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