Canon D78-5532, Service Manual, Page: 71 / 119

1.5 No Sound
Check following steps.
●
Audio Circuit
Part 4: Troubleshooting
4-9
Check PC/AV-AUDIO switching circuit.
Check IC5001, audio-sw IC, and peripheral circuit.
Check signals "P_SCLK2" and "P_SDA2" at pins 13,14
of IC5001.
Sound volume and input selecting is controlled by
IC301<SYSTEM CONTROL> via the IIC bus.
Is the audio signal
observed at pins 10 and
21 of IC5001?
Yes
No
Check Audio amplifier circuit.
Check IC5031, audio-amp IC, and peripheral circuit.
MUTE signal (Mute:L) is applied on pin 1 of IC5031,
sent from pin 12 of IC1804.
Sound volume is controlled by IC301<SYSTEM
CONTROL> via the IIC bus.
Check 5V_AUDIO power supply line.
Is the audio signal
observed at pins 5 and
8 of IC5031?
Yes
No
Check audio output circuit.
Check speaker, connection of the terminal “K8F”.
Q5031
Q5061
Q5064
Q5063
Q5062
Q5036
Q5032
Q5033
4
1
30
9
27
22
14
13
21
8
12
5
10
Mute: H
Mute: L
K8Q
K3Y
K10Y
P_SCLK2
P_SD
A
2
MAIN BOARD
AV
BOARD
Q5034
IC5031
AMP.
<LM4889M>
L
R
L
R
L
R
PC
AUDIO-IN
AV
AUDIO-IN
SP901
IC1804
OUTPUT
EXPANDER
<74LCX574>
IC301
SYSTEM
CONTROL
<PW168A>
MUTE
IC5001
AUDIO-SW
<NJW1141>
L
R
AV
AUDIO-OUT
4
+
1
29
31
23
25
35
37
39
1
3
+
-
DATA BUS
OUT_DET