Abnormal Screen - NEC LCD1501-BK Service Manual

4. Abnormal screen

Check the R, G, B video signal from computer
input on D-Sub R,G,B connector.
NG
OK
Check the R,B,G input signals on IC401 pin 2,
13, 20,respectively that their level is 0.7Vp-p
typical.
NG
OK
Is the pulse of the TTL level being output to
IC301 from the data line of IC401?
NG
OK
Check the PHD sync pulse output to IC301
pin27 from IC401 pin53 at TTL level.
NG
OK
Check the PVD sync pulse output to IC301 pin28
from IC401 pin54 at TTL level.
NG
OK
Check the PDE sync pulse output to IC301
pin30, from IC401 pin126 at TTL level.
NG
OK
Proceed section 7 "Checking the resolution change IC
movement".
Failure point
1) No R, G and B video signal output from host
computer. Check computer.
2) Video signal cable disconnection.
Failure point
In the case of the Red signal.(A Green and
Blue signal is the same path, too.)
Printed wire broke between D-Sub(R,G,B) and
IC401 pin 2,13,20.
Failure point
Printed wire broke between IC401 data line
and IC301
Failure point
Printed wire broke between IC401 pin53 and
IC301 pin53.
Failure point
Printed wire broke between IC401 pin54 and
IC301pin28
Failure point
Printed wire broke between IC401 pin126 and
IC301 pin30
6-7