NAD C 542, Service Manual

Page: 19 / 36

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MAIN BOARD
U101: CXA2581N
IC BLOCK DIAGRAM
AC SUM
AC VCA
EQ_ON/OFF
VC
D
Vcc
R
W/R
OM
R
W/R
OM
R
W/R
OM
R
W/R
OM
R
W/R
OM
R
W/R
OM
R
W/R
OM
VC VC
VC
DV
C
DV
C
V
OFST
V
OFST
B C A D
V
OFST
EQ
APC
23
RFG
24
BST
26
RFC
25
VFC
14
DVC
27
VC
5
GND
22
Vcc
1
LD
2
PD
12
SW
11
E
10
F
9
D
8
C
7
B
6
A
15
RF
A
C
30
DC_OFST
29
RFDCI
28
RFDCO
17
FEI
16
FE
19
TE_BAL
18
TE
21
CEI
20
CE
13
D
Vcc
3
EQ_IN
4
AC_SUM
-
+
-
+
VC
VC
DV
C
D
Vcc
-
+
-
+
-
+
-
+
D
Vcc
- +
-
+
D
Vcc
-
+
gm gm
VC
VC
V
OFST
DV
C
DV
C
-
+
+
VC
Vcc
APC-OFF (Hi-Z) R
W/R
OM
(H/L)
Vcc
+
MAIN BOARD
U202: BA6392FP
1 CH1OUTF 28 GND
2
F
INTER
FACE
REV
FWD
R
CH1OUTR 27 CH4OUTF
3 RCIN1 26 CH4OUTR
4 CH1RIN 25 VBIN
190K
100K
25K
25K
DRIVE
MUTE
5 CH1FIN 24 VSIN
6 VREFIN 23 VBIN
7 VREFOUT 22 VCC
8 GND 21 VCC
9 CH2FIN 20 CH3FIN
10 CH2RIN 19 CH3RIN
11 RCIN2 18 RCIN3
12 CH2OUTR 17 CH3OUTR
13 CH2OUTF 16 CH3OUTF
14 GND 15 MUTE
+
-
+
-
THERMAL
SHUTDOWN
CIRCUIT
F
INTER
FACE
REV
FWD
R
F
INTER
FACE REV
FWD
R
LEVEL
SHIFT
A1
B1
Y1
A2
B2
Y2
GND
VCC
B4
A4
Y4
B3
A3
Y3
1
2
3
4
5
6
7
14
13
12
11
10
9
8
MAIN BOARD
U403: TC74HC00AP
1
B A
2
3
4
Out A
-In A
+In A
V-
8
7
6
5
V+
OUT B
_In B
+In B
+ — — +
MAIN BOARD
U305, U306: OPA2134