Pioneer PDP-4270XA Service Manual page 88

1
A
Flowchart of Failure Analysis for The Video System
⇒ COMP/PC2
Image for the PC signal is not
displayed.
Yes
Is the function corresponding to
selected signal input selected?
Yes
Has the signal arrived at IC4901 ?
B
(pins 61, 62, 64, 66, 68)
33 34
31 32
Yes
Which signal is not output,
main or sub signal?
Main
Is a signal output from IC4901?
(pins 41, 43, 45)
36 37
Yes
C
Has the signal arrived at IC5301?
(pins 43, 48, 54)
39 40
Yes
Is the communication between
each IC (VDEC, ASIC) on the
MAIN Assy and the microcomputer
nomal?
Yes
Replace the MAIN Assy.
D
Waveforms
Input signal: Color-bar (PC XGA/60 Hz)
IC4901 - pin 61
31
V: 1 V/div H: 2 mS/div
IC4901 - pin 41
36
V: 500 mV/div H: 10 µS/div
E
IC5301 - pin 54
41
V: 500 mV/div H: 10 µS/div
F
88
1
2
No
Select the corresponding signal
with the input selector.
No Check the flexible cable between the CN9301
and CN4018 or around of jack.
35
Sub Is the screen of main side
Analog/Digital TV?
Yes
Check around IC4901 and check the communications
No
between IC4901 and the microcomputer.
38
If there was no ploblem, replace the MAIN Assy.
No
Check the circuit between IC4901 and IC5301.
41 If there was no ploblem, replace the MAIN Assy.
Check around the IC that is found to have a failure
No
in communication and the microcomputer.
If there was no ploblem, replace the MAIN Assy.
IC4901 - pin 62
32 33
V: 1 V/div H: 10 µS/div
IC4901 - pin 43
37 38
V: 500 mV/div H: 10 µS/div
2
3
No
Replace the flexible cable.
No
Specifications that does not
display in the sub-side.
IC4901 - pin 64 IC4901 - pin 66
34
V: 500 mV/div H: 10 µS/div V: 500 mV/div H: 10 µS/div
IC4901 - pin 45 IC5301 - pin 43
39
V: 500 mV/div H: 10 µS/div V: 500 mV/div H: 10 µS/div
PDP-427XD
3
4
IC4901 - pin 68
35
V: 500 mV/div H: 10 µS/div
IC5301 - pin 48
40
V: 500 mV/div H: 10 µS/div
4