No Sound; Troubleshooting - Sanyo PLC-SW30 Service Manual

Troubleshooting

● No Sound
Check following steps.
Is the audio signal
observed at pins 3 and
13 of IC5001?
Yes
Is the audio signal
observed at pins 5 and
8 of IC5003?
Yes
● Audio signal processing circuit
AV
BOARD
L
PC
AUDIO-IN R
L
AV
AUDIO-IN R
No
Check AUD_PC/AV switching circuit.
Check
AUD_PC/AV_SW (PC:H) signal is applied on pin 10 of IC5001
through Q5003, sent from pin 12 of IC3551.
Check Audio amp.and control circuit.
No
Check IC5003, audio-amp IC, and peripheral circuit.
MUTE signal (Mute:L) is applied on pin 4 of IC5003, sent from
pin 12 of IC1801
VOLUME signal is applied on pin 2 of IC5002., sent from pin 13 of
IC3551.
Check 5V_AUD power supply line.
Check audio output circuit.
Check speaker, connection of the terminal "K8F".
IC5001
AUDIO-SW
<4052>
12
Q5001
8
13
14
L
9
1
R
10
5
3
11
Q5002
10
Q5003
AUD_PC/AV_SW
IC301
P_SCLK2
SYSTEM
CONTROL
P_SCDA2
<PW168A>
DATA BUS
AUDIO-SW Switching Logic
AUD_PC/AV_SW at IC3551
AUD_PC/AV_SW at IC5001
IC5001, audio-sw
.
MAIN BOARD
IC5002 IC5003
VOLUME
<BA7655A> <LM4865M>
+
1 3 2
Q5004
2
Mute: L
Mute: H
12 13
IC3551 IC1801
D/A OUTPUT
CONVERTER EXPANDER
<M62393> <74LCX574>
PC AV
H L
L H
-38-
IC, and peripheral
AMP.
SP901
+
+ 5
1
3
-
8
4
Q5006
12
circuit.