Pioneer PDP-4270XA Service Manual page 86

1
A
Flowchart of Failure Analysis for The Video System
⇒ RGB
Image for the RGB input signal
is not displasyed.
Yes
Is the function correspondeing to
selected signal input selected?
Yes
B
Which signal is not output,
main or sub signal?
Main
Has the signal arrived at IC4901?
Yes
Is a signal output from IC4901?
C
(pins 30, 32 and 34)
16 17
Yes
Has the signal arrived at IC5101?
(pins 160, 164 and 172)
19 20
Yes
Is the communication between
each IC (VDEC, ASIC) on the
MAIN Assy and the microcomputer
normal?
D
Yes
Replace the MAIN Assy.
Waveforms
Input signal: PAL Color-bar (S terminal)
IC4901 - pin 30
16
V: 500 mV/div H: 20 µS/div
E
IC5101 - pin 160
19
V: 500 mV/div H: 20 µS/div
F
86
1
2
No
Select the corresponding signal
with the Input selector.
Sub
Is the screen of main side
Analog/Digital TV?
Yes
Has the signal arrived at IC4701?
No
Check the flexible cables between the CN8802 and
No
CN4004 or between CN9003 and CN4005 or around
of input terminals.
Check around IC4901 and check the
No
communications between IC4901
and microcomuputer. If there was
18
no ploblem, replace the MAIN Assy.
No
Check the circuit between IC4901 and
IC5101 and replace broken parts.
21
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.
IC4901 - pin 32
17 18
V: 500 mV/div H: 20 µS/div
IC5101 - pin 164
20 21
V: 500 mV/div H: 20 µS/div
2
3
No
Specifications that does not
display in the sub-side.
Yes
No
Is a signal output from
IC4701? (pins 47 and 49)
Yes
Has the signal arrived at
IC5103? (pins 1 and 2)
Yes
IC4901 - pin 34
V: 500 mV/div H: 20 µS/div
IC5101 - pin 172
V: 500 mV/div H: 20 µS/div
PDP-427XD
3
4
Replace the FFCs or cables.
Check around IC4701 and check the
No
communications between IC4701
12 13
and microcomuputer. If there was
no ploblem, replace the MAIN Assy.
Check the emitter-follower circuit
No
between IC4701 and IC5103 and
14 15
repair the failure points.
4