Read LG 37LH4000 / 37LH4010 / 37LH4020 (CHASSIS:LD91G) Service Manual online
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1. TV/CATV doesn’t display
TROUBLESHOOTING
2. DTV doesn’t display
Check the output data of TU1200 Pin 4,21,22.
Can you see the normal signal?
NO
Could you measure voltage of TU1200 &
IIC lines?
Are they all normal?
NO
You should check power line
& IIC lines.
YES
You should replace Main Board.
YES
Check the output of Main IC(IC100).
Especially you should check
The H,V sync and clock.
Can you see the normal waveform?
YES
NO
After checking the Power of Main IC(IC100) you
should decide to replace Main IC or not.
This board has big problem because Main
IC(IC100) have some troubles.
After checking thoroughly all path once again,
You should decide to replace Main Board or not.
Check TU1200.
Can you see the normal signal?
Check the output of TR(Q1201).
Can you see the normal waveform?
Check the output of Main IC(IC100).
Especially you should check
The H,V sync and clock.
Can you see the normal waveform?
YES
YES
NO
Could you measure voltage of TU1200 &
IIC lines?
Are they all normal?
YES
NO
You should check power line
& IIC lines.
YES
You should replace Main Board.
NO
You should decide to replace TR (Q1201) or not.
NO
After checking the Power of Main IC(IC100) you
should decide to replace Main IC or not.
This board has big problem because Main
IC(IC100) have some troubles.
After checking thoroughly all path once again,
You should decide to replace Main Board or not.
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