Read LG 42LT777H (CHASSIS:LA2FZ) Service Manual online
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RGB-PC Video Trouble Shooting guide
Analog RF Audio Trouble Shooting guide
Check input signal format.
Is it supported?
Y
Check AC cable for damage
For damage or open conductor
Y
Check JK3603
Can you see the normal waveform?
Y
Check the input of MTK(IC105).
Measure waveform at R323, R324 because it’s more easy to check.
Can you see the normal waveform?
Y
This board has big problem because Main chip (MTK) have some troubles.
After checking thoroughly all path once again, You should decide to replace MTK or not.
Replace JK3603
N
Check RF cable & signal
Check TU8900 Pin2
(SIF output)
Y
Check Audio AMP output
L5402,L5403,L5404,L5405
Y
Check IC5400
Y
Check C352
(SIF signal to IC105)
Replace Tuner
N
Replace L5402,L5403,L5404,L5405
Replace IC5400
N
N
Replace IC105
Y
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