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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 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
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
IC5001
AUDIO-SW
AU_SW2
1
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 15 of IC212 and it
is controlled by IC801 via the IIC bus.
Volume Min.: Low
Check audio signals at IC1651,IC1631, IC1632 and periph-
eral circuits.
4. No power supply at audio circuit.
Check 6V(6V AUDIO) power supply line.
A_SW2
A_SW1
A_MUTE
VOLUME
K8T
7
8
Q1681/Q1682
K16R
MUTE On: H
3,14
12
15
2
7
1
6
2
10
7
IC1652
IC1651
AUDIO
PRE.AMP
CONTROL
-39-
IC1801
I/O
EXPANDER
5
IC801
MAIN
4
CPU
49
IC212
D/A
SCL/SDA
2
15
3
IC1631
SPEAKERS
L-AMP.
K16N
7
L
14
5
3
17
4
R
7
1
14
5 5
2
17
IC1632
R-AMP.
DRIVE BOARD
29, 30
L
R
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