Kenwood KACX-20 Service manual
POWER AMPLIFIER
This product uses Lead Free solder.
Accessories
(W01-1606-05)
Screw set
(N99-1794-05)
Dressing Panel
(A21-6570-01)
Fuse (30A)
(F52-0015-05)
KA C-X20
SERVICE MANUAL
© 2006-12 PRINTED IN JAPAN
B53-0484-00 (N) 584
KA C-X20
ISO AMP
IC12
LINE IN
LINE OUT
LINE IN R
LINE OUT R
L
L
ISO AMP
IC16
(X08-432)
MO/ST
IC1
HPF
40-200Hz
IC3
LPF
40-200Hz
IC1
HPF
40-200Hz
BLOCK DIAGRAM
FILTER
LPF/OFF/HPF
REMOTE
CONTROL
f,GAIN
15V
IC2
-1
SENS
IC2
f=40-100Hz
GAIN=0-18dB
IC4,5
ISF
15,25Hz
IC4,5
ISF
15,25Hz
OFF/15/25
ISF
IC7-9,13.15
BASS
BOOST
40-100Hz
BASS
BOOST
40-100Hz
Q1,2,16-18
AVR
Q241
MUTE
Q242
MUTE
Q601-606
CONTROL
IC5,Q3-14
POWER AMP
D.D. CON.
Q201-229
SP OUT L
Q201-229
SP OUT R
P-CON
BATT
GND
COMPONENTS DESCRIPTION
● PREAMPLIFIER UNIT (X08-4320-10)
Ref. No. Application / Function Operation / Condition / Compatibility
IC1 HPF
IC2 Phase inversion amplifier (Lch only)
IC3 LPF
IC4 I.S.F 15Hz
IC5 I.S.F 25Hz
● AUDIO UNIT (X09-8570-10)
Ref. No. Application / Function Operation / Condition / Compatibility
IC5 DC/DC converter
IC6 Temperature detection comparator
IC7,8,13 Bass boost amplifier
IC9 For bass boost gain and frequency adjustments
IC12,16 Input isolation amplifier
IC15 Bass boost mix amplifier
Q1,2 ±15V AVR
Q3~8 FET for DC/DC converter
2
KA C-X20
COMPONENTS DESCRIPTION
Ref. No. Application / Function Operation / Condition / Compatibility
Q9~12 FET driver for DC/DC converter
Q13,14 FET driver control for DC/DC converter
Q15 Temperature detection control circuit
Q16,17 ±15V for AVR control
Q18 ±15V AVR constant current
Q201~204 Power amplifier initial stage differential operation
Q205~208 Power amplifier second stage differential operation
Q209,210 Current mirror
Q215~218 Current limiter
Q219 Shock noise prevention circuit
Q220,222~227,229 Power amplifier final stage
Q241,242 Power amplifier mute
Q243,244 Power amplifier initial stage constant current
Q281~284 Power amplifier ATT
Q601,615~618 Shock noise preventing circuit when power is turned on
Q602 P-Con OFF detection
Q603 Mute driver
Q604,605 P-Con control circuit
Q606 Over voltage detection
Q609 Power supply for fan
Q610 Over current detection
Q611,612 DC detection
Q613,614 DC detection For latching
Q621,622 For LED control
ADJUSTMENT
NO. ITEM
1
IDEL VR3 (Lch-2) voltmeter between
CURRENT VR4 (Rch-1) check land Lch-2, or between Rch-1 and Rch-2, please repeat
ALIGNMENT
POINT
VR1 (Lch-1) Connect a DC After Power on 5minutes
VR2 (Rch-2) (Refer to PC BOARD) 1 and 2 several times for adjustment.
METHOD ALIGN FOR NOTE
2.0mV
Since there are interferences between Lch-1 and
3
A B C D E
1
Q605
KAC-X20
1
PC BOARD (FOIL SIDE VIEW)
AUDIO UNIT X09-8570-10 A/2 (J76-0346-11)
X09 B/2
D616
W84
Q610
R630
C610
R634
R607
R626
R619
D205
R617
BE
C602
E
R652
BC
K
R235
W83
R280
R635
R632
BE
Q613
Q602
B
C601
BE
R657
C604
D610
W64
B
A
E
EBC
W62
W80
W71
W76
W79
W77
W67
D255
R629
C223
W70
Q614
BE
R631
C607
BE
BE
C609
Q611
Q612
C603
D604
W72
W73
R606
W74
W75
D607
Q622
D608
C605
R616
W65
R247
D613
R610
D605
C20
Q225
R249
W66
R615
R613
R253
R633
W68
W69
D612
R231
W63
R612
W313
R29
C221
C608
D606
Q217
BE
R620
R621
Q606
R656
R653
D209
W61
R5
W31
W312
W60
EB
Q604
R611
BEBE
R614
P1
W59
W58
C12
C225
W133
BE
R282
D262
W325
R149
R134
14 8
IC9
R1
W132
C207
R273
C144
IC13
58
C133
C125
R142
71
D253
D254
R213
C209
Q283
BEBE
R275
C140
R163
R289
14
C127
W321
R136
R137
W324
R170
R669
W127
R38
R39
R171
C4
W322
W131
W130
C43
W323
D2
R37
BEBE
Q16
W129
BE
Q616
C618
W128
W320
C128
C2
R31
C613
W141
WH1
D609
13
2
RED
R272
3
Rch-1 2.0mV
DC voltmeter
4
5
6
Rch-2 2.0mV
DC voltmeter
W178
CN1
W177
W176
214
113
W175
W352
W174
R41
C118
C42
C40
R151
R152
C39
R40
C117
R901
C23
R36
D103
W172
C41
C110
IDLE R1
W173
C106
W351
C109
C55
C103
IDLE R2
R111
R122
D102
R47
C108
C107
C104
B
E
A
W170
W171
Q226
K
B
E
D204
K
B
E
R118
C115
C111
85
IC12
R109
R107
W164
J1
VR4
VR2
R258
EEC
BC
K
R234
B
A
Q220
D208
R240
B
A
Q224
EC
R116
C113
W349
41
C901
R105
W350
R103
C101
R101
R114
W167
R260
R226
W168
W169
W166
R104
C102
W161
W162
R112
W163
R262
D210
W160
R113
W165
R108
R102
EB
R254
R243
R119
C112
C116
85
IC16
R110
W348
R48
C56
C222
R232
Q218
W158
W159
R246
BE
Q216
R117
41
C902
R106
C105
R250
R238
C220
R230
R290
C114
D101
D206
R236
C218
C214
R214
C210
R115
C216
W157
W346
C208
W345
W347
R121
W156
Q208
R210
R120
A
TH601
K
W154
R218
Q210
BE
Q206
BE
R206
C206
R274
BEBE
Q284
W344
R45
W343
R46
C137
W340
W341
BE
R208
R268
Q244
W342
Q204
C228
R212
Q242
R276
R167
R168
C153
B
E
R216
D261
R220
R222
C212
D152
C224
BE
R288
R286
R242
BE
R264
C264
R287
Q282
R162
W155
C143
D109
E
R224
W338
W153
W339
C142
R248
W152
R219
R221
R223
Q202
C202
R284
W149
C141
W150
W336
W337
R150
D108
Q222
R215
Q205
D251
D201
D202
BE
C204
R228
R266
D229
C126
R135
14
W151
R139
R179
D260
C211
R267
BE
Q243
R204
W148
R202
IC15
C134
R138
R140
C148
D295
R164
R160
R143
IC7
W334
R217
BE
R207
R241
W144
C203
W147
R166
W146
Q209
Q207
R205
W335
R203
W145
14
85
W331
58
R43
R169
EB
R227
W332
W333
W142
C205
Q201
C201
W143
C136
R132
BE
R209
R244
Q219
BE
C227
W330
BEBE
Q241
C145
W139
R158
W140
R133
42
C215
W329
R157
C217
C213
W137
W138
BE
R263
C263
R265
C139
W327
R252
R285
R201
R165
C138
W136
C135
W328
C44
W135
Q203
R211
W134
R141
13
C226
Q281
R159
R161
W326
J4
C5
C3
R2
D4
R32
C22
Q17
D3
C21
Q1
EB EB
Q18
W122
R662
BE BE
R667
R665
Q615
R668
W315
W316
R648
85
14
R651
W125
W126
R623
R638
D617
C129
W318
W317
W319
C147
G
W113
R663
R625
R666
W119
R51
R643
IC6
R647
W124
W120
R639
C617
R628
W121
D611
W123
C54 R50
814
IC8
17
W314
R44
C146
SD
R661
C616
R646
R624
R618
R649
W117
C156
R4
R636
Q618
R659
R658
C58
W118
C53
W100
W101
W102
W103
W104
W105
R52
W115
D618
R3
R637
R33
R660
BE
W114
C57
W111
W116
BE
Q603
W89
W98
W99
W96
W106
R664
Q617
D615
C614
W109
W107
W110
W112
C611
W108
W97
Q601
R608
BE
R627
R603
R604
R605
W92
W93
W94
W95 W78
W88
W90
C229
R406
W91
R609
D602
E
Q621
R622
Q609
Q2
W86
C606
W82
W81
D614
W87
W85
D603
B
D601
BE
7
4
JIHGF
C608
2
KAC-X20
X09-8570-10
1
Ref. No. Address
IC5 5I
IC6 4D
Lch-2 2.0mV
Lch-1 2.0mV
IC7 6C
IC8 6D
IC9 6D
R656
R653
612
DC voltmeter
DC voltmeter
IC12 5B
IC13 5D
IC15 5C
IC16 5C
Q1 2D
W309
R261
W310
Q217
5
BE
C221
53
W61
BC
K
D209
A
Q229
B
VR3
E
R251
E
R257
W36
IDLE L2
W308
EC
R245
W305
W306
W307
B
E
TH602
Q223
R271
K
W32
Q215
BE
B
A
D203
R233
W28
R237
R229
C219
EC
R155
W22
Q227
B
K
E
B
A
R225
IDLE L1
R239
D207
VR1
D6
W21
W20
W19
D5
Q2 2E
Q3 3H
Q4 4H
Q5 4H
Q6 4H
Q7 4H
Q8 5H
Q9 5I
Q10 5I
Q11 5H
2
Q12 5I
Q13 5I
Q14 5H
Q15 5I
Q16 2D
Q17 2D
Q18 2D
Q201 4C
Q202 4C
Q203 4C
Q204 4C
Q205 3C
Q206 3C
Q207 3C
Q208 3C
Q209 3C
Q210 3C
Q215 2G
Q216 4C
Q217 2E
Q218 2C
Q219 4C
Q220 4B
Q222 2C
Q223 2G
Q224 4B
Q225 2E
Q226 3B
Q227 2G
Q229 2F
Q241 4C
Q242 4C
Q243 4C
Q244 4C
Q281 4C
Q282 5C
Q283 4D
Q284 5C
Q601 5D
Q602 5E
Q603 5D
Q604 5F
Q605 5F
Q606 5E
Q609 6E
3
4
5
6
9
D606
Q606
R620
R621
L3
R6
C6
W49
W50
W53
W58
W57
Q605
W47
W42
W40
W44
W46
W48
W54
W52
W45
W55
W51
W56
C19
W35
W38
W43
W37
W605
R28
W39
W41
R5
W311
W312
W60
EB
Q604
R611
BEBE
R614
P1
W59
C7
W7
W18
R8
C9
R7
C8
C11
W31
W29
W30
W24
W23
W33
W25
W26
W27
W34
J3
TH605
C10
W603
W604
L2
C1
W8
W9
W10
W11
C18
R30
W12
W13
W14
W15
W16
W17
L1
D11
W601
W602
CN2
SDGSDGSDGSDGSDG
R11
Q3
R54
Q5
R9
R56
Q7
R12
Q4
W304
R55
Q6
SDG
Q12
Q9
R10
R57
R13
R14
R16
R15
Q8
Q11
BE BE
Q14
C15
R21
R17
R26
R20
C14
R23
R22
C13
R18
R27
D1
W4
D10
Q13
D8
W5
18
D9
R19
W6
R35
D7
BEBEBEBE
Q10
C24
916
IC5
R25
R24
C17
R34
W301
R650
R53
W302
W303
C16
Q15
B
E
R49
W3
W1
W2
Q610 3E
Q611 5E
Q612 5E
Q613 5E
Q614 4E
Q615 3D
Q616 3D
Q617 3D
Q618 3D
Refer to the schematic diagram for the values of resistors and capacitors.
Q621 5E
Q622 5E
7
5
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