LG 50PG60 need testing direction

[stickiestring]

Hello everyone, first post here. I'm on a steep learning curve and thank you all for your help and understanding. I acquired this LG 50PG60 being told it "just stopped working". In my haste, having done a Samsung recently with bad caps, I didn't bother to plug it in first and jumped straight to the board assuming the same. Sure enough, 6 bad ones. I replace those and it fires up. For a fleeting moment I almost see a faint image, then it dims to ambient backlight. Every reset after that I just got a brighter backlight for a second or two then it dims. Just to be sure I did indeed have backlight I unplugged upper Y-buffer and verified. Then I plugged in my phone via HDMI to test for sound and the phone just cycled between "HDMI connected" and "HDMI disconnected". So I grabbed a dvd player with A/V connections and played a movie while I cycled through inputs (power light flashes in response to IR, local buttons don't show a flash when pressed) and I suddenly hear pulsing static through the speakers. I continue cycling and the sound doesn't stop. The lights on power board and main board are both green. I then turn off to resest. Now when I turn back on I get 15 flashes then a looping power cycle. Both lights are still green. I've checked every fuse I can find and all are good. I haven't found a post with this particular sequence of events described. Any help in what this might be and where/what I should check next would be greatly appreciated. Thanks again!

[ReeceyBurger123]

Re: LG 50PG60 need testing direction

This is a Plasma it does nit have a backlight, the glow you see is sus boards priming the pixels. Common issue as you said is the Y upper buffer shorting and causing the set to act goofy. What happens when you remove it and power up the set ?

[stickiestring]

Re: LG 50PG60 need testing direction

Thank you for the correction. With both Y's in I get primed pixels and with upper removed I get top half black. Now I'm unable to test the display any further though because I can't get past the new power loop after the pulsing static sound happened. 2 of the bad caps were 10v 3300 uF but the supply store here only had 16v 3300 uF so that's what I put in. The guy there said it doesn't matter, is this true? And considering that it was rejecting my HDMI and that the pulsing static sound wasn't dependent on input, would this indicate the main board? But if so how did I re-aquire a power loop?

[ReeceyBurger123]

Re: LG 50PG60 need testing direction

Yes you can upgrade 10v to 16v. Also I would agree mainboard issue I have had quite a few of them boards with failed Bga solder joints on the main Cpu and when this happens the motherboard causes the Tv to act very odd. My suggestion be to run the test patterns. Look up on google how to run Lg plasma test patterns and let us know what happens when you do this.

[stickiestring]

Re: LG 50PG60 need testing direction

Okay, so I was able to get the patterns to show up but only for the 15 seconds before power loop. I now know that I have a faulty control, but is this also the explanation for the new power issue, or should I be chasing something else on the power board now as well? Thank you for your help!

[dick_barton]

Re: LG 50PG60 need testing direction

If you didn't have the power looping problem to start with then go back to the beginning. Look very carefully at the circuit board where you changed the capacitors and check that you have them in the correct polarity and there are no fresh solder bridges to any pads along side. Secondly reseat all the connectors you had removed and reconnect making certain they are pushed fully home.

[stickiestring]

Re: LG 50PG60 need testing direction

So a bit of a sad ending to this thread, as I've now learned the importance of fully understanding terminology and identifications before buying parts. When speaking of main board, I assumed A/V board, but when searching for how to run test patterns came across an explanation of what I now know is the logic board as "main board". In my haste to get this thing working I then search for the part and come up with "main control board" and purchased, only to realize my error now that the unreturnable item is in the mail. I've been going through much stress in my day job and personal life, and am now seeing the absent logic in my error (no pun intended), given the test results. It was a foolish mistake that I only have myself to blame for. I'm now over $50 in the hole between the new caps and this board + shipping for a TV that actually needs a $130 A/V board and still has a new power loop since the cap replacement that I haven't been able to track down yet. So when it's over I'd have put in all the work for around the same money I could've just bought a working used unit for. Not sure at this point if I'm going to press on or just cut my losses and punt. Nonetheless, I greatly appreciate the replies and knowledge shared here by people much brighter than I. Thanks again.

[ReeceyBurger123]

Re: LG 50PG60 need testing direction

No worries, you will pull through bud keep going ! Let us know what happens in the end

[dick_barton]

Re: LG 50PG60 need testing direction

 only to realize my error now that the unreturnable item is in the mail

Can you put the part back up for sale to recover some of your money spent so far?

[stickiestring]

Re: LG 50PG60 need testing direction

Yes I will put it on eBay and hope for the best. It's a low price item and not commonly faulty. Shopjimmy charges FedEx rates so I can use postal and offer free shipping. I wish my financial situation wasn't so tight and it wouldn't matter. On the upside, I finally had time to do more testing and found that with the main board disconnected from the power supply I can run the test patterns on the logic board without the power cycling issue. So I guess that's the only problem then. Hopefully the person who wants to buy this older LCD Samsung I did caps on will come through this weekend and I'll have my main on the way! Thanks for the encouragement guys! Feeling a lot more optimistic now.

[stickiestring]

Re: LG 50PG60 need testing direction

Ok guys, I'm going to resurrect this thread with what's happened this summer. I finally picked up a used main board, and was able to aquire sound, but still no picture. Just primed pixels. Out of curiosity and confidence I could re sell the parts, I purchased a Y-sus, then Z-sus when that didn't work. With the new Z-sus I actually lost primed pixels all together. I threw the brand new logic board in during all of this just to be sure. So after verifying again that all power supply voltages are correct, what is left to try? Scan drives? Z-buffer? Since I'm still getting primed pixels on top and bottom which I can verify by disconnecting either Y-buffer, it can't be either of those. I'm genuinely stumped, but not ready to punt it just yet. Thank you all for any more input you may have!

P.S. I found a small nick in a ribbon cable where it was pinched from the factory routing under the lower right wall mount bracket, running from the logic board to either an address board or scan drive on the bottom I'm not sure which it is. Could something like this be the culprit? I'm still not fully educated on what role the address boards or scan drives play in picture processing.

[dick_barton]

Re: LG 50PG60 need testing direction

Post a picture. As they say a picture is worth a 1000 words.