LG LHB976, Service Manual

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2-82
When you turn on your set, it will blank / no message or “PLEASE WAIT” display on front panel,
and it will not boot-up.
1-3-2. IC153 (NO 3.3 V)
1-3-2-1.
Solution
Replace IC153 on MAIN board.
1-3-2-2. How to troubleshoot (Countermeasure)
1) Please check 3.3 V (IC153 Pin3).
2) If 3.3 V voltage doesn’t come out, check IC153 pin2 (Vcc 3.8 VA).
When you figure out those power if there is no 3.8 VA, please check 3.8 VA from SMPS.
For the solution please back to the solution 2.
3) If 3.8 VA input is normal, first of all check the 3.3 V_CTRL is high(IC101 pin58).
if 3.3 V_CTRL is high, check R148, R1C8 and if there’s no defective component then replace IC153.
4) If 3.3 V_CTRL isn’t high, you may need to replace IC101.
5) After changing it, if the set is still not booting:
- Refer to the next page for checking another power source. (1.2 V, 1.5 V)
- Check crystal X500 refer to item 1-3-5.
- Check NAND flash IC (IC506) refer to item 1-3-6.
- Check DDR IC (IC502, IC503) refer to item 1-3-7.
- Check BCM7633 (IC500) refer to item 1-3-8.
* Important : If system is supported Quick Booting Mode,
3.3 V / 1.5 V / 1.2 V Power Vcc is always High. (Standby Mode same).
1-3-2-3. Service hint (Any picture / Remark)
< MAIN board bottom view >
MAIN SET ONE POINT REPAIR GUIDE
IC153