NAD
SER
VICE
MANUAL
C 272
STEREO
AMPLIFIER
C
27
2
STEREO AMPLIFIER
SPECIFICATIONS
STEREO MODE
CONTINUOUS AVERAGE POWER
= 150 W (21.8 dBW)
OUTPUT INTO 8 OHMS OR 4 OHMS
(Min. power per channel, 20 Hz 20 kHz, both
channels driven, with no more than rated
distortion)
Rated Distortion
=
0.03%
(THD 20 Hz 20 kHz)
Clipping power
= 170 W
(maximum continuous power per channel).
IHF dynamic headroom at 8 ohms
= +2.3 dB
IHF dynamic power
(Maximum short term power per channel) 8 ohms:
= 230 W (23.6 dBW)
4 ohms:
= 410 W (26.1 dBW)
2 ohms:
= 520 W (27.2 dBW)
Damping factor
> 150
(ref. 8 ohms 50Hz)
Input Impedance
R = 20 kohms
C = 470 pF
Input sensitivity (for rated output into 8 ohms)
1.2 V¡À0.1V
Voltage gain
29 dB
Frequency response 20 Hz 20 kHz
¡À
0.3 dB
- 3 dB at 3 Hz/70 kHz
Signal / Noise ratio, A-weighted
> 100 dB ref. 1 W
> 120 dB ref. rated power
BRIDGED £¨ MONOPHONIC£©MODE
CONTINUOUS AVERAGE POWER
330 W 25.2 dBW£©
OUTPUT INTO 8 OHMS
(Min. power per channel, with no more than rated distortion)
IHF dynamic headroom at 8 ohms
3 dB
IHF dynamic power
8 ohms:
800 W (29.0 dBW)
IHF dynamic power
4 ohms:
1200 W (30.8 dBW)
DIMENSIONS AND WEIGHTS
Net Weight
12.5 kg ( 27.5 Ib)
Shipping Weight
14.2 kg ( 31.3 Ib)
Dimension (W × H × D)
435 × 133 × 350 mm
ALIGNMENT PROCEDURE (C272)
I.
INITIAL ADJUSTMENT (No load connected)
A. OUTPUT OFFSET VOLTAGE
1. Connect a DC Millivoltmeter to L Channel TP2 (DC) and TP8 (GND).
2. Turn unit "ON" and adjust VR301 (100ohms) to get a reading of 0V+/-30mV.
3. Connect a DC Millivoltmeter to R Channel TP5 (DC) and TP7, then adjust
VR401(100ohms) to get a reading of 0V+/-30mV reading on meter.
B. IDLING CURRENT
1. Connect a DC Millivoltmeter to L Channel TP1 (IDL) and TP3 (IDL), then adjust
VR302 (500 ohms) for 6~7.5mV reading on meter.
2. Connect a DC Millivoltmeter to R Channel TP4 (IDL) and TP6 (IDL), then adjust
VR402 (500 ohms) for 6~7.5mV reading on meter.
II. ISC ADJUSTMENT (WITH LOAD CONNECTED)
1. Connect a DC Millivoltmeter to Power Board CB725, and connect 4 ohms load to
both L&R speaker output terminals. Then feed 20kHz signal to Fixed In RCA.
2. Turn unit "ON" and try to get 15W on speaker output terminal. Then adjust VR701
(82kohms) to get a reading of 0V+/-10mV.
3. Change the load to 8 ohms and try to get 160W on speaker output terminals.
Then adjust VR701 (82kohms) to get a reading of 1.4V+/-30mV.
III. FINAL ADJUSTMENT
Repeat procedure A and B for offset voltage and idling current alignment respectively.
DRAFT
C702
22n/250V
C703
22n/250V
C715
C716
Q703
C1815
Q702
A1015
TC701
TIC116D
TC702
TIC116D
R707
1K
R713
22K
R709
100
R711
1K
R712
1K
R708
1K
R710
100
R714
22K
R716
0.025/3W
10%
R717
100
MF
1%
Q706
A1015
Q707
A1015
R718
9K1
MF
1%
R719
220K
!
!
!
!
RED
GRY
BLK
ORG
VIO
!
!
!
!
H1
H2
L1
L2
52.1V
AC
10%
10%
33.1V
AC
C704
22n/100V
C705
22n/250V
!
10%
10%
32.5V
AC
C711
22n/250V
C712
22n/250V
R701
R702
R703
R704
C721
22n/100V
C722
22n/100V
C723
1000u/100V
C724
1000u/100V
R721
1K
R7221K
R723
33/FS
R726
1K
R725
1K
R727
1K
R730
1K
R728
1K
R735
3K3
1%MF
R732
1K
R731
1K8
R734
9K1
1%MF
R724
33/FS
R733
1K
R737
22K
1%MF
C728
100u/25V
C732
10u/100V
C733
4u7/100V
C729
100u/25V
C737
22u/100V
C734
22n
100V
C731
47P
C730
47P
C735
22n
100V
Q708
KSC2690
Q710
C1775
Q711
C1775
Q709
KSA1220
Q712
A872
D703
1N4148
D704
1N4148
D706
1N4148
D705
1N4148
C725
47u100V
C726
47u/100V
R73622K
1%MF
C736
22u/100V
!
!
!
60.5V
AC
T701:
TI-65381:
AC
230V
AC
S1
AC
S2
+
+
-
-
B703
DB104
AC
S1
AC
S2
+
+
-
-
B704
DB104
AC
S1
AC
S2
+
+
-
-
B701
KBU1004
AC
S1
AC
S2
+
+
-
-
B702
KBU1004
C713
22n/250V
C714
22n/250V
D702
1N5401
10A
10A
0.5A
0.5A
Q704
A1015
Q705
C1815
R715
22K
C717
C718
C719
N.I.
C720
N.I.
1
2
3
4
7
8
9
5
6
10
11
12
T701
MAIN
TRANSFORMER
1
2
3
4
5
CZ702
5PIN
1
2
3
4
5
CB702
5PIN
1
2
3
4
5
CZ701
5PIN
1
2
3
4
5
CB701
5PIN
R720
100
R729
100
C727
0.1u
FUSEABLE
:
4
X
1/1W
AC-DET
ISC-C
ISC-S
4X10000uF/80V
+20%/-20%
C715--C718
+18V
R742
249
R743
249
R740
3K32
R741
3K32
C744
22u/50V
C745
22u/50V
C746
22n
100V
C747
22n
100V
IN
IC702
LM317M
IN
IC703
LM337M
C740
22n
100V
C741
22n
100V
+18V
-18V
C738
2200uF/50V
C739
2200uF/50V
C742
10u/50V
C743
10u/50V
D707
1N4148
D708
1N4148
1
2
CB703
2PIN
C706
0.1u
!
AC
S1
AC
S2
+
+
-
-
B705
DB104
C708
1000u/16V
C707
0.1u
R706
10K
1
4
5
6
7
9
10
2
8
T702
STANDBY
TRANSFORMER
PJ701
+12V
TRIG
R705
2K2
Q701
C1815
1
2
3
SW702A
AUTO
TRIG
1
2
RL701A
STAND-BY
RL701B
5V
D701
1N4148
IN
IC701
7805
C710
0.1u
C709
10uF
TGND
1
2
3
4
CZ706
4PIN
1
2
3
4
CZ706A
4PIN
1
2
CZ703
2PIN
F701
T4AL/250V(CE)
R738
200/1W
FS
R739
200/1W
FS
R740--R743=>1%
MF
YEL
BLU
WHI
BLU
YEL
1
2
CZ704
2PIN
+T5V
+T5V
TGND
R749
10K
D710
1N4148
R758
100K
1%
MF
R759
91K
1%
MF
R757
62K
1%
MF
R756
390K
1%
MF
C753
10u/25V
R754
1K
C750
10u/25V
R755
1K
C751
10u/25V
IC704A
TL082CP
C752
10u/25V
R751
1M
IC704B
TL082CP
R745
27K
MF
R752
1M
C748
1u/50V
C749
1u/50V
R750
10K
D711
1N4148
R746
270K
1%
MF
D712
1N4148
R748
100K
R753
100K
1%
MF
-18V
D709
1N4148
-18V
+18V
ISC-S
ISC-C
R772
56K
R773
56K
C758
330u/16V
C756
4u7/100V
C757
220n/63V
R764
10K
R769
56K
C755
47u/50V
1
2
3
4
5
6
7
8
IC705
uPC1237HA
+V34
R771
22K
R770
22K
D719
1N4148
D718
10V
Q715
A1015
C754
10u/50V
R762
22K
R763
10K
R765
10K
R768
10K
D713
1N4148
RL702B
36V
R766
220/2W
FP
L-OUT
R-OUT
R767
5K6
+V34
PROTECT-I
PT-OUT
AC-DET
+5V
1
2
CB707
2PIN
1
2
CB708
2PIN
LA
G1
G2
RA
LB
G3
G4
RB
CB715
BINDING
POSTS
1
2
RL702A
RL-LCH
1
2
RL703A
RL-RCH
1
2
3
4
5
6
7
8
CZ709A
8PIN
1
2
3
4
5
6
7
8
CZ710A
8PIN
C759
22n
100V
C760
22n
100V
C761
2n2
C762
2n2
L-OUT
R-OUT
+64V
-64V
1
2
3
SW704A
BG-SIGNAL
PROTECT-I
1
2
3
SW703A
SOFTCLIP
10
11
12
SW704D
BRIDGE
1
2
3
CZ711
3PIN
+18V
R779
10K
R777
10K
R774
4K7
D722
1N4148
D721
1N4148
D720
1N4148
R775
560
R778
4K7
R776
0
Q716
C1815
Q717
C1815
1
2
3
CZ712
3PIN
+18V
+18V
PT-OUT
4
5
6
SW702B
AUTO
TRIG
+5V
Q714
C1815
Q713
C1815
R761
22K
R760
22K
PROTECT-T
PROTECT-T
ISC-C
R783
25K
R782
25K
R785
1K
R784
1K
R781
1K
R780
1K
+68V
-68V
C764
10u/25V
C763
10u/25V
D714
24V
D715
24V
4
5
6
SW703B
SOFTCLIP
+64V
-64V
+18V
+68V
-68V
R744
100
Q718
C1815
R786
22K
D716
1N4148
+18V
-18V
C270
STANDBY
BOARD
LOUT
GND
+64V
-64V
-64V
+64V
GND
ROUT
MUTE-L
MUTE-R
POS90
POS90
POS80
POS80
SC-P
SC-P
SC-N
SC-N
OVERI-S
OVERI-S
-68V
-68V
+68V
+68V
BG-O
BG-S
1
2
CZ714A
2PIN
BG-G
4
5
6
SW704B
BG-GND
1
2
CZ713A
2PIN
LIN
GND
1
2
3
4
5
6
7
8
9
CZ61
9PIN
R612
1K
C62
100P
R62
220
MF
R64
2.2M
MF
Q62
2SK369
R68
1K
MF
R610
100/MF
Q65
2SA970A
Q68
2SD667A
Q66
2SB647A
D63
1N4148
D64
1N4148
C64
39P
R620
10/MF
C68
0.1u
C67
0.1u
MGND
1
2
3
4
5
6
7
8
9
CB61
9PIN
MLO
+18V
LOUT
LIN-
LIN+
GND
RIN+
RIN-
ROUT
-18V
R618
47/MF
R616
0
R614
10K
MGND
+18M
-18M
MGND
MLO
MRO
R621
N.I.
C611
N.I.
MR-FB
C270-INPUT
BUFFER
R66
N.I.
1%
MF
C610
47P
R611
1K
C61
100P
R61
220
MF
R63
2.2M
MF
Q61
2SK369
R67
1K
MF
R69
100/MF
Q63
2SA970A
Q67
2SD667A
Q64
2SB647A
D61
1N4148
D62
1N4148
C63
39P
R619
10/MF
C66
0.1u
C65
0.1u
MGND
MRO
R617
47/MF
R615
0
R613
10K
MGND
+18M
R65
N.I.
1%
MF
C69
47P
MR-FB
-18M
ML-FB
ML-FB
-18M
RIN
GND
2SA1943
BCE
2SA1943
2SA872
2SA1015
2SC1815
A872
EC
B
B649
TL431
LM317:
RAK
EC
B
TL431
2SB649
2SD669
3:IN
LM337:
1:ADJUST,2:IN,
123
LM7805
LM7805
1:IN
2:GND,3:OUT
2SC5200
R101
220
MF
C101
100P
R102
2M2
RCA1A
FIXED-L
R201
220
MF
C201
100P
R202
2M2
RCA1B
FIXED-R
1
2
3
SW705A
F/V
SW
4
5
6
SW705B
F/V
SW
R103
220
MF
C102
100P
R104
2M2
RCA2A
VARI-L
R203
220
MF
C202
100P
R204
2M2
RCA2B
VARI-R
A1
RV1A
1K
A2 RV1B
1K
R105
0
R205
0
C103
10n
63V
C203
10n
63V
C104
100uF
C204
100uF
1
2
3
CZ301A
3PIN
1
2
3
CZ401A
3PIN
+18V
-18V
C105
10uF
C205
10uF
7
8
9
SW705C
F/V
SW
10
11
12
SW705D
F/V
SW
BUF-R
BUF-R
123
LM317
LM337
1:ADJUST,2:OUT,
3:OUT
2.5Vref
+
-
Reference(R)
Cathode(K)
Anode
(A)
1
2
3
KSC2690
TL431
B647
EC
B
2SB647A
2SD667A
C613
0.22u
C612
0.22u
C765
22u/50V
R5
0
R6
0
C5
N.I.
C6
N.I.
P15
LOUT
P16
SGND
P7-64V
P9
PGND
P11
+64V
P13
LOUT
+64V
-64V
P17
ROUT
P18
SGND
P8-64V
P10
PGND
P12
+64V
P14
ROUT
C766
4n7/400V
GND
KAG
TIC116D
TIC116D
2SA970
GND
GND
C767
10u/25V
D723
1N4148
R788
100K
1%
MF
R-OUT
L-OUT
D724
1N4148
R789
270K
1%
MF
RL703B
36V
R790
2K2
+18V
!
R791
100K
R792
2K
R793
560
C407
22P/500V
C402
220P
C405
22P/500V
C415
0.1u
R402
22K
R403
100
MF
R412
100
R404
100
R413
39K
R405
39K
R414
100
R406
100
Q413
2SB649A
Q410
2SB649A
Q409
2SA1015
Q405
2SA1015
Q407
2SA872
Q406
2SA872
Q401
2SA872
Q411
2SD669A
Q412
2SC1815
Q408
2SC1815
Q404
2SC1775
Q403
2SC1775
Q402
2SC1775
R408
33
R420
33
R418
47K
1%MF
R459
10/1W
FS
R460
3R3/1W
FP
R415
1K
R423
100
MF
1%
R421
1K
MF
1%
R417
150
1%
R419
10K
0.5W
1%MF
R427
39K
R407
910
MF
1%
R416
10K
R428
100
MF
R411
1K
R410
10K
R426
100K
R424
100K
R409
100
MF
1%
D403
1N4148
D404
1N4148
D406
1N4148
D405
1N4148
C408
100P
Q414
2SD669A
R430
3R3
1W
FP
R432
510
1W
FP
R434
2K2
3W
FP
R438
3R3
1W
FP
R441
510
1W
FP
R444
2K2
3W
FP
R437
100
1W
FS
R429
100
1W
FS
R431
4R7
FS
R439
4R7
FS
R436
33
R440
33
L401
10uH
L402
10uH
R445
1K2
R446
820
Q415
KSC2690
Q417
2SC4937
Q422
2SC5200
Q420
2SC5200
Q418
2SA1837
R450
0.2
1W
FS
R452
0.2
1W
FS
R451
0.2
1W
FS
R453
0.2
1W
FS
R457
0.05
5W
R456
0.05
5W
R448
75
1W
FP
R449
75
1W
FP
R442
10K
R433
10K
C413
470P
500V
C414
470P
500V
Q419
2SA1943
Q421
2SA1943
D408
BAV21
D407
BAV21
C418
0.1u
100V
L403
1uH
R401
470/MF
R-FDBK
C401
10uF
C403
10uF/25V
C404
10uF/25V
C406
2200u/6.3V
C411
100uF
C412
100u/25V
R435
10K
R443
10K
C416
0.1u
100V
C417
0.1u
100V
C409
0.1u
100V
C410
0.1u
100V
Q426
2SA1015
Q425
C1815
R464
6K8
C421
10u
50V
R463
22K
R461
1K
R462
15K
C420
22n
100V
D409
1N4148
R465
22K
R454
0.2
1W
FS
Q423
2SA1943
Q424
2SC5200
R455
0.2
1W
FS
R422
9K1
0.5W
1%MF
1
2
CZ401
2PIN
1
VR401
180
R466
t=90
C
R467
t=80
C
RSCN
R-FDBK
D402
18V
D401
18V
IC402
TL431
IC401
TL431
1
VR402
500
R447
220
Q416
A1015
TP4
IDLING-I
TP5
OFFSET
TP6
IDLING-I
R468
0.2
1W
FS
Q427
2SA1943
Q428
2SC5200
R469
0.2
1W
FS
-V64R
+V64R
1
2
CZ708
2PIN
1
2
3
4
5
6
7
8
CZ710
8PIN
-64V
+64V
GND
ROUT
MUTE-R
POS90
POS80
SC-P
SC-N
OVERI-S
-68V
+68V
GND
BG-S
RSCN
RSCP
R-MU
Q429
2SC1775
Q430
2SA872
-V68R
+V68R
R425
100
R470
100
RSCP
+V68R
-V68R
+V64R
-V64R
R471
2K2
R-MU
R472
8K2
R358
100/0.5W
MF
1
2
3
CZ714
3PIN
BG-G
BG-G
BG-S
BG-S
BG-G
C307
22P/500V
C302
220P
C305
22P/500V
C315
0.1u
R302
22K
R303
100
MF
R312
100
R304
100
R313
39K
R305
39K
R314
100
R306
100
Q313
2SB649A
Q310
2SB649A
Q309
2SA1015
Q305
2SA1015
Q307
2SA872
Q306
2SA872
Q301
2SA872
Q311
2SD669A
Q312
2SC1815
Q308
2SC1815
Q304
2SC1775
Q303
2SC1775
Q302
2SC1775
R308
33
R320
33
R318
47K
1%MF
R359
10/1W
FS
R360
3R3/1W
FP
R315
1K
R323
100
MF
1%
R321
1K
MF
1%
R317
150
1%
R319
10K
0.5W
1%MF
R327
39K
R307
910
MF
1%
R316
10K
R328
100
MF
R311
1K
R310
10K
R326
100K
R324
100K
R309
100
MF
1%
D303
1N4148
D304
1N4148
D306
1N4148
D305
1N4148
C308
100P
Q314
2SD669A
R330
3R3
1W
FP
R332
510
1W
FP
R334
2K2
3W
FP
R338
3R3
1W
FP
R341
510
1W
FP
R344
2K2
3W
FP
R337
100
1W
FS
R329
100
1W
FS
R331
4R7/FS
R339
4R7/FS
R336
33
R340
33
L301
10uH
L302
10uH
R345
1K2
R346
820
Q315
KSC2690
Q317
2SC4793
Q322
2SC5200
Q320
2SC5200
Q318
2SA1837
R350
0.2
1W
FS
R352
0.2
1W
FS
R351
0.2
1W
FS
R353
0.2
1W
FS
R357
0.05
5W
R356
0.05
5W
R348
75
1W
FP
R349
75
1W
FP
R342
10K
R333
10K
C313
470P
500V
C314
470P
500V
Q319
2SA1943
Q321
2SA1943
D308
BAV21
D307
BAV21
C318
0.1u
100V
L303
1uH
R301
470/MF
L-FDBK
C301
10uF
C303
10UF/25V
C304
10uF/25V
C306
2200u/6.3V
C311
100uF
C312
100u/25V
R335
10K
R343
10K
C316
0.1u
100V
C317
0.1u
100V
C309
0.1u
100V
C310
0.1u
100V
Q326
2SA1015
Q325
C1815
R364
6K8
C321
10u
50V
R363
22K
R361
1K
R362
15K
C320
22n
100V
D309
1N4148
R365
22K
R354
0.2
1W
FS
Q323
2SA1943
Q324
2SC5200
R355
0.2
1W
FS
R458
8K2
R322
9K1
0.5W
1%MF
1
2
CZ301
2PIN
1
VR301
180
R366
t=90
C
R367
t=80
C
LSCN
L-FDBK
D302
18V
D301
18V
IC302
TL431
IC301
TL431
1
VR302
500
R347
220
Q316
A1015
TP1
IDLING-I
TP2
OFFSET
TP3
IDLING-I
R368
0.2
1W
FS
Q327
2SA1943
Q328
2SC5200
R369
0.2
1W
FS
-V64L
+V64L
1
2
CZ707
2PIN
1
2
3
4
5
6
7
8
CZ709
8PIN
-64V
+64V
LOUT
MUTE-L
POS90
POS80
SC-P
SC-N
OVERI-S
-68V
+68V
BG-O
LSCN
LSCP
L-MU
Q329
2SC1775
Q330
2SA872
-V68L
+V68L
R325
100
R370
100
LSCP
+V68L
-V68L
+V64L
-V64L
R371
2K2
L-MU
1
2
CZ713
2PIN
GND
GND
C322
10u/100V
C319
10u/100V
C422
10u/100V
C419
10u/100V
TP8
GND
TP7
GND
C323
0.1u
100V
C423
0.1u
100V
Q431
C2878
1%
1%
R797
10K
B-
B-
1
2
CB716
M-TEST
1
2
CB717
M+TEST
1
VR701
82K
R-OUT
L-OUT
1
2
CZ718
2PIN
1
2
CZ719
2PIN
1
2
CB719
2PIN
1
2
CB718
2PIN
1
2
3
CB720
68VTEST
+68V
-68V
1
2
3
CB723
18VTEST
+18V
-18V
T6.3AL/250V(AH)
1
2
3
CB724
N/A
TGND
1
2
CB725
PTEST
7
8
9
SW704C
BRIDGE
1
2
CZ705
2PIN
GND
ROUT
1
2
CB705
2PIN
R747
470K
-18V
NOTE:
1.
RESISTORS
ARE
CARBON
FILM
1/4W
5%
UNLESS
SPECIFIED.
FP
-
FLAME
PROOF
5%.
FS-FUSIBLE
5%
MF
-
METAL
FILM
5%.
CE-CERAMIC
CASE
5%
2.
ALL
CAPACITORS,
UNLESS
OTHERWISE
SPECIFIED,
ARE
50V,
20%
3.
COMPONENTS
WITH
"N.I."
MEANS
"NOT
INSERT".
4.
COMPONENTS
WITH
"
*
"
ARE
ADJUSTABLE
PARTS.
5.
COMPONENTS
WITH
"
"
ARE
SAFETY
CRITICAL
PARTS.
!
1
2
3
4
5
CZ705
230V
120V
C272
NAD
ELECTRONICS
INTERNATIONAL
Document
Sheet:
Date:
Date:
Date:
Drafted
PL
Checked
Approved
by:
by:
by:
Number:
REV.
Date
ECN
No.
DESCRIPTION
APPRO.
Project:
State:
PTA
Checked
by:
Date:
HS4_C272_B007
V3.0-MAIN.sch
TRIG
OFF
R799
2.2K
CHANGE
R744
TO
100
ADD
R799
1/4W
2K