Pioneer PDP-4270XA Service Manual page 87

5
Flowchart of Failure Analysis for The Video System
No video from component
⇒ COMP/PC1
Image for the component signal
is not displayed.
Yes
Is the function corresponding to
selected signal input selected?
Yes
Has the signal arrived at IC4901 ?
(pins 2, 4, 6)
22 23 24
Yes
Which signal is not output,
main or sub signal?
Main
Is a signal output from IC4901?
(pins 41, 43, 45)
25 26 27
Yes
Has the signal arrived at IC5301?
(pins 43, 48, 54)
28 29 30
Yes
Is the communication between
each IC (VDEC, ASIC) on the
MAIN Assy and the microcomputer
nomal?
Yes
Replace the MAIN Assy.
Waveforms
Input signal: Color-bar (Component 1080i)
IC4901 - pin 2
22 23
V: 500 mV/div H: 10 µS/div
IC4901 - pin 45
27 28
V: 500 mV/div H: 10 µS/div
5
6
No
Select the corresponding signal
with the input selector.
Check the flexible cables between the CN8802
No
and CN4004 or between CN9003 and CN4005
or around of pin jack.
Sub
Is the screen of main side
Analog/Digital TV?
Yes
Check around IC4901 and check the communications
No
between IC4901 and the microcomputer.
If there was no ploblem, replace the MAIN Assy.
No
Check the circuit between IC4901 and IC5301.
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 4 IC4901 - pin 6
24
V: 500 mV/div H: 10 µS/div V: 500 mV/div H: 10 µS/div
IC5301 - pin 43 IC5301 - pin 48
29
V: 500 mV/div H: 10 µS/div V: 500 mV/div H: 10 µS/div
6
7
No
Replace the flexible cable.
No
Specifications that does not
display in the sub-side.
IC4901 - pin 41
25
V: 500 mV/div H: 10 µS/div
IC5301 - pin 54
30
V: 500 mV/div H: 10 µS/div
PDP-427XD
7
8
A
C
D
IC4901 - pin 43
26
V: 500 mV/div H: 10 µS/div
E
87
8
B
F