Acer RA19WAANU service manual Troubleshooting Abnormal OSM display adjust problem

5. Troubleshooting (continued)

5.6 Abnormal OSM display adjust problem

ACER X193HQ 25

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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)

NG

OK

Check the input TTL level of I305 pin20, 21 whether was

changed when pressed function keys.

(Refer to Table 1)

Failure Point

1)Function key wire disconnection.

2)Function key wire is failure.

3)Function key board is failure.

	NG	Failure Point
		1)	Printed wire broke among P304 pin3,R350 and I305 pin21
OK
		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

Failure Point

I305 is failure.