LG NP8540 - Portable Function Doesnt Working

3-13
ONE POINT REPAIR GUIDE
5. PORTABLE FUNCTION DOESN’T WORKING
5-1. IC102 (ADC)
5-1-1. Solution
Replace IC102 on main board.
5-1-2. How to troubleshoot (Countermeasure)
1) Check 5.2 VA.
If 5.2 VA is abnormal follow the stage 1-1.
2) Check 3.3 V_S of IC102(Pin4).
If 3.3 V_S is abnormal follow the stage 3-2.
3) If 5.2 VA and 3.3 V_S are OK, check the PTB_DET is HIGH state when potable cable connected. (L100)
If it’s LOW, follow the stage 3-4. (Micom)
4) When you followed above step but It doesn’t work. Check the around parts. (Resistor, Capacitor, Bead).
If still not working, replace the IC102.
5-1-3. Service hint (Any picture / Remark)
< Main board top view >
5.2 VA
5.2 VA
IC102
IC102
3.3 V_S
3.3 V_S
(Pin4)
(Pin4)