Canon D78-5132, Service Manual

Page: 84 / 134

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-v12V) is applied at pins 1 and 9 of IC001.
Part 4: Troubleshooting
4-6
Fig. 4-2
PC/AV
AUDIO
SW
IC5001
AV BOARD
AUDIO BOARD
MAIN BOARD
Q5007
SP901
SPEAKER
L
R
15
3
2
4
16
12
16
13
12
16
14 4
12
4
6
8
1
3
2
8
10,11
1
13
2
12
14
Q5008
PC/AV-SW
Q1801
AUDIO
OUTPUT
IC001
BUFFER
IC851
DAC
IC431
I/O
EXPAND
.
IC1804
I/O
EXPAND
.
IC1803
I/O
EXPAND
.
IC1806
SYSTEM
CONTROL
&
SCAN CONV.
IC301
A
U
D
IO
I
N
A
U
D
IO
O
U
T
PC L
PC R
AV L
AV R
L
R
VOL
AUDIO
DAC
SDATA
SCLK
DAC
SDATA
SCLK
MUTE
MUTE
Q5041
Q5001
Q5003
Q5002
Q5004
Q5042
BUS