Pioneer PDP-4270XA Service Manual page 85

5
Flowchart of Failure Analysis for The Video System
⇒ COMP/S1
Image for the composite or S-video
signal is not displasyed.
Yes
Is the function correspondeing to
selected signal input selected?
Yes
Has the signal arrived at IC4701?
Yes
Which signal is not output,
main or sub signal?
Main
Is a signal output from
8 9
IC4701? (pins 42 and 45)
Yes
Has the signal arrived at IC5101?
(pins 148 and 158)
10 11
Yes
Is the communication between
each IC (VDEC, ASIC) on the
MAIN Assy and the microcomputer
normal?
Yes
Replace the MAIN Assy.
Waveforms
Input signal: PAL Color-bar (S terminal)
IC4701 - pin 42
8 9
V: 500 mV/div H: 20 µS/div
IC4701 - pin 47
12 13
V: 500 mV/div H: 20 µS/div
5
6
No
Select the corresponding signal
with the Input selector.
No
Check the flexible cable between CN8802 and CN4004.
Check the flexible cable between CN9003 and CN4005.
Check the cable between CN9001 and CN9202.
Check the cable between CN9002 and CN9205.
Check around input terminals.
Sub
Check around IC4701 and check the
No
communications between IC4701
and microcomuputer. If there was
no ploblem, replace the MAIN Assy.
Check the emitter-follower circuit
No
between IC4701 and IC5101 and
repair the failure points.
Check around the IC that is found to
No have failure in communication and
the microcomputer. If there was no
ploblem, replace the MAIN Assy.
IC4701 - pin 45 IC5101 - pin 148
10
V: 500 mV/div H: 20 µS/div V: 500 mV/div H: 20 µS/div
IC4701 - pin 49 IC5103 - pin 1
14
V: 500 mV/div H: 20 µS/div V: 500 mV/div H: 20 µS/div
6
7
No
Replace the FFCs or cables.
Is the screen of main side
Analog/Digital TV?
Yes
No
Is a signal output from
12 13
IC4701? (pins 47 and 49)
Yes
Has the signal arrived at
14 15
IC5103? (pins 1 and 2)
Yes
IC5101 - pin 158
11
V: 500 mV/div H: 20 µS/div
IC5103 - pin 2
15
V: 500 mV/div H: 20 µS/div
PDP-427XD
7
8
No
Specifications that does not
display in the sub-side.
Check the circuit
No
between IC4701 and IC5103 and
repair the failure points.
8
A
B
C
D
E
F
85