No Sound - Canon LV-S3E/D78-5423 Service Manual

Part 4: Troubleshooting

1.3 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
BOARD
PC
AUDIO-IN
AV
AUDIO-IN
Check IC5001, audio-sw IC, and peripheral circuit.
No
Check Audio amp.and control circuit.
No
Check audio output circuit.
AV
IC5001
AUDIO-SW
<4052>
L
12
8
R
14
9
L
1
10
R
5
11
IC301
SYSTEM
CONTROL
<PW168A>
AUDIO-SW Switching Logic
AUD_PC/AV_SW at IC3551
AUD_PC/AV_SW at IC5001
Fig. 4-3 Audio signal processing circuit
Check IC5001, audio-sw IC, and peripheral circuit.
AUD_PC/AV_SW (PC:H) signal is applied on pin 10 of IC5001
through Q5003, sent from pin 12 of IC3551.
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 speaker, connection of the terminal "K8F".
IC5002
VOLUME
Q5001
<BA7655A>
13
L +
1 3
R
3
2
Q5002
10
Q5003
AUD_PC/AV_SW
12 13
IC3551
P_SCLK2
D/A
CONVERTER
P_SCDA2
<M62393>
DATA BUS
PC
H
L
4-6
MAIN BOARD
IC5003
AMP.
<LM4865M>
SP901
+
+
5
2
1
3
-
8
Q5004
4
Mute: L
Q5006
Mute: H
12
IC1801
OUTPUT
EXPANDER
<74LCX574>
AV
L
H