Lg plasma tv no video has sound

[anthonyngan]

Re: Lg plasma tv no video has sound

Hi guys here's an update on what's going on with my LG plasma TV.
I tried to resolder new ipms on my original y sustain board. however I still had a short on this particular board; Vs to ground short. I had a hard time finding where that short was coming from. So I decided to order a new y sustain board.

I received it today. I Connected the board but I still have to same problem. I only get voltage out of the power supply board when the p2 connector on the y sus is unplugged see picture. So I tested this new board but But there is no short at all.
So I guess the problem is not coming from my y sustain board. I also tried to disconnect the buffer boards from the y sus But it makes no difference. I'm really at loss here. Can something else have an influence? I'm starting to wonder if there is a problem with the control boards. There is this small connector P1 which I didn't try to disconnect him but I'm afraid that this might cause further problems. Any help would be greatly appreciated.

Power board and z sus:

[anthonyngan]

Re: Lg plasma tv no video has sound

New y sustain board

[anthonyngan]

Re: Lg plasma tv no video has sound

P2 the one that needs to be disconnected in order to get dc voltage out of the PS.

[anthonyngan]

Re: Lg plasma tv no video has sound

Buffer, y and control boards.

[tom66]

Re: Lg plasma tv no video has sound

Have you tried without Z-sustain connected?

[anthonyngan]

Re: Lg plasma tv no video has sound

Hi Tom, thanks again for your help.

Yes I tried that already. The only way to get for voltage out of the power supply is to disconnect this P2 connector.

[anthonyngan]

Re: Lg plasma tv no video has sound

Is it possible that there something wrong with the power supply? As if something goes wrong when voltage is suck out of it. Maybe bad capacitors?

[tom66]

Re: Lg plasma tv no video has sound

Well, it sounds like both of your boards have a short circuit. You could try with a 230V light bulb across Vs to see if you can get it to drive one of those, if it can't, it could be the PSU at fault.

[anthonyngan]

Re: Lg plasma tv no video has sound

Hi again I would really appreciate your help. I don't want to give up on this puzzle.

I didn't try to do the bulb tests which you were suggesting. Since there was a VS to ground short on the power supply board I decided to buy another one from this online shop LCD parts from UK. I Just plugged it in. I really thought that it could solve the case this time.

Unfortunately i have the same problem again...

No Vs va or vy voltage coming out of the power supply board when P2 connector on y sustain board is connected.

I even unplugged every connector that was going out from the power supply board Except for that p2 connector. There is no difference I only get voltage out of the supply board when this connector is unplugged.

I tried to isolate the y sustain board by unplugging to buffer boards but it didn't make any difference.

I could use some live help (Skype, FaceTime ...)

Thanks!

P.S. I won't give up !

[anthonyngan]

Re: Lg plasma tv no video has sound

Hi again,
I'm starting to believe that the y sustain board I received is defective. However there is no short to ground on that board. This question might seem silly But is it possible that the board is defective without having any short to grounds?

[tom66]

Re: Lg plasma tv no video has sound

Yes it is quite possible, we have seen it several times before.

It could be one of the FETs in the IPM is short, and only when the other part of the IPM tries to turn on, does it go wrong.

You could experiment with the control connector disconnected - the flex rigid cable going to the control board in the centre of the screen. That way the FET may be off, but the Y-sus is still powered. Then see if Vsus is still zero.

[anthonyngan]

Re: Lg plasma tv no video has sound

By the way I just found this very nice article about power supply boards of plasma TV

http://www.bestelectronicarticles.co...eshooting.html

It helped me understand that the problem is really Coming from my Y sustain board.

Just wanted to share the link in case it might help somebody

[anthonyngan]

Re: Lg plasma tv no video has sound

I'm very happy to say that I'm making some progress here!

Thanks to the help of Tom and all other posts I found here I was able to get an image out of my TV! The image is not perfect yet a lot of flashing and flickering but and I'm positive I'll find the help I need to resolve the problem.

Here's a quick recap of what I did.

Got this TV for free LG plasma 42 inches mu-42pz15.
It's a commercial model and I really wanted to fix that TV instead of letting it go to the dump.

I found that y sustain board was at fault cause every time I unplugged the connector to that board I would get voltage out of the power supply.
I ordered IPMs from China, Replace them on the board but it didn't work. So I ordered a new board. Unfortunately the board was defective. So I thought that the power supply was at fault so I ordered a new power supply. It didn't solve my problem so at last I replaced again the IPM on the my y sus board and it worked!

Now I think I'm facing the last obstacle to successfully repair the TV.
The image is flickering and flashing I'm going to try to adjust voltage but I'm really not sure what to do with this problem.

Again any suggestions is welcome!

[tom66]

Re: Lg plasma tv no video has sound

Try without upper or lower buffers installed (one removed.)
Could also be dodgy Vs.
Or bad control board.
http://www.youtube.com/watch?v=rEVs6...feature=relmfu
http://www.youtube.com/watch?v=UAzsasx8od8

[anthonyngan]

Re: Lg plasma tv no video has sound

Success!

Turned out a connector on that the main was not properly connected.
Tv is now working and the whole family is enjoying!

Thanks for the help.

[tom66]

Re: Lg plasma tv no video has sound

Glad you fixed it!

[santoshpradhan]

Re: Lg plasma tv no video has sound

first of thanks ,
i had a problem with lg flat crt tv comes beeps sound during power no sound and no display