26LD340H (CHASSIS:LA06F) - LG TV Service Manual (repair manual). Page 53

Audio out Trouble shooting guide

Check the output of Mstar(IC101).
Measure waveform at R503, R504, R505. 
because it’s more easy to check. Can you see the normal signal?

Check the input (Pin 17,18,19) of NTP7100(IC501).
Can you see the normal waveform?

YES

NO

NO

This board has big problem because Main chip (MStar) have some troubles.
After checking thoroughly all path once again, 
You should decide to replace Mstar or not.

After checking audio signal line, you should decide to replace item or not.

YES

Check the output (Pin 30,31,36,37,47,48,53,54) of NTP7100((IC501).
Can you see the normal waveform?

NO

YES

After checking the Power & I2C & Reset of this chip, 
you should decide to replace this or not.

Check the speaker output wafer P501.
Can you see the normal waveform?

NO

YES

After checking audio signal line, you should decide to replace item or not.

Check the connector & Speaker