LM-522 Service Manual    
29 
 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