LG 40LX770H Service Manual page 23

7. Analog RF Audio Trouble Shooting guide
Check RF Cable & Signal
Y
Check TU8900 Pin2 (SIF Output)
Can you see the normal signal?
Y
Check Audio AMP output
L5602,L5603,L5604,L5605
Y
Check IC5600
Y
After checking audio signal line, you should decide to replace item or not.
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You should replace TUNER.
Could you measure voltage of TU8900& IIC lines?
N
Are they all normal?
N
Replace L5602,L5603,L5604,L5605
N
Replace IC5600
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Y
N
You should check power line & IIC lines.
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