lg 50pc1dr

[sum1else]

Hi,

I have this 50 inch LG 50pc1dr that is busted. It has the famed clicking with red/blue led light and then shuts off. There were some bad caps and I do not have a steady enough hand to change them all. I ordered a new board online and installed it today. This did not solve the problem. I've isolated every board and I can't get it to stay on.

I read about the AC Detect issue. There is the one plug connector that has ACD on it. If I remove this one only, the TV goes into a cycle, where it clicks and shuts off and then does it over and over.

So anyway, now I have two boards. I would like to short the AC Detect as Tom66 has advised on other threads, if you think this is a potential solution. I don't have any meters or tools, just a soldering iron. I'm willing to try this out on one of my boards without knowing if its the problem. I can't find a thread where the photos were the exact same power supply, so I need some help figuring out where I need to work.

Since the "new" board is installed, I photographed the old board for sake of convenience. I think I know where the target area is and took some close ups, but I would appreciate confirmation. It would be even better if you could put a line where the solder needs to go. Thanks so much!

These photos are quite large. I can make them smaller if necessary


http://dl.dropbox.com/u/12835111/lgtv1.JPG

http://dl.dropbox.com/u/12835111/lgtv2.JPG

http://dl.dropbox.com/u/12835111/lgtv3.JPG

http://dl.dropbox.com/u/12835111/lgtv4.JPG

[tom66]

Re: lg 50pc1dr

I like to call this PSU (and its cousins) the "Troll PSU" because it had bad caps just like yours, puked everywhere and the classic bad cap symptoms (clicking relay, not wanting to stay on) but replacing the caps didn't fix the problem.

As you have read AC Detect causes issues and on mine it was simply that, so you can imagine how frustrated I was after wasting a month chasing bad capacitors . It seems to be a problem with a lot of other LG TVs, but no one knows about it anywhere else. Strange.

Generally on the xxPCxD series of LG Plasma TVs the symptom is the relays will click, the PSU will buzz, the screen will flicker (but not always), then the relays will click back, and the PSU will restart this cycle. Mine did the rapid clicking when the connector was disconnected, I figure it's not seeing the inputs as stable and getting confused.

I highly recommend even a basic $3 multimeter as can be acquired from Harbor Freight or similar shops. But without it you can still make a test fix.

Your PSU will have optocouplers (the four legged black things that straddle the primary-secondary barrier, with the line between the sides.) Most of these optocouplers send a signal from the secondary to the primary, to control voltage regulation. A few send a signal from primary to secondary -- these are usually your AC detect optocouplers. I think those are the devices in picture 4, but I can't be sure which pair it is, because I'm not sure what the "normal" orientation of them is on your board.

If you find any going the this other way, try placing a bridge between the two pins on the secondary side, just use a small amount of solder and melt it between the pins. Don't bridge anything if you find any more than two, because there might be an important function performed by one of them. Also, bridge the pins of each optocoupler separately; don't connect either optocoupler to its neighbour.

Important: Do not make any connection between primary and secondary - the split is there for safety reasons. Try to avoid excess solder splashing or crossing the boundary.

You've probably read this before but this bodge/fix disables AC detect which is mostly not an issue and usually only causes a "pop" or "click" from the speakers when unplugged while powered on. (But it doesn't affect standby.)

[sum1else]

Re: lg 50pc1dr

Thanks for the super fast response. I didn't realize a multimeter was so cheap. I will grab one for sure.

How exactly can I figure out which two it is? On the non-green side of the board there are clearly markings (indicated by circles) that looks to me like its indicating directionality, I just am not sure which direction it represents. Also, on the green side there are markings as well. I've edited picture #4 (same link) to indicate primary/secondary. Perhaps that's all you need.

How many bridges do I end up making. Two right?

Thanks again.

[tom66]

Re: lg 50pc1dr

You are correct, the dot indicates orientation.

You want to make two bridges, one on each optocoupler.

[sum1else]

Re: lg 50pc1dr

Doh. I did it. The board still clicks but it doesn't click repeatedly. I guess I have bigger problems...

[caprat]

Re: lg 50pc1dr

I recently obtained a LG 50PC1DR myself. I hoped that the three bubbled capacitors I found on the power supply were the only problem. I replaced those today and the TV still has the same problem: The TV makes a clicking sound, flickers at a 2-3x per second pace. The picture is fine when it flickers on and the sound is just fine.

After I replaced the capacitors I noticed the clicking is coming straight from the Y-Sustain and clicks with the flickering. I took tom66's advice and bridged the optocouplers and it did nothing to help. The y-sustain still clicks and the screen still flickers.

Any advice beyond "replace the Y-Sustain board"? Thanks guys.