AOC LM721A Service Manual page 30

4.U203-DATA OUTPUT
Measured DCLK(R240)
DVS, DHS (pin 117,116 from U203 )
Is the waveform ok?
DCLK around 48 MHZ , DVS=60.09Hz , DHS
around 80 KHz ?(refer to input
signal=640x480@60 Hz 31k, and LED is
Green)
Check U203 GM5120/2120
Signal output ER0~7,EG0~7,EB0~7
OR0~7,OG0~7,OB0~7
Is the waveform ok ?
Check U301,U302 LVDS IC
Signal output
Is the waveform ok ?
OK
OK
OK
NG , no transition
Replace GM5120 /2120 (U203) or
replace MAINBOARD.
If MainBoard being replace , please
do the DDC – content reprogrammed
Replace U301,U302 LVDS IC or
replace MAINBOARD.