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Part 4: Troubleshooting
1.2 No Sound
1) Main board
1. Check that the PC/AV switching signal is correct.
Pins 10 and 11 of IC5001 ...................AV : L, PC : H
2. Check that audio signal is observed at following points.
Pins 11-12(PC)/13-14(AV) of K10B/K50B
3. Check that the MUTE signal is correct.
Pin 5 of K5A .......................................Mute-On: H
4. Check that the MUTE signal is correct.
Pin 12 of IC1803 ................................Mute-On: L
5. Check that the PC/AV switching signal is correct.
Pin 16 of IC1804 ................................AV : L, PC : H
2) Audio board
1. Check that sound volume control signal is correct.
Pin 4 of IC001
2. Check that audio signal is observed at pin 2 of IC001.
3. Check the MUTE signal at pin 3 of IC001.
Pin 3 of IC001 ....................................Mute-On: H
4. Check that Vcc-voltage(+12V) is applied at pins 1 and 9 of IC001.
AV BOARD
PC L
PC R
AV L
AV R
R
L
SP901
SPEAKER
Q5041
Q5042
10,11
1
Q5007
PC/AV
L
15
AUDIO
13
SW
2
14
IC5001
12
R
Q5008
Q5001
Q5003
Q5004
Q5002
2
8
AUDIO
AUDIO
OUTPUT
3
MUTE
IC001
4
VOL
DAC
4
IC431
AUDIO BOARD
PC/AV-SW
MAIN BOARD
16
MUTE
12
Q1801
1
16
4
16
DAC
DAC
BUFFER
3
SDATA
14
6
SDATA
13
IC851
SCLK
SCLK
2
12
8
12
Fig. 4-2
4-6
I/O
.
EXPAND
IC1804
SYSTEM
CONTROL
I/O
BUS
&
.
EXPAND
SCAN CONV.
IC1803
IC301
I/O
.
EXPAND
IC1806
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