Lg 50pa5500

[davidlan]

Hi All,

I've got a LG 50PA5500. Was watching TV yesterday and the TV just shut off and when I tried turning it back on it cycled through on/off until I simply unplugged it. I've found someone else on this forum who had the same exact issue, and he replaced the PSU board and the TV came back to life.

I've opened up the TV, and carefully looked at the PSU board and it seems to me that one of the caps is bulging. Is this assessment correct based on the pics below? If I replace this cap with a new one do you think the TV has a chance of coming back to life or should I just replace the entire PSU board?

Thanks,
David

[tom66]

Re: Lg 50pa5500

The capacitor appears to be OK.

When you say cycles on and off -- do you hear a relay click from the set?
Does it click continuously or only a few times then stops?
Any sound from the set?

[davidlan]

Re: Lg 50pa5500

Yes, I hear it clicking on and off, and it happens continuously until I unplug it. The clicking is coming directly from the PSU board. No sound.

[football0062]

Re: Lg 50pa5500

came across this earlier today when i was troubleshooting same model tv. exact same problem. i dont know what all you have looked at having not stated and voltage readings or anything but my problem was my VS voltage was way low, like 5 volts(suppose to be over 200V). anyways its a common problem with these power supplies and the feedback capacitor on the primary side of the VS circuit is the culprit. mine was only slightly bulged out on the side. pulled one from another board i had around and fired right up. attached a pic to show you the cap im talking about. good luck

[davidlan]

Re: Lg 50pa5500

Hi football0062,

Thanks for the suggestion, might as well give it a try. I've looked at the capacitor closely and it doesn't appear to be bulged out, but I'll replace it anyway and see if that fixes the problem. If it doesn't then I'll probably just get a working used board on ebay and replace the whole board.

Quick question though: how long should I wait after unplugging the TV to attempt this repair? I've successfully changed capacitors in the past on broken electronics, but they've always been much lower voltage. I want to be cautious as this specific cap has a 1250V rating on it. Should I really wear rubber gloves for safety as I've seen in other forums?

Thanks,
David

[tom66]

Re: Lg 50pa5500

As a quick test, try unplugging that big power connector coming out of the power supply with Va and Vs on it. See if the clicking stops, it could be a shorted sustain board or bad coupling capacitor as football suggests, we have seen them fail a few times.

As for unplugging, 30 minutes is usually sufficient, but it is always a good idea to test before touching - especially around the big 450V capacitors.

[davidlan]

Re: Lg 50pa5500

I've unplugged that big power connector and the clicking just continues. So what does that mean? Faulty PSU board? Could replacing the coupling or feedback capacitor fix this (even though it doesn't appear to be bulging at all)? Or just replacing the entire board is the best bet?

I've carefully inspected all the caps and none appear to be deformed. Is there anyway else I can salvage the board I currently have if replacing that feedback capacitor doesn't fix the issue?

Thanks a lot!
David

[tom66]

Re: Lg 50pa5500

With the board removed could you test the Vs voltage?
Replacing the coupling capacitor ("feedback capacitor") could fix it, but I cannot guarantee anything.

[davidlan]

Re: Lg 50pa5500

Sure, how would I go about testing the Vs voltage? I just picked up a multimeter yesterday.

[tom66]

Re: Lg 50pa5500

Can you post a picture of your meter?

[davidlan]

Re: Lg 50pa5500

Sure, here it is.

[davidlan]

Re: Lg 50pa5500

football0062!

I just got the feedback capacitor that you suggested changing in the mail today. I took out the old one (that, even after taking out, still didn't appear to have any bulge in it at all) and replaced it with the new one from digi-key. The TV powered right up! I'm sitting here watching The Office thanks to you!

Thank you soooo much!

[davidlan]

Re: Lg 50pa5500

And for anyone reading this forum in the future, here's the exact capacitor I ordered from Digi-key (cost me $0.89).

Digi-Key Part Number: 495-1360-ND

B32652A7223J

http://www.digikey.com/product-detai...3J/495-1360-ND

[refnoredcard]

Re: Lg 50pa5500

Dito. Same problem, TV turns on then immediately turns off, an LG 50PA5500, two and a half years old. Sometimes if I left it unplugged for a while and plugged it back in, then it would click at intervals of 1 & 5 seconds repeatedly.

Inspection of the main power board showed C802, a black rectangular film capacitor at the top of the board between the transformer and heatsksink was slightly bulging at the sides. Replaced the part 0.022uF 1.25KVDC, on DigiKey at $0.89 + ~$3 shipping [same part number as davidlan has].

Too bad I didn't find this thread a few weeks ago, but alas, same end result.

[ccsucher]

Re: Lg 50pa5500

Hello everyone, I know this is an old thread. I have the LG 50PA5500 and it is dong just as stated above. Power on will not work and the power LED is lit but the power button does not respond. If you turn the lights off you can see the backlight is on. Unplug and plug back in it clicks screen comes on then off with no response from the power button. I replaced the Digi-Key Part Number: 495-1360-ND and seems to be the same thing. The screen now flashes fine lines. What next?

[tom66]

Re: Lg 50pa5500

Hello everyone, I know this is an old thread. I have the LG 50PA5500 and it is dong just as stated above. Power on will not work and the power LED is lit but the power button does not respond. If you turn the lights off you can see the backlight is on. Unplug and plug back in it clicks screen comes on then off with no response from the power button. I replaced the Digi-Key Part Number: 495-1360-ND and seems to be the same thing. The screen now flashes fine lines. What next?

Please create a new thread. If your "backlight" is on (you have slight panel glow) it's probably the main board, but this can be tested.