LG 42LY750H Service Manual page 22

Analog RF Audio Trouble Shooting guide
Check RF cable & signal
Check TU6500 Pin6
(SIF output)
Y
Check Audio AMP output
L5402,L5403,L5404,L5405
Y
Check IC5400
Y
Check C352
(SIF signal to IC105)
Y
Replace IC105
AV / Audio in Trouble Shooting guide
Check input signal format.
Is it supported?
Y
Check AC cable for damage
For damage or open conductor
Y
Check JK3601
Can you see the normal waveform?
Y
Check the input of MTK(IC105).
Measure waveform at C345, C346, C319 because it's more easy to check.
Can you see the normal waveform?
Y
Check Audio AMP output
L5402,L5403,L5404,L5405
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.
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Only for training and service purposes
N
Replace Tuner
N
Replace L5402,L5403,L5404,L5405
N
Replace IC5400
N
Replace JK3601
N
Replace L5402,L5403,L5404,L5405
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