lg 42pc1da on and off power supply problem or ??

[tipat]

i got this set today and it keep power on and off every 2 sec. i notive no vs or va voltage when i unplug all cable on the power supply .the ac detect pin got 5v and drop to 0 when clicking also the main board ave 3-4 green diode and 1 red diode that glow when clicking on the imediately shut off after 2 sec like a infinite cycle.i think the power supply maybe dead or the main board..need advise if you know .

[Alastair E]

Re: lg 42pc1da on and off power supply problem or ??

There are many 3300uF 10V caps on that PSU.....

These go bad and can cause exactly that symptom. As I remember--There's 9 of 'em Change the lot! That should help

[tipat]

Re: lg 42pc1da on and off power supply problem or ??

i ave test all one by one out of circuit,all read good .i test the fet and ifound 1 short, replace it ,still no go ...my ac detect pin fluctuate 0v to 5 volt when clicking cycle.. 3.4v ok the rest got nothing ...

[tipat]

Re: lg 42pc1da on and off power supply problem or ??

it the us model 42pc1da-ub

[Alastair E]

Re: lg 42pc1da on and off power supply problem or ??

'Ah--Ive been having 'fun' with that same set--and its IPM's...

The PSU can be removed from the set, and run on the bench.--Makes life easier to work on.
As I recall, there's a PSU-On pin that needs to be tied to the STBY-5V pin by a 1K resistor, also need to supply the Vs-On pin the same way and the 3.3V-On pin too, so that those supplies become active.

A 100W 240V bulb can be connected to the Vs and Gnd pins--and should light. Voltages can be checked and set.
--This is the way I work on the PSU's of sets,--MUCH easier than messing round with it in the set....

What part of circuit was the dead-mosfet in? Maybe you have other dead devices in the drive circuit to that part....

[tipat]

Re: lg 42pc1da on and off power supply problem or ??

the part is a rectifier diode b2306 . i buy a board for 60$ on eBay so i will see if the psu is the problem

[tipat]

Re: lg 42pc1da on and off power supply problem or ??

after replacing the power supply tv turn on but i see red pixelisation on dark area anybody know what board can cause this ..i check the voltage and it all good

[Alastair E]

Re: lg 42pc1da on and off power supply problem or ??

The red spots called, 'Mal-Discharge' are a known issue.

The Control-Board Firmware needs updating using a LG jig and computer with the special software to re-new the firmware with a later version to fix this problem.

'Capkid' in the USA can do this for you as well as myself as we have the jig and firmware-files etc, but I'm based in UK.

[tipat]

Re: lg 42pc1da on and off power supply problem or ??

if i put a new(use) board .how many chance this can work??