NAD C420 Service Manual page 16

U303: 74HCT00
1A 1
1B 2
1Y 3
2A 4
2B 5
2Y 6
GND 7
U901: LA1837
30 29 28
REG
AM
ALC
AM
MIX
OSC
BUFF
SD
COMP
FM
S-METER S-CURVE
FM
AM IF
DET
1 2
14 V
CC
13 4B
12 4A
11 4Y
10 3B
9 3A
8 3Y
27 26 25
AM
RF.AMP
AGC
AM IF DET
AM
S-METER
AM/FM
IF-BUFF
TUNING
DRIVE
GND
3 4 5 6
U402: NJM78M56FA
1
INPUT
24 23 22 21
3 rd 5 th
DECODER
ANTI-BIRIDE
P-DET
¯
VCO
304kHz
STEREO
DRIVE
V
CC
7 8 9 10
18
3
OUTPUT
2
GND
20 19 18 17
MUTE
STEREO
SW
FF FF FF
38k 19k
19k
11 12 13 14
16
PILOT
DET
15