TO
PERCUSSION
SWITCH
R50
22
R51
4.7K
K
J
R55
82K
25V
+33
R56
22K
R57
1.5M
L M
TOPERCUSSSION
SWITCH
NOTE:
R52,R53,R54,C32 IN
AO-28-1 AMPLIFIERS
(WITH NO CODE LETTER ONLY)
SIDE VIEW
Date: December 11, 1995 Sheet 1 of 1
Size Document Number REV
E --- ---- --- 1.0
Title
B3/C3 SCHEMATIC
F
C22
24-90PF
R37270K
C17680PF C24
82PF
C23.033
VOLUMESOFT
NORMAL
E
C16.033
RADIO-PHONO
R29
330K
EXPRESSIONCONTROL
+280V
C2
39PF
1
6 2
7
5
V16AU6
C5.01
R9
820KTO BALANCE CHANNELS
R103.9M
C8
30PFC15
51PF
R10 - SELECT AT TEST
145V
130V
R8470K
OFF
ON
OFF
ON
VIBRATOGREAT
VIBRATOSWELL
R2
1MC1470PF
R4
1.8M
R5
10M
R6
47K
C3
100PF
A
T2MATCHINGTRANSFORMERUPPER
PEDALDRAWBARS
TYPICAL GROUP OF UPPER(SWELL) MANUAL DRAWBARS
TYPICAL GROUP OF LOWER(GREAT) MANUAL DRAWBARS
T1MATCHINGTRANSFORMER(LOWER AND PEDAL)
2 36
5
B
R13.9M
R3270K
(FROM V2)
R13
4.7M
C7
24PF
R7
2.2M
C4.33
R28
270K
R271.8M
+1.7V(FROM V2)
2
1
3
V4A12AX7
C11
.0047
60V
+280V
+1.7V
C18220PF
C20220PF
R30
1.8M
R32
1.8M
R31
68K
R33
68K
R34
15M
60PF/SEC
R353.3M
7
6
8
V4B
12AX7A
R39
330K
R38
390KR36
330K
140V
+1.7V(FROM V2)
+280V
G
G
BN
C25.001
T3
C2630/25R42
1200
R41
100K
12V
7
6
8
V3B
12BH7A
+290V
R40
300K
TONE285V
C19.0022
C21.001
D
7
6
8
V3B12BH7
R19470K
C12
.0047
R211M
R22820
R25
100
C13
1.0C
+290V
130V
100V
95VPERCUSSIONSIGNAL
R14
10M
R15
2.7M
R12270K
R16
470KC8
.0001
R171.2K
1
6 2
7
5
V26AU6
60V
R202.2M
UPPER MANUALPRESET PANEL
LOWER MANUALPRESET PANEL
012345678
UPPER MANUAL
LOWER MANUAL BUSBARS
91
(GEN 49-91)
BUSBARS
2 36
5
C10.33
+1.7V(TO V1,V4)
C930/25
R62
100K
R2322K
R2422K
C32
390PF
C34
.001R63390K
C35150PF
+280V
R44
22K
VIBRATOSWITCH
CLOSEDIN V1/C1
CLOSEDIN V1,V2,V3
CLOSEDIN V2/C2
CLOSEDIN V3/C3
SCANNER
181716151413121110987654321
C33.0033
7
R6133K
+205
+205
2
1
3
V7A
12AU7
C31
.33
T5
T6+37V
200V
7
6
8
V7B
12AU7
6
7
1
V5
6C4
T4
C29
100PF
C30
25/25
C28
.047
R49
2.2K
R48
470K
R47
47K
85V
H
THIRD
SECOND
OFF
ON
PERCUSSION1
44
(GEN 44-48)
4
1
(GEN 1-43)
GENERATOROUTPUTTERMINALS
R50
22
R51
4.7K
SOFT
PERCUSSIONVOLUME
J
K25V
R58
4.7M
R57
1.5M
FAST
PERC.DECAY
PERCUSSIONCUTOFF
200V
L
M
6
7 1
V66C4
SLOWR55 82K
R56 22K+33V
L1 L2
R6527K
C37
.004
C38
.004
R66
68K
R67
56K
R68
150K
R6030K
R59120K
+33V
L3 L5 L6L4
C39
.004
C40
.004
C41
.004
R70
150K
R72
180K
R74
180K
R76
180K
R69
39K
R71
33K
R73
18K
R75
12K
L13L12L11L10L9L8L7
C42
.004
C43
.004
C44
.004
C45
.004
C46
.004
C47
.004
C48
.004
L18L17L16L15L14
R7715K
C49
.004
C50
.004
C51
.004
C52
.004
C53
.004
C54
.001
T5
T4
T6
TOP VIEW
VIBRATO DELAY LINE
EXPRES-SION
T3C56C57C58
T1
C9,C26
C59,C60
1
2
NINE CONTACTS AND CONNECTIONS
SAME AS "B" EXCEPT THATUNDER "A#" ADJUST KEY ARE
THESE THREE DRAWBAR WIRES
NINE CONTACTS UNDER TYPICALPLAYING KEY.
GO DIRECTLY TO KEY CONTACTS.
3
NOTES:
C6050/300
R97
4500R98
7500
+37V
+205V
+290V
335V
R94
4.7K
6.0VHEATERS
T7
NORMAL
OFF
ON BL
R4612K
STARTSWITCH
RUNSWITCH
R85 5
R84 5
R8010
R82 47
R81 10
8 CONTACTS UNDERTYPICAL PEDAL KEY
TONEGENERATOR
L20 R83 470
PEDAL SWITCH
BUSBARS
TERMINALSTO GENERATOR
(SEE PEDALWIRING CHART)
(1000)HEATER(IF USED)
R88600
R86 20R87
250
STARTINGMOTOR
SYNCHRONOUSMOTOR
GY
117VAC50/60HZ
TO GND340VRMS PINS 1,6
375VR91
900
C57
40/400
C56
40/450
73
4 1
6
V8
6X4
R95
4.7K
C58
30/350
C56
10/350
R1002.7K
R101
2.7K
R96
4.7K
R99
180
+33V
+280V
NINE CONTACTS AND CONNECTIONSUNDER "B" ADJUST KEY.
4
5 NINE CONTACTS AND CONNECTIONSUNDER TYPICAL PRESET KEY.
PRESET PERCUSSION SWITCHUNDER "B" ADJUST KEY ONLY.
6 TO GENERATOR TERMINALS(SEE MANUAL WIRING CHART)
7 R61 SELECTED AT TESTTO BALANCE THE CHANNELS.
V8V3
CONTROL
V5V6V2V1V4 V7
Date: December 12, 1995 Sheet 1 of 1
Size Document Number REV
E B
Title
WIRING DIAGRAM - HAMMOND B3 OR C3
GYVIBLGNYLORRD
GYVIBLGNYLORRDBNBK
WH
GY
VI
BL
GN
YL
OR
RD
BN
WH
GY
VI
BL
GN
RESISTOR PANELAND PEDAL FILTERON BACK OFMANUAL ASSEMBLY
YL
OR
RD
BN
RD
BN
WH
GY
VI
BL
GN
R83
RESISTOR PANEL
YL
OR
RD
BN
WH
GY
VI
BL
GY
YL
OR
RD
BN
BNBK
A G# F# E D# C#DFGGY
VI
BL
GN
YL
OR
RD
BN
A G# F# EFGGY
VI
BL
GN
YL
OR
RD
BN
D# C#D
BK
1
BK
BK
BK
R85 R84 R81
OR
RD
R82
R86
BKYL
WH
GN
YL
R80
L20
BN
BNBL
PEDAL FILTER
RUN SWITCH
OFF
ON
ON
OFF
START SWITCH
BKBKBNYL
R87
BN
YL
RD RD
(BL)BK
91
LOWER MANUAL
LINEPANEL
13
GY
BN
GN
BL
BK
WH
WH YL
RD
VI
MATCHING XFMRT1 (LOWER MANUAL)
OR
GY
GN
BL
BNRD
YL
WH WH
VI
T2 (UPPER MANUAL)
BK
BK
OR
R1
R2
C1
BKBK
GN
BK
YL
PRESETSWITCH
UPPER MANUAL
BL
STARTINGMOTOR
SYNCMOTORGY
VIBRATO SCANNER 85
42
30
78
66
18
6 54
90
35
68
BL
YL
OR
RD
BN
RD
TONE GENERATOR
83
23
59
40
76
16
52
33
69
9 45
26
62
271
11
47
28
64
4 88
81
21
57
38
74
14
86
50
31
67
7 91
84
24
60
41
77
17
53
34
70
10
43
79
19
55
36
72
12
48
29
65
5 89
82
22
58
FREQUENCY NUMBERS IN CONSECUTIVE ORDER
46
27
63
3 87
39
75
15
51
32
80
68
20
8 56
44
37
25
73
61
13
1 49
1
YL
YL
GN
RD
BN
R46R59
WH YL GN
BK
GNGNYLWH
BL
COLOR CODE
BK BLACKBNRDORYLGN
BROWNREDORANGEYELLOWGREEN
PERCUSSION SWITCH(REAR VIEW, COVER REMOVED)
GN
YL GN
YLYL23456782345
5678910
11
57911
SCANNER TERMINAL NUMBERS
6782345678
R44
13
14
15
6912
15
16
17
18
VIBRATO SWITCHTERMINALS ONDRAWBAR BASE
PEDAL SWITCH
AC LINEJACK TO
TONE CABINET
OUTLET BOXGY BK
BL
BN
RD
GY BL BN
GY
BL
BN
G G F E C
BK
GN
BN
GNBKGN
P D A B
RD
YL
YL
BN
BL
1
BL
BN
GN
L N K M J H
YL
YL
RD
RD
PREAMP
VIBRATO LINE TERMINAL NUMBERS
151413121110987652 3 4
VIBRATO LINE BOX
CONTROL PANEL(REAR VIEW, COVER REMOVED)
181716
GN BLVIGYWHB
BLUEVIOLETGREYWHITEBARE
Table of ContentsB-3 illustrationC-3 illustrationIntroduction & DescriptionPedal Clavier, Tone Gen.Rear view of consoleTone GeneratorVirbrato, Percussion, Manual Chassis, PreampConsole Preamp, Tone Cabinet, Power Amplifier. Reverberation Unit, Overall Theory of OperationReverberation UnitOverall Theory of Operation (cont.)Power RequirementsInspecting, Stripping, Cleaning and LubricatingRem. & Repl. of Pluck-out PartsPedal ClavierLubrication & Approved LubricantsOilingInspecting Tubes, Cables & ConnectorsTesting with OhmmeterBlock DiagramPedal Switch AssemblyVoltage & Resistance MeasurementsResistorsSchematicSchematic (cont.)Receptacles & PlugsSchematicResistor Color CodeCoil MeasurementsAmplification System TroubleLocating and Correcting Defective TonesFrequency Numbers Assigned to Keys and PedalsFreq. #s (cont.)Freq. #s (cont.)Dead NotesLocation of Filters on Tone GeneratorTroubleshootingTroubleshooting (cont.)Preset Panel Tone SelectionAlignment of Coil AssembliesSchematicSchematic (cont.)Alignment of Coil Assemblies (cont.)Generator Output VoltagesAdjustment of Percussion Cut-off ControlAdjustment of Intermittent or Non-Operating KeysView of Manual AssembleView of Bus-Bar ShifterPedal Switch AssemblyDetailed Theory of OperationTone Wheel Tooth CountDetailed Theory (cont.)Starting MotorScanner diagramVibrato (cont.)Vibrato Scanner and SwitchVibrato SchematicManual Chasis AssemblyPedal Switch AssemblyPedal Switch Contacts IllustrationVolume Control and Pre-Amp AssemblyPercussion SystemPercussion (cont.)Reverberation UnitPower AmplifierReplacement of Tone GeneratorSchematic of Power AmplifierReplacement of Tone Generator (cont.)Replacement of Mixing TransformerReplacement of Playing KeyReplacement of Pedal Switch AssemblyReplacement of Manual ChasisReplacement of Switches for Start and Run MotorsReplacement of Start MotorReplacement of Run Motor and Vibrato Scanner AssemblyRep. of Run Motor (cont.)Replacement of TG FiltersRecommended Spare Parts ListRecommended Spare Parts List (cont.)Recommended Spare Parts List (cont.)Recommended Spare Parts List (cont.)Recommended Spare Parts List (cont.)Recommended Spare Parts List (cont.)Recommended Spare Parts List (cont.)Recommended Spare Parts List (cont.)Recommended Spare Parts List (cont.)Recommended Spare Parts List (cont.)Manual Assembly, CompleteGenerator CoverTone Cabinet AmplifierPR-40 Tone CabinetConsole with BenchPedal Switch AssemblyLower Manual Partially DisassembledPower Pack AssembleInterconnecting CablesTone Generator & Motor AssemblyVibrato Line AssemblyHammond Part NumbersHammond Part Numbers (cont.)Hammond Part Numbers (cont.)Hammond Part Numbers (cont.)Hammond Part Numbers (cont.)Hammond Part Numbers (cont.)Hammond Part Numbers (cont.)Hammond Part Numbers (cont.)SchematicSchematicSchematic
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