LG 42LY750H Service Manual page 20

6. HDMI Video Trouble Shooting guide
Check input signal format.
Is it supported?
Y
Check AC cable for damage
For damage or open conductor
Y
Check JK3301/JK3302
Can you see the normal waveform?
Y
Check HDCP key NVRAM(IC100)
Power & I2C signal
Y
Check the input of MTK(IC105).
Measure waveform at R3314, R3315, R3308, R3309 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.
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Only for training and service purposes
N
Replace JK3301, JK3302.
N
Replace IC100.
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