background image
© 2002-12 PRINTED IN JAPAN
B53-0021-00 (N) 3379
POWER AMPLIFIER
KAC-7201/7251
SERVICE MANUAL
Illustration is KAC-7251.
KAC-7251 only
30
30
LINE INPUT SIDE
SPEAKER OUTPUT SIDE
DRESSING PANEL
KAC-7251
(A21-4268-03)
KAC-7201
(A21-4269-03)
HEAT SINK
(F01-1727-01)
FUSE
(F52-0015-05)
ACCESSORY
(W01-1606-05)
DRESSING PLATE
(B03-5024-04)
KAC-7251 only
SCREW SET
(N99-1587-05)
SCREW SET
(N99-1740-05)
KAC-7251 only
MODULAR CABLE
(E30-6240-05)
KAC-7251 only
CONNECTING CORD ASSY
(E30-6145-05)
KNOB
(K23-1076-03)
KAC-7251 only
CONTROL ASSY
KAC-7251 only


background image
2
ADJUSTMENT
No.
ITEM
INPUT
OUTPUT
RECEIVER
ALIGNMENT
ALIGN FOR
FIG.
SETTINGS
SETTINGS
SETTINGS
POINTS
Connect a cassette receiver or CD receiver.
Connect a DC
VR3 (L ch)
1
IDLE CURRENT
-
voltmeter between
VOLUME : 0
VR4 (R ch)
2.5mV
A
check land A and B
BATT.
VR3
Lch
R151
R152
MAX
check land
check land
MAX
VR4
Rch
L+
LINE IN
LINE OUT
Soldside view
L
R
R+
GND
P.CON
DC Voltmeter
2.5mV
DC Voltmeter
2.5mV
A
A
B
B
Fig. A
KAC-7201/7251


background image
4
3
A
B
C
D
E
F
G
H
I
J
1
2
3
4
5
6
7
W49
2
1
1
4
2
3
1
2
9
10
4
3
W67
W27
W25
W69
W71
W75
C232
W74
W76
W167
W23
W107
W114
W120
TH3
W122
W124
W125
W77
W84
W85
W44
W45
W51
W46
W244
W92
W29
W298
L4
L1
L2
W24
W129
W130
W93
W96
W108
W109
W110
W111
W98
W26
W86
W94
W95
W97
W279
W47
W48
W42
W41
W264
W259
W55
W58
W73
W80
W88
W89
W90
W91
W101
W118
W117
W100
W99
W104
W103
W102
R223
W22
C218
C217
R224
C213
C214
W81
W82
W83
W78
W79
R404
C403
R244
R210
R401
R406
W105
W106
W113
W116
W132
W123
W121
W119
R211
R201
R203
C201
R204
C204
C203
W115
W112
R263
R261
C227
R267
W163
W164
W165
W170
W186
W193
W199
R265
W187
W207
W203
R207
R113
R135
W208
R161
R131
R147
R143
R151
R129
R121
R123
W234
W258
R141
C127
C123
R133
W236
W232
W260
W231
TH2
W249
R145
R139
R149
R157
R15
C11
C13
R17
R18
R16
R1
R341
R342
R343
R29
R21
C51
R23
C15
C17
1
7
14
8
C5
R7
C6
C18
C16
R10
R340
R339
R37
R336
1
71
814
71
814
8
16
9
R27
W367
R28
W360
W363
W364
R334
R38 R36
W381 W369
C41
R67
R332
R331
W355
W354
W385
W382
C72
R31
W386
R39
R41
R32
C20
R63
R65
R66
W352
R302
R61
W357
W358
R49
R47
R48
C43
R51
R52
R70
R69
W365
W384
R34
R42
R43
R53
R54
R44
W351
R35
R333
R335
C71
C19
R33
R46
C24
R40
R301
W350
C23
R45
R24
C50
W362
W353
R8
R9
R30
C8
R2
W285
W371
W361
W370
W356
W68
W295
W273
VR2
VR4
VR3
VR1
W256
W257
W255
W245
C303
C28
R56
R55
R50
W359
C42
R68
R62
C26
R337
C21
C165
C53
C52
C22
W219
C301
C302
C304
W246
W240
W233
W297
C124
R134
R146
C128
R140
R162
R136
R138
W197
W201
W195
R273
W241
R274
W189
W148
W134
W150
W159
W158
W151
W161
W166
W147
W146
W140
W60
W135
W62
W54
W126
W127
W128
W131
R280
W53
C223
W63
C231
W192
R202
W87
C212
R212
R251
R271
R253
R247
R246
R255
R325
R324
R323
W270
R256
R260
C222
C221
C206
R250
R248
R249
R257
W56
W61
R160
W70
R159
C117
W65
W64
W21
C118
W59
W52
R320
R258
R259
W72
R321
C320
R322
W138
W141
W144
W152
W156
W160
R327
C228
R270
R328
R326
C321
W40
R245
C60
1
1
3
3
1
2
W43
C211
W243
W182
W176
R156
C122
C126
C106
R108
R132
R144
R122
R124
C116
W237
W227
W262
W238
R154
R130
R128
R148
W209
W229
R152
W250
W230
TH1
R142
R150
R158
W288
W278
W286
W291
W283
C40
C39
W210
W221
R206
W276
C3
C219
C1
R3
R5
R4
R6
R19
W368
R25
R11
R12
R26
C2
R13
R14
W277
W265
W253
W254
R22
R20
W248
W268
W281
W293
W284
W280
R338
W263
W261
W242
W252
W247
W215
W217
W211
R252
R254
W218
W224
W222
W212
W220
W216
C104
C114
C102
C210
R220
C130
R118
W235
R120
R164
R218
W223
R241
C233
W271
W269
W272
C112
R110
R216
R222
C202
W173
W157
W153
W180
W184
C208
W183
W190
R112
W179
W205
R126
R102
R104
R106
W239
W228
C29
C30
W226
C27
C25
W289
W282
C4
C9
W267
W266
R153
R221
W225
R127
W214
W213
W383
W206
W202
W196
W200
W194
W175
W177
W142
W143
W145
W133
R226
W299
C216
C121
C105
C109
R107
C125
Q115
Q125
Q12
Q14
Q16
Q11
Q13
Q15
J3
J1
D1
D2
S1
SWITCH UNIT
X16-2390-10 (J74-1534-02)
J2
BATT.
GND
P.CON
SPEAKER
OUTPUT
D23
Q121
Q107
Q113
D59
D101
Q109
Q7
D15
D13
Q119
D47
D46
IC1
D50
D24
D49
D2
D72
IC7
D74
D73
IC2
IC3
D71
D4
D48
D45
D3
D1
Q117
J5
J1
J4
SPEAKER
LEVEL
INPUT
REMOTE
LINE
OUT
LINE
IN
MONO
INPUT
SENSITIVITY
LPF
FREQUENCY
STEREO
OPERATION
12dB
OFF
BASS BOOST
LPF
HPF
FILTER
Q123
Q127
Q105
Q111
D7
Q3
Q103
Q101
Q102
Q104
Q110
D58
D17
D18
Q2
Q1
D41
D43
Q27
D28
D25
D34
D32
D30
D26
Q24
D31
CN1
CN3
X09 B/2
AUDIO UNIT X09-5600-1x A/2 (J74-1501-01)
Q34
Q26
Q25
Q28
D56
Q35
Q36
D27
D100
D10
Q6
D12
Q114
Q116
Q122
Q126
Q37
Q29
Q38
Q112
D102
Q8
D16
D14
Q106
Q108
Q4
D8
Q118
D55
Q120
WH1
S3
S2
S1
Q124
Q128
D60
R155
R137
R281
R400
W155
W168
W154
W162
R232
R231
R229
R239
R240
W149
W139
W171
W178
R215
C207
R219
R230
Q22
Q20
Q19
Q21
D38
D37
D11
Q5
R269
R268
C230
W191
W188
C226
R264
R266
C224
R262
W136
C225
R234
R233
W172
W169
W174
W181
W185
R109
R111
R115
R125
R163
R119
R117
R105
R217
R165
R100
W204
C107
C111
C129
C113
C101
R205
R101
C103
C229
C205
C110
C108
R116
R114
R103
C209
C12
C14
C100
C115
W137
R403
R402
R405
Q400
Q402
Q403
Q401
D400
D54
D40
D39
D9
D57
D78
R209
W57
W66
W50
ES D G
18
15
9
S D G
S DG
S D G
S DG
S D G
B
E
B
E
B
E
E
B
B
E
E
B
B
E
B
E
B
B
E
B
E
B
E
E
B
E
B
E
B
B
B
E
B
E
B
E
B
E
B
B
E
B
E
B
E
E
B
B
B
B
E
B
E
B
E
B
E
E
E
B
E
B
E
B
E
E
B
E
B
E
EB
EB
B
E
B
B
EB
B
E
E
B
E
B
E
E
B
E
B
E
B
E
B
B
E
E
B
E
E
B
E
E
B
E
B
E
B
18
16
9
IC5
C215
C402
C400
PC BOARD (FOIL SIDE VIEW)
X09-5600-1x
IC
Q
Address
13B
24C
35C
54F
74C
16G
26F
33D
45D
53E
66E
73C
85D
11
2G
12
2E
13
2G
14
2F
15
2G
16
2F
19
3E
20
4E
21
3E
22
4E
24
6H
25
6H
26
6H
27
6H
28
7H
29
7D
34
7H
35
7G
36
7F
37
7E
IC
Q
Address
38
7E
101
3D
102
5D
103
3D
104
5D
105
3D
106
5D
107
2D
108
6D
109
3D
110
5D
111
3D
112
5D
113
3E
114
5E
115
3E
116
6D
117
3C
118
6C
119
3C
120
6C
121
2E
122
6D
123
2C
124
6C
125
2E
126
6E
127
2B
128
6C
400
4H
401
4G
402
4G
403
4G
Refer to the schematic diagram for the
values of resistors and capacitors.
KAC-7201/7251 KAC-7201/7251


background image
6
5
A
B
C
D
E
F
G
H
I
J
1
2
3
4
5
6
7
WH1 CN1
Lch
Rch
J1
D3
D1
(2/4)
IC1
D47
D45
D4
D48
D2
D46
(3/4)
IC1
J4
IC1
(4/4)
S1
(1/4)
IC1
IC2
(3/4)
IC2
(2/4)
S2
(1/4)
IC2
IC2
(4/4)
(2/4)
IC3
S3
IC3
(3/4)
(4/4)
IC3
(1/4)
IC3
D7
D9
D101
D11
Q101
Q103
Q109
Q111
Q5
Q107
Q7
Q115
Q113
Q3
D15
D13
Q119
Q117
Q123
Q121 Q125
Q127
D8
Q4
D14
D16
Q120
Q110
D10
Q112
Q118
Q116
Q104
Q102
Q8
Q6
D102
Q108
D12
Q124 Q128
Q122
Q114
Q126
Q106
Q105
J2
D23
CN3
D32
D31
D30
D26
D25
D28
D27
Q25
Q24
Q27
Q28
Q26
REFERENCE
REGULA
T
O
R
OSCILLA
T
O
R
D34
D37
Q19
Q21
Q22
Q20
D38
D41
D43
Q29
D17
Q1
FAN
GND LINE
SIGNAL LINE
IC1-3
: NJM2058M
IC7
: TC4052BF(N)
IC5
: UPC494GS
Q1
: 2SD2375
Q2
: 2SB1548(P)
Q3,4,19,20,24,25,27,29,400,
401,403
: 2SC945(A)(Q,P)
Q5,6,34,35,37
: 2SC1845(F,E)
Q7,8,36,38,101-104 : 2SA992(F,E)
Q11-16
: FKV550T
Q21,22,28,402
: 2SA733(A)(Q,P)
Q26
: 2SA1534A(R,S)
Q105,106
: 2SA1123(Q,R)
Q107,108
: 2SC4137(V,W)
Q109-112
: 2SC2631(Q,R)
Q113-116
: 2SC2235
Q117-120
: 2SA965
Q121,122,125,126 : 2SC4467
Q123,124,127,128 : 2SA1694
D1-4,7-16,27,28,31,32,34,37-40,
45-48,55-60,78,101,102,400
: 1SS133
D17,26
: RD16JS(B)
D23
: RM4ZLF-J1
D24
: MA3056WA
D25
: RD7.5JS(B)
D30,54
: RD10JS(B)
D41
: FML22S
D43
: FML22R
D100
: B30-1669-05
ISOLATION
AMP
BASS BOOST
AMP
MIXIING AMP,
LPF,BUFFER
+15V
AVR
MUTING
SW (Lch)
1st-STAGE
AMP(Lch)
DIFFERENTIAL
CURRENT
MIRROR(Lch)
2nd-STAGE
AMP(Lch)
DIFFERENTIAL
DETECTOR
(Lch)
OVER LOAD
COMPENSATOR
(Lch)
TEMPERATURE
POWER AMP
DRIVER(Lch)
POWER AMP
(Lch)
1st-STAGE
AMP(Rch)
DIFFERENTIAL
MIRROR(Rch)
CURRENT
DIFFERENTIAL
AMP(Rch)
2nd-STAGE
DETECTOR
(Rch)
OVER LOAD
POWER AMP
(Rch)
DRIVER(Rch)
POWER AMP
TEMPERATURE
COMPENSATOR
(Rch)
DC
DETECTOR
OFFSET
SW
DRIVER
DRIVER
PRE-SW
SW
POWER
VOLTAGE
OVER
DETECTOR
MUTING SW
DRIVER
SW REGULATOR
CONTROL IC
D24
LINE IN
ST/MONO
INPUT
SENS
LPF FREQ
-15V
AVR
Q2
D18
SP OUT
J3
BASS BOOST
OFF(RM)/+12dB
SPEAKER
INPUT
LEVEL
D72
D71
4-ch
MULTIPLEXER
D74
D73
REMOTE
JACK
J5
Q12
Q14
Q16
Q11
Q13
Q15
D56
Q36
Q35
Q34
Q37
Q38
D58
D57
D59
D60
Q402
Q403
D400
Q401
Q400
D55
D100
D71,72
D49,50,73,74
RD8.2JS(B)
:
DA204K
:
POWER
LED
D78
D39
D40
D54
SW (Rch)
MUTING
IDLE
ADJ
IDLE
ADJ
LINE OUT
Lch
Rch
D49
D50
/LPF ON
HPF ON/OFF
B
A
J1
S3
D1,2 : 1SS133
CONTROL SW
BASS BOOST
D2
D1
2
11
2
1000P
1000P
R2
C2
1K
R1
1K
C1
10K
C4
R4
10u16
+
10K
10u16
C3
R3
+
7
C5
15P
R5
R7 10K
10K
5
6
4
10K
R9
C8
R8 10K
R6
10K
C6
15P
C9
8
10
9
11
C100
R100
10K
R10
0.01
0.01
R14
47K
R13
2.2K
C13
C14
10u16
10u16
C12
10u16
+
2.2K
+
+
R20
47K
47K
R21
R22
47K
10u16
C11
+
R19
62K
R16
62K
62K
R18
62K
R17
R15
1
2
R25 10K
3
12
13
14
R26 10K
C15
15P
15P
C16
10K
R11
R12
10K
C17 15P
C18 15P
1K
1000P
10K(A)
10K
R23
10K
R24
430
R27
R28
430
VR1
9
10
8
11
5
6
4
7
22K
R31
22K
R32
0.22
C20
0.22
C19
300
R33
300
R34
680
R35
220
R39
330
R37
680
R36
330 220
R38 R40
2.2K
R43
2.2K
R44
R41
2.2K
2.2K
R42
3
2
1
12
14
13
C23
100P
10K
R46 10K
100P
C24
22K
R48
22K
R47
6
5
7
4
0.47
C25
1.5K
R49
2.4K
R50
1.5K
R51
C26
0.22
C27
11
10
9
8
47K
R52
10u16
+
C28
10u16
+
C30
10u16
+
C29
R53
47K
47K
R54
3
2
1
13
12
14
R61
4.7K
4.7K
R67
47P
C41
47P
C42
11K
R68
47K
47K
10u16
+
C39
10u16
+
C40
220
VR3
2.2K
R101
22u25
+
C101
1000P
C103
13K
R103
10K
R205
1K
R107
1K
R109
4700P
C105
100
R111
6.8K
R105
47P
C107
330P
C111
1K
R113
+
C109
47u25
150
R125
+
C205
220u50
10
R207
6.8K
R121
1000P
C115
150
R119
150
R117
470P
C121
1.8K
R127
100
R131
4.7
R137
4.7
R135
470P
C207
1K
R219
470P
C209
1K
R221
100
R133
22P
C113
510
R129
6.8K
R123
13K
R115
33
R163
1/2W
4.7
R141
4.7
R139
680
R217
C123
470P
680
R215
220
R161
0.1
R153
0.1
R151
4.7
R145
4.7
R143
2W
2W
4.7
R147
4.7
R149
2W
R155
0.1
2W
R157
0.1
150
R104
C104
1000P
10K
R206
2.2K
+
22u25
R102
C102
4.7
R146
R150
R110
R108
1K
1K
13K
+
47u25
C110
150
470P
C128
R126
R134
100
4.7
R140
4.7
4.7
C210
C208
1000P
C116
R106
6.8K
R124
C106
4700P
R112
100
R114
C112
330P
1K
13K
R116
47P
C108
R130
510
6.8K
C130
22P
VR4
220
R122
R164
R132
6.8K
R128
1.8K
33
100
150
R120
470P
C126
R216
470P
R220
1K
R218
R154
0.1
2W
R142
680
R162
1K
R222
470P
680
220
R152
0.1
2W
2W
0.1
R158
R156
0.1
2W
4.7
R138
4.7
R144
4.7
R148
R136
4.7
R118
GND
Lch+
Lch-
Rch-
Rch+
F1
P-CON
C117
0.047
R159
4.7
R160
C118
4.7
0.047
BATT
L1
L2
680
R259
33K
R255
680
R258
10K
R256
100
R260
+
C222
47u25
10K
R257
10u16
C221
+
30K
R250
3.6K
R248
3.3K
R246
3.3K
R244
3.6K
R249
3.3K
R245
3.3K
R247
4.7K
R251
10u35
+
C206
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
10u16
+
C225
R263
1000P
R262
47K
R270
C224
16K
1K
+
C223
10u16
R261
10K
27K
R269
27K
R268
330K
R266
C227
2.2u50
R264
10K
10K
R267
91K
R265
+
C226
0.1u50
R281
1K
TH2
T
H3
TH1
4.7K
R239
10
R231
R229
75
1.5K
R233
R253
10K
33K
R271
R234
1.5K
R230
75
10
R232
R240
4.7K
L4
R274
C228
+
100u6.3
22K
10K
R273
+
C203
47u25
120
R201
13K
R203
+
C201
47u25
R69
R70
150K
R252
100K
R254
IC1
IC2
IC3
Q101,103
Q105
Q109,111
Q5,7
Q107
Q113,115,117,119
Q121,123,125,127
Q102,104
Q106
Q110,112
Q6,8
Q122,124,126,128
Q114,116,118,120
Q108
Q11-16
Q19-22
Q24
Q27,28
VR2
10K(C)
R202
120
+
C204
47u25
R204
13K
C202
47u25
+
F2
1
2
IC5
11K
R62
4.7K
R63
R66
11K
16
15
14
13
12
11
10
9
VDD
X2
X1
XCOM
X0
X3
A
B
1
2
3
4
5
6
7
8
Y0
Y2
YCOM
Y3
Y1
INH
VEE
VSS
2.2u50
C21
C22
2.2u50
R333
R334
220K
220K
220K
R335
220K
R336
1.2K
R338
1
3
7
5
9
2
4
6
8
10
L+
L-
R-
R+
C72
0.01
C71
0.01
47K
R332
R331
47K 100
R339
R340
100
9
10
L
L
B
H
HH
INPUT
H
A
L
L
X2,Y2
X3,Y3
X1,Y1
ON
X0,Y0
CHANNEL
R342
1K
R343
1K
1K
R341
10
9
1
2
3
1.2K
R337
R45
15
14
12
13
10
11
9
2
3
4
5
6
7
8
1
C214
1500P
R224
10
1/2W
R223
10
1/2W
C213
1500P
R211
33K
R212
33K
4700u56
C211
+
4700u56
C212
+
2.2u100
C230
2.2u100
C231
++
W29
R321
5.6K
51K
R320
10u35
C321
+
5.6K
R326
5.6K
R325
R322
24K
27K
R324
27K
R323
51
R327
R328
51
C400
0.01
12K
R401
12K
R404
2.2K
R403
C402
0.01
R402
10K
100u6.3
C403
+
R405
6.2K
R406
2.2K
C215
0.01
47K
R209
47K
R210
W27
W26
33
15 1/2W
R241
C233
0.01
4
3
2
1
0.1u50
+
C320
FAN
LED
GND
C60
0.01
1
3
4
2
(30A)
(30A)
R280
10K
1K
R400
C232
10u16
10
1/2W
R226
1800P
C216
W24
W23
W21
W22
3900u16
C217
+
3900u16
C218
+
C125
470P
VR3
C127
470P
22P
C129
470P
C122
470P
C124
VR4
22P
C114
1000P
C219
1K
R29
1K
R30
C165
4700P
R165
220
C51
15P
10u16
+
C53
C52
+
10u16
C50
15P
10u35
C229
+
R56
3K
0.47
R55
6.8K
0.33u50
C301
+
0.33u50
C303
+
R301
6.8K
+
C304
0.22u50
6.8K
R302
C302
+
0.33u50
S3
C43
470P
R65
4.7K
2.2K
2.2K
2.2K
W25
X09-5600-11
UNIT No.
X09-5600-10
NAME
MODEL
KAC-7251
KAC-7201
A
YES
NO
B
R335-338
YES
NO
T2
T1
T3
T4
4
3
2
1
+6dB
+12dB
+9dB
4
15.2V
8.3V
-15.2V
15.2V
-15.2V
15.2V
-15.2V
2.4V
5.0V
5.0V
0V
0.46V
0V
14.2V
3.3V
0V
5.0V
5.0V
14.2V
14.2V
12V
0V
14.4V
-3.3V
-8.3V
((X09- ) B/2)
(X09-5600-1x) (A/2)
IC5
KAC-7251/7201
IC7
SWITCH UNIT (X16-2390-10)
B LINE
B LINE
CAUTION : For continued safety, replace safety critical components only with manufacturer's recommended
parts (refer to parts list).
Indicates safety critical components. To reduce the risk of electric shock, leakage-current or resistance
measurements shall be carried out (exposed parts are acceptably insulated from the supply circuit) before
the appliance is returned to the customer.
· DC voltages are as measured with a high impedance voltmeter. Values may vary slightly due to variations
between individual instruments or/and units.
2SA1123
2SA1534A
2SA733(A)
2SA965
2SA992
2SC1845
2SC2235
B
C
E
2SC4467
E
C
B
2SC4137
B
E C
2SB1548
TC4052BF
DA204K
UPC494GS
NJM2058M
2SC2631
2SC945(A)
KAC-7201/7251 KAC-7201/7251


background image
7
EXPLODED VIEW (UNIT)
A
B
1
2
3
A
B
C
D
E
F
G
H
J
K
L
M
N
P
R
M6x6
M4x8
M4x6
3x10
4x12
2x8(BLK)
3x10(BLK)
2x6
3x6
3x8(BLK)
3x14(BLK)
3x12
3x8
2x8(BLK)
FLAT WASHER(
4)
: N07-0003-08
: N09-4026-05
: N09-4214-08
: N09-6117-05
: N09-6128-05
: N80-2008-45
: N80-3010-45
: N82-2006-46
: N89-3006-46
: N89-3008-45
: N89-3014-45
: N09-6118-05
: N89-3008-41
: N82-2008-45
: N15-1040-46
Ax2
Kx4
Kx4
Dx4
Mx6
20
Mx4
Nx4
Mx12
Gx2
Nx4
J
J
Kx3
B
R
G
Cx6
Dx4
20
P
X16-2390-10
S1
6
8
10
17
18
15
5
(CONTROL ASSY)
740
16
2
7
11
13
4
F2
F1
712
704
720
710
703
721
711
21
22
723
730
3
(X09-)
(B/2)
(X09-)
(A/2)
CONTROL ASSY
J1
(X09-)
(X09-)
(X09-)
S1
S2
S3
VR2 VR1
J
J
J
Gx3
Fx2
L
L
Jx2
H
E
E
J2
(X09-)
J3
(X09-)
J4
(X09-)
J5
(X09-)
Parts with the exploded numbers larger than 700 are not supplied.
KAC-7201/7251