Pioneer PDP-4280HD Service Manual page 55

5
Flowchart of Failure Analysis for The Video System
No video from Composite or S-VIDEO
=> COMP/S
Image for the composite or S-video
signal is not displayed.
Yes
Is the function correspondeing to
selected signal input selected?
Yes
Is the compornent cable is
connect to jack? (Input1 to Input3)
Yes
Has the signal arrived at IC4601?
(pins 85, 91, 72)
1
Yes
Which signal is not output,
main or sub signal?
MAIN
Is a signal output from IC4601?
(pins 42, 45)
3 4
Yes
Has the signal arrived at IC4801?
(pins 22, 26)
7 8
Yes
Is the communication between
each IC on the MAIN Assy and the
microcomputer normal?
Yes
Has the symptom been settled
when the MAIN Assy is replaced?
Yes
Replace the MAIN Assy.
Waveforms
Input signal: Color-bar
IC4601 - pins 85, 91, 72
1 2
V: 500 mV/div H: 20 μsec/div
IC4601 - pin 49 (Composite)
5 6
V: 500 mV/div H: 20 μsec/div
5
6
No
Select the corresponding signal
with the Input selector.
No
Disconnect component and
confirm again.
No
Check the flexible cable between
CN8804 and CN4004.
Check the flexible cable between
CN8803 and CN4001.
SUB
No
Check around IC4601 and check the
communications between IC4601
and microcomuputer. If there was
no ploblem replace IC4601.
No
Check the circuit between IC4601 and
IC4801 and replace broken parts.
No
Check around the IC that is found to
have failure in communication and
the microcomputer. If there was no
ploblem replace MAIN Assy
No
The panel is defective.
IC4701 - pin 57 IC4601 - pin 42 (S-video)
3
V: 500 mV/div H: 20 μsec/div V: 500 mV/div H: 20 μsec/div
IC4801 - pin 70 (Composite) IC4801 - pin 22 (Composite)
7
V: 500 mV/div H: 20 μsec/div V: 500 mV/div H: 20 μsec/div
6
7
NG
Replace the TANSHI Assy.
NG
Replace or reconnect flexible cable.
No
Is a signal output from IC4601?
(pin 49)
Yes
No
Has the signal arrived at IC4801?
(pin 70)
IC4601 - pin 45 (Composite)
4
V: 500 mV/div H: 20 μsec/div
IC4801 - pin 22 (S-video)
7
V: 500 mV/div H: 20 μsec/div
PDP-4280HD
7
8
5
6
IC4601 - pin 45 (S-video)
4
V: 500 mV/div H: 20 μsec/div
IC4801 - pin 26 (S-video)
8
V: 500 mV/div H: 20 μsec/div
8
A
B
C
D
E
F
55