Acer RA19WAANU Service Manual page 26

5.6 Abnormal OSM display adjust problem
Check the input TTL level whether was changed when
pressed function keys on the P304 pin3, 5 (normal is high
level, when push buttom, generated low level plus)
Check the input TTL level of I305 pin20, 21 whether was
Failure Point
I305 is failure.
NG
OK
changed when pressed function keys.
(Refer to Table 1)
NG
OK
5. Troubleshooting (continued)
Failure Point
1) Function key wire disconnection.
2) Function key wire is failure.
3) Function key board is failure.
Failure Point
1) Printed wire broke among P304 pin3,R350 and I305 pin21
2) Printed wire broke among P304 pin5 ,R349 and I305 pin20
3) C358,C359 is short.
4) R374, R375 is short or open.
5) D327,D328 is short
ACER X193HQ 25
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