G No Sound - Sanyo PLV-70 Service Manual

Troubleshooting
No Sound
1. No audio signals at AV input circuit.
Check audio signals at pins 1, 13 (CG1), 5, 14 (CG2) and
2, 12 (VIDEO) of IC5011 on the AV Board. Check IC5011
and peripheral circuits.
2. Incorrect operation of Input mode switching.
Check AUDIO_SW1/AUDIO_SW2 switching signals at pins
9 and 10 of IC5011. The AUDIO_SW1/AUDIO_SW2 sig-
nals are output from pins 4 and 5 of IC1801. See the truth
table below for input mode selection.
Logic Table of IC5011
Pin 10 Pin 9
L L
H L
L H
AV BOARD
AUDIO-SW
PC_L/R
COMPUTER1
AUDIO IN
COMPUTER2
PC_L/R
AUDIO IN
VIDEO AV_L/R
AUDIO IN
Mode
COMPUTER 1
COMPUTER 2
VIDEO
MAIN BOARD
K10Q K8B
41
42
39
40
IC5011
K8T
AU_SW2
1 K16R
9
13
AU_SW1
10
K10T K16S
Q5008
L
5
3
3
14
Q5007
R
13 1
2
12
3. No audio output signal at speakers.
Check audio signals at pins 3, 4 and 1, 2 of K16U on M
Drive Board.
Check MUTE signal at pin 8 of K16R/K8T.
The MUTE signal is output from pin 48 of IC1801.
Mute On : High
Check MUTE signal at pins 3 and 14 of IC1652.
Check sound volume signal at pin 7 of K16R/K8T.
The VOLUME signal is output from pin 8 of IC2381 and it
is controlled by IC801 via the IIC bus.
Volume Min.: Low
Check audio signals at IC1655,IC1631, IC1632 and periph-
eral circuits.
4. No power supply at audio circuit.
Check 9VA power supply line.
EXPANDER
A_SW2
A_SW1
A_MUTE
VOLUME
7 8
MUTE On: H
3,14
12
L
15
7
R
2 10
IC1652
AUDIO
CONTROL
M DRIVE BOARD
-46-
IC1801
I/O
5
IC801
MAIN
4
CPU
49
29, 30
IC2381
D/A
SCL/SDA
2
8
3
IC1631
SPEAKERS
L-AMP.
K16U
14
5 3
17
4
1
14
5 5
2
17
IC1632
R-AMP.
L
R