Acer A221HQV - Abnormal OSD Display Adjust Problem

5. Troubleshooting (continued)
5.1.5 Abnormal OSD display adjust problem:
Check the input TTL level whether is changed
when pressed function keys on the P310 pin 5,
6 (normal is high level, when push button,
generated low level)
OK NG
Failure Point
1) Function key wire disconnection.
2) Function key wire is failure.
3) Function key board is failure.
Check the input TTL level of I308 pin 50, 51
whether is changed when pressed function
keys.
OK NG
Failure Point
1) Printed wire broke among P310
pin5, R503 and I308 pin50
2) Printed wire broke among P310
pin6 ,R504 and I308 pin51
Failure Point
I308 is failure.
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ACER A211H/A221HQ