LG 47LT640H Service Manual page 39

Standard Repair Process
LCD TV
symptom
First of all, Check whether all of cables between board is inserted properly or not.
(Main B/D↔ Power B/D, LVDS Cable,Speaker Cable,IR B/D Cable,,,)
No video
Normal
Normal audio
audio
Move to No
video/No audio
※Precaution
☞A7 & A3
Always check & record S/W Version and White
Balance value before replacing the Main Board
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Only for training and service purposes
A. Video error
Error
No video/ Normal audio
☞A1
Y
Check Back Light
On with naked eye
N
☞A2
Check Power Board 24V,12V,3.5V output
☞A4
Y
Check Main Board
On
3.5V,12V,3.3V,
1.26V, 1.5V etc.
N
Replace Inverter
Normal Y
or module
voltage
N
Repair Power
Board or parts
Replace Main Board
1
Established
date
Revised date
Y
Normal
Replace T-con
voltage
Board or module
☞A28
N
Repair Power
Board or parts
End
Re-enter White Balance value
1/13
LGE Internal Use Only