LG Plasma 50" white snow screen flashing

[nike13857]

Hi, I'm new to this forum. I recently purchased a 50" LG Plasma from a friend. The tv is model number 50PX1D. I did a search on this problem and couldn't find an answer.

When I turn the tv on, I can hear the sound from the snow(but cable is plugged in), but the picture is mostly black, with a faint white snow that constantly flashes (fairly quickly). I've done some google searching and am believing it is the X, Y or Z boards possibly? I tried to take a picture, but it's pretty impossible to show the flashing with a still picture.

A little background. I've worked on older tv's and arcade games and know how to solder. I've also checked the capacitors and now show any signs of bulging. I'm at a total loss on where to go next. and guidance would be much appreciated. Thanks!

Nate

[nike13857]

Re: LG Plasma 50" white snow screen flashing

Correction, I plugged a game system into the a/v inputs and I could hear the game coming through the speakers. However, when the cable is hooked up only, I can't hear sounds from a tv show (assuming one is on).

[PlainBill]

Re: LG Plasma 50" white snow screen flashing

It's been said many times, a picture is worth a thousand words. A picture of the screen would be an immense help. By your description it could be one of the buffers, one of the sustain boards, or even possibly the main control board.

The service manual is available here. Also, if you search on other LG plasma TVs on this site you will find links to training manuals for LG plasma TVs.

PlainBill

[nike13857]

Re: LG Plasma 50" white snow screen flashing

Pictures are below. It was tough getting a clear picture. The pictures are what flashes up most of the time. There's a vertical bar that jumps around each time the screen flashes.

[nike13857]

Re: LG Plasma 50" white snow screen flashing

Another Update. There's a clicking sound and buzzing sound coming from the Y-Sustain board. Is this normal? Or could this be the problem?

[crepiduse]

Re: LG Plasma 50" white snow screen flashing

You could have a Logic problem or a Sustain problem. Open up the unit and check for visibly bad caps and post pics of all boards for us to see.

[nike13857]

Re: LG Plasma 50" white snow screen flashing

I opened the unit and inspected the caps. None are leaking or bulging. I tried to take pics, but it doesn't show a whole lot and they aren't the clearest pictures.

Another update, I was able to get a cable channel on the tv. The picture still doesn't show up, but I get full sound.

There is a clicking sound coming from the Y-Sustain board from one of the upper yellow things. There is also a buzzing coming from the bottom of the Y-Sustain board, not sure which item is making the sound.

[PlainBill]

Re: LG Plasma 50" white snow screen flashing

I opened the unit and inspected the caps. None are leaking or bulging. I tried to take pics, but it doesn't show a whole lot and they aren't the clearest pictures.

Another update, I was able to get a cable channel on the tv. The picture still doesn't show up, but I get full sound.

There is a clicking sound coming from the Y-Sustain board from one of the upper yellow things. There is also a buzzing coming from the bottom of the Y-Sustain board, not sure which item is making the sound.

Sounds like a shorted hybrid.

PlainBill

[nike13857]

Re: LG Plasma 50" white snow screen flashing

Is the hybrid the yellow things?

[PlainBill]

Re: LG Plasma 50" white snow screen flashing

Is the hybrid the yellow things?

I have never seen a yellow hybrid, on the other hand I have never seen this model of TV. On the other hand, I have never seen anything inside a TV that I would refer to as 'the yellow things'.

There are two possible ways to proceed. The first is for you to follow these steps:

Step 1. Take good, clear pictures of the back of the TV. Try for a resolution as close to 2000 x 2000 as possible.

Step 2. Load the picture into a picture editing software such as Microsoft Paint.

Step 3. Indicate the source of the noise by circling it, drawing and arrow, or similar method.

Step 4. Attach the picture to your next post.

The second is very simple: List the TV on your local Craigslist, Freecycle, etc and give it to someone who has or can borrow a camera, or who has the knowledge to fix the TV.

PlainBill

[nike13857]

Re: LG Plasma 50" white snow screen flashing

I'm not sure what a hybrid is. I meant to say the red things, not yellow.

I've never worked on plasma tvs, but I do know about regular capacitors and resisters, not all this other stuff. I'm determined to fix this tv.

The first picture is on the board in the center of the tv.
The second picture is the Y-Sustain board that I have been referring to.

[Th3_uN1Qu3]

Re: LG Plasma 50" white snow screen flashing

The yellow things are transformers. The hybrid ICs are going to be under one of those heatsinks. I'm unsure of what that little transformer you circled though, but buzzing sounds are almost always signs of a a power supply in protection mode. Something is shorted there.

[nike13857]

Re: LG Plasma 50" white snow screen flashing

Would it be best to just replace the Y-Sustain board? It seems like that's where the problem is coming from, from what I can research. It's a $150 part, so I don't want to invest in it unless it's needed.

[PlainBill]

Re: LG Plasma 50" white snow screen flashing

I'm not sure what a hybrid is. I meant to say the red things, not yellow.

I've never worked on plasma tvs, but I do know about regular capacitors and resisters, not all this other stuff. I'm determined to fix this tv.

The first picture is on the board in the center of the tv.
The second picture is the Y-Sustain board that I have been referring to.

Good work on the pictures. For future reference, please use 'Manage Attachments' (below the text entry form on the 'Reply to Thread' page).

Picture 1 is of the main power supply. The dark marks on the transformers is dried varnish and it's entirely normal. One of the final stages of manufacturing transformers involves sealing them in a large pot, pulling a vacuum on it, then filling the pot with varnish.

Second picture. The brown components are capacitors. The area of the buzzing contains two modules which produce the scan voltages (I think, I'm not familiar with this plasma panel).

The problem I'm having at this point is I'm not sure what the cause is. Ordinarily I would say 'replace the Y-Sustain and the Y buffer', but I can't explain the vertical bar as a problem with the Y-Sustain. If anything I would suspect the main control card (just to the right of the Y-sustain in the second picture). On the back of the plasma panel there are usually several white labels. One lists the voltages, another lists the model number of the panel. Can you identify them?

PlainBill

[nike13857]

Re: LG Plasma 50" white snow screen flashing

The two labels are below.

1st Label:

Model: PDP50x3###
Total Max Watt 500W
Max Volt 5.25V/61Va/200Vs
Max Amps 4.0A/2.2A/2.0A


2nd Label:

All Voltage DC (=) 5V
Va: 60V Vs: 194V
115/-200/115/N.A/95
Max Watt: 400W (Full White)

[PlainBill]

Re: LG Plasma 50" white snow screen flashing

The two labels are below.

1st Label:

Model: PDP50x3###
Total Max Watt 500W
Max Volt 5.25V/61Va/200Vs
Max Amps 4.0A/2.2A/2.0A


2nd Label:

All Voltage DC (=) 5V
Va: 60V Vs: 194V
115/-200/115/N.A/95
Max Watt: 400W (Full White)

Great - PDP50x3 panel.

The PIONEER PDP503CMX PLASMA TV TRAINING MANUAL available on www.elektrotanya.com gives an explanation of the operation of this panel. It includes a block diagram of the Y-sustain.

The LG Electonics Quick Reference Alignment Hand Book is another source.

HOWEVER, the holy grail (in this case) is the 7580885 LG TV Plasma training manual. This manual covers your panel in detail, including information on identifying the cause of various problems.

PlainBill

[rayrod81]

Re: LG Plasma 50" white snow screen flashing

This is my first post and may be a little long-winded but bear with me.

Not sure if you figured out your problem yet but this may help. I have had 3 plasmas come to me in the last couple of weeks with the flashing problem. 2 were the LG 42x3 panel and 1 was a 50x3 panel. The problems were all caused by the Y-Sustain boards. In fact, it is one of the IPMs. They may test ok in the board and not have any shorts but they are the problem.

The 50x3 had a shorted FET on one of the buffers so initially I replaced the FET and I had a great picture. I let it stay on for a couple of hours to test it and the picture started flashing intermittently, then non-stop after 2 more hours and finally it blew a FET on one of the buffers again. What was weird is that it would only make one buffer go bad. After replacing the bad FET on the buffer again I put it back on the panel and the same thing happened. Luckily, I had an extra Y-Sustain for the 50x3 and put that in the panel with the original buffers and sure enough it worked and never quit. I took the IPMs out of the old board and sure enough one of the transistors was starting to go bad. It was hard to see without a magnifying glass but it was there.

Now on to the 42x3 panels. They had the same problem and the IPMs seemed fine. I decided to replace the IPMs on both boards mainly because it was much cheaper than buying two new Y-Sustain boards. I am happy to say that the IPMs were the cause of the problem. Like I said both tested good but both had one transistor that was starting to go bad just like the IPMs from the 50x3 Y-sustain.

I hope that helps you fix your problem if you haven't already. Be sure to check the FETs on your buffers because they may or may not be bad.

[colorless]

Re: LG Plasma 50" white snow screen flashing

Sorry to bring back a old thread but i have the same problem found a bad fet on the buffer board and replaced it only now to have the tv flash on and off with white snow, I tried to remove the buffer board that had the bad fet but the problem stayed, I suspect the y sus board has a bad ipm but don't want to spend the money on a set if really only one is bad or something else might be causing it?

[colorless]

Re: LG Plasma 50" white snow screen flashing

Sorry forgot to say I pulled the y usu board and applied 5 volts to both ipms and they gave me 16.3v not 18v but I read that this is still ok?