No Sound - Canon LV-7355J Service Manual

1.3 No Sound

1) No audio signals at AV input circuit
• Check audio signals at pins14 and 15 of IC5011 on the AV Board. Check IC5011
and peripheral circuits.
2) Incorrect operation of VIDEO/COMPUTER mode switching
• Check AV/PC switching signal at pins 10 and 11 of IC5011. Check IC5011, IC801
and switching signal.
AV: Low, PC: High
3) No audio output signal at speaker
• Check audio signal at pins 1 and 3 of K8F on the Main Board.
Check MUTE signal at pin 1 of IC001.
Mute On: Low
• Check MUTE signal at pin 7 of IC1831, pins 7 and 13 of IC1881, and peripheral
circuit.
Mute On: High
• Check sound volume signal at pin 4 of IC001, and pin 14 of IC1831.
Check IC IC001, IC1831 and peripheral circuit.
Volume Min.: Low
4) No power supply at audio circuit
• Check 6V (6V AUDIO) power supply line.
AV BOARD
IC5011
AUDIO-SW
COMPUTER
PC_L/R
1
AUDIO IN
13
VIDEO AV_L/R
2
12
AUDIO IN
MONITOR Q5051
AUDIO OUT
Q5061
SPEAKER
K10U
IC001
AUDIO
Q5072
CONTROL
10
AV/PC
11
Q5031
15
4
2
14
Q5041
6
1
8
Q011
MUTE On: H
Q5081
MUTE
Q5082
Fig. 4-3
MAIN BOARD
IC2161
D/A
K3U
PC: H
AV: L
AV/PC
29
2
7
7
30 3
8
27
VOLUME
28
21
|
24
IC1881
BUFFER
MUTE AUDIO MUTE
31
7 13
32
MUTE On: H
K8F
1,3
4-7
Part 4: Troubleshooting
Q1816
Q1817
SCL2_5
79,78
SDA2_5
IC801
SUB
CPU
IC1831
D/A
Q1818
Q1819
14
SCL1_5
2
80,81
3
SDA1_5
7