How to repair LDC ! Switch on display come One time

Sumer September 01, 2014

After switch on display come on the panel.

but after few minute no light appear power LED is blowing.

In this case power supply is defective or CCFL is Defective. so first we check power supply for hundred percent ok.

For 100% checking attached with 15watt DC bulb Ground, then power on bulb has been glowing with require voltage available then attached a 12v dc track and check voltage again is bulb and required voltage and 12v ,5v track in power supply is ok.

But after attached bulb secondary voltage drop ,secondary voltage is blinking and bulb is not blowing means power supply is defective, so check secondary filter capacitor and diode and check opto coupler and SCR may be faulty and check triggering voltage is available at STR pin.

If STR (if used) and check low value resistance attached with source to ground in switching power supply and check MFC feedback component in rare case check SM transformer for faulty or used power diode in secondary side .