LG DM5360K Service Manual page 26

5. NO SOUND
There is no sound output by DIGITAL AUDIO AMP DAMAGE, repair the set according to the following
guide.
5-1. BY DIGITAL AUDIO AMP DAMAGE (IN ALL FUNCTIONS)
5-1-1. Solution
Please check and replace IC404, IC701 on MAIN board.
5-1-2. How to troubleshoot (Countermeasure)
1) Check FR_P/N, FL_P/N signals from IC404 to IC701 each input function.
- If no signal, check if I2S audio signals are entered to IC404.
2) Check PVDD.
- If PVDD is abnormal, check the SMPS.
3) Check +12 V for driving the gate of AMP IC.
a. All the powers are normal, but if +12 V is low, there is possible for AMP IC to be damaged.
b. Remove L701, L702, L703 and L704 one by one.
When removed a inductance, if +12 V is recovered, the IC connected to it was damaged.
c. Replace the IC with a new one.
4) Check the impedance between IC701 OUT_A, OUT_B and GND.
a. If the impedance is 0 Ω, the IC must be damaged.
b. After removing the heat sink, replace it with a new one.
5-1-3. Service hint (Any picture/ Remark)
L701 L701
L702 L702
ONE POINT REPAIR GUIDE
L703 L703
L704 L704
< MAIN board top view >
IC701 IC701
3-9
IC404 IC404