AOC LM-522 - Key Pad Board

LM-522 Service Manual
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4. U4-DATA OUTPUT
8.2.2 Key Pad Board
OSD is unstable or not working
Is Key Pad Board connecting normally?
Connect Key Pad Board
Is Button Switch normally?
Replace Button Switch
Y
N
N
Is Key Pad Board Normally?
Replace Key Pad Board
Y
N
Y
Check Main Board
NG
Measured X101 waveform is
normal?
Check NT68521A-XFG (U102)
Signal output (PIN64-69,
PIN50-55,PIN 41-46)
Is the waveform ok?
Replace X101
Check HS/VS input signal are
normal?
OK
Replace U101
OK
OK
Check relative component
NG
NG