PDP-427XD
91
5678
56
7
8
C
D
F
A
B
E
Yes
No
No
Has the sound been emitted from
the Headphones?
Is sound muting set?
Is the volume set to 0?
No
Check the communications around the IC4701 and between the IC4701
and the microcomputer. If there was no ploblem replace the MAIN Assy.
Cancel muting, then check again.
No
Raise the volume, then check again.
4746
4948
Is a signal output from IC4701?
(pins 31, 32)
Yes
Yes
No
Check around the IC9001
and r
epair the failure points
.
Is a signal output from IC9001?
(pins 1, 7)
Yes
Replace the FFC.
NG
Replace the cables.
NG
Check the FFC between CN8802
and CN4004 or between CN9003
and CN4005.
Check the cables between CN9001
and CN9202 or between CN9002
and CN9205, or check around the
Headphones jack.
OK
B
42
IC4701 - pin 35
V: 1 V/div H: 400 µS/div
43
IC4701 - pin 36
V: 1 V/div H: 400 µS/div
46
IC4701 - pin 31
V: 1 V/div H: 400 µS/div
47
IC4701 - pin 32
V: 1 V/div H: 400 µS/div
Waveforms
Input signal: L/R 1 kHz
44
IC4701 - pin 25
V: 1 V/div H: 400 µS/div
48
IC9001 - pin 1
V: 1 V/div H: 400 µS/div
45
49
IC4701 - pin 26
V: 1 V/div H: 400 µS/div
IC9001 - pin 7
V: 1 V/div H: 400 µS/div
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