Pioneer PDP-4271HD Service Manual page 88

1
A
Flowchart of Failure Analysis for The Video System
No video from TV signal
⇒ COMP/S2
TV signal is not displayed on the
screen.
Yes
Is the input selecter set to TV?
(ANT-A or B)
Yes
B
Is a signal output normally from
the FE to IC4701? (pin 55, 57)
Yes
Which signal is not output,
main or sub signal?
MAIN
Is a signal output from IC4701?
(pin 47, 49)
3
Yes
Has the signal arrived at IC5101?
C
(pin 148, 158)
7
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.
D
Waveforms
Input signal: Color-bar
E
IC4701 - pin 45 (composite)
5
V: 500 mV/div H: 20 µsec/div
F
88
1
2
No
Set the Input selector to TV.
(ANT-A or B)
No
Check around the FE and check
the communications between FE
2
and microcomuputer. If there was
no ploblem replace MAIN Assy.
SUB
No
Check around IC4701 and check the
communications between IC4701
4
and microcomuputer.If there was no
ploblem replace MAIN Assy.
No
Check the circuit between IC4701 and
IC5101 and replace broken parts.
8
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 55, 57 IC4701 - pin 47 (s-video)
2 3
V: 500 mV/div H: 20 µsec/div V: 500 mV/div H: 20 µsec/div
IC7001 - pin 3 (composite) IC5101 - pin 148 (composite)
6 7
V: 500 mV/div H: 20 µsec/div V: 500 mV/div H: 20 µsec/div
PDP-4271HD
2
3
No
Is a signal output from IC4701?
Yes
Has the signal arrived at IC7001?
(pin 3)
IC4701 - pin 49 (composite)
4
V: 500 mV/div H: 20 µsec/div
IC5101 - pin 148 (s-video)
7
V: 500 mV/div H: 20 µsec/div
3
4
5
No
Check the circuit between IC4701 and
IC7001 and replace broken parts.
6
IC4701 - pin 49 (s-video)
4
V: 500 mV/div H: 20 µsec/div
IC5101 - pin 158 (s-video)
8
V: 500 mV/div H: 20 µsec/div
4