50" LG Plasma 50PA5500

[ztu165]

Hi guys, I have this plasma tv that has no picture or sound. I thought the problem was the y sus board because as I was checking some of the voltages on there I got good voltages but as I got closer to where the lower and upper buffers connect I would just get OL flashing rapidly but not a steady voltage. I ordered the y sus board but I still have no image or sound although now I get voltages instead rapidly flashing OL. What I found out though is that with the new y sus board I no longer have the 55V on the Va what I get is that rapidly flashing OL. The VS is perfect at 205V. If I pop back in the old y sus board however the Va returns normally. If I disconnect the y sus from the
Z sus the Va goes missing again. Now I'm guessing the problem is the z sus board. One other thing is that the y sus does not connect directly to the power supply board instead all the voltages are supplied through the z sus board so disconnecting the z sus will also shut down the y sus down completely. What do you guys think? I'm really sorry for not providing any pictures, but unfortunately my daughter broke my camera.

[tom66]

Re: 50" LG Plasma 50PA5500

This is a damn new TV... Less than a year and a half old?

My guess, if not a hardware problem, would be a crack or damage to the screen. Inspect it very carefully for damage around the edges. The slightest chip and it won't work.

[Sevenqi]

Re: 50" LG Plasma 50PA5500

I fixed two of this model tv, it's really cheap make tv, the life is 1 to 2 years. One of the them the owner pushed the front panel harder, but the mental touch the power supply board, the fuse open. but the panel was still not get cracked!

[tom66]

Re: 50" LG Plasma 50PA5500

Lol. Yeah, I don't like this model, built just like the PS43F4xxx and PS43F5xxx from Samsung. As cheap as can be.

[ztu165]

Re: 50" LG Plasma 50PA5500

So are you saying it can be a powers supply issue? What I did notice was that if I have the z sus board connected to the psu the Va voltage isn't there, but if I disconnect the z sus it shows up.

[tom66]

Re: 50" LG Plasma 50PA5500

Where are you measuring Va?

[ztu165]

Re: 50" LG Plasma 50PA5500

On the powere supply. The port were the connection goes to the z sus. If I have the z sus connected to the port on the psu I don't get the Va, but after disconnecting the z sus it does show up as 55V.

[ztu165]

Re: 50" LG Plasma 50PA5500

Where are you measuring Va?

Tom66 all voltages show up except for the 55V Va.

[tom66]

Re: 50" LG Plasma 50PA5500

There's a thin connector coming from the Z-sus to the bottom of the panel. This carries Va. Unplug this... does Va return?
edit: It goes through the Z-sustain into the sub board which goes to the panel. It's a little thin connector at the bottom of the board.

[ztu165]

Re: 50" LG Plasma 50PA5500

There's a thin connector coming from the Z-sus to the bottom of the panel. This carries Va. Unplug this... does Va return?
edit: It goes through the Z-sustain into the sub board which goes to the panel. It's a little thin connector at the bottom of the board.

Tom66 I'm sorry I feel like an idiot for asking this, but is there another name for the sub board? I don't know what that is. Is it the two boards at the bottom of the tv? Sorry I'm still relatively new at this. I know I'm an idiot, but I'm trying.

[tom66]

Re: 50" LG Plasma 50PA5500

See the Z-sus? It connects to a thin board which then goes to the orange panel connectors?
On the very bottom of it there is a thin two-wire cable going down to the bottom of the panel. Disconnect this. Pictures of the chassis would help.

[ztu165]

Re: 50" LG Plasma 50PA5500

See the Z-sus? It connects to a thin board which then goes to the orange panel connectors?
On the very bottom of it there is a thin two-wire cable going down to the bottom of the panel. Disconnect this. Pictures of the chassis would help.

Hi Tom66, I am working on getting a camera so I can get you some pictures, but for now last night not knowing which board you were talking about I decided to disconnect a very flat ribbon cable that goes from the z sus to the logic board and the Va voltage shows up when disconnected. Is this strange? I did try looking for the thin cable from the sub board but all it has at the bottom are a thin connection composed of two thin cables that go from the bottom of the sub board to the X driver. Nothing that goes to the panel.

[tom66]

Re: 50" LG Plasma 50PA5500

The two thin cables going to the X driver is what I mean. The X driver connects to the panel. If you disconnect that and the Va shows up, you may have a defective plasma panel :/. Let's hope not; the X boards themselves can have failures too.

[ztu165]

Re: 50" LG Plasma 50PA5500

The two thin cables going to the X driver is what I mean. The X driver connects to the panel. If you disconnect that and the Va shows up, you may have a defective plasma panel :/. Let's hope not; the X boards themselves can have failures too.

Tom66 what I'm having a hard time understanding is why when I have the new y sus board that same Va voltage isn't there, but when I pop the old y sus board it does show up.

[tom66]

Re: 50" LG Plasma 50PA5500

I can't explain that, other than saying your new Y-sus is probably defective.

The Y-sus and Z-sus do not use the Va voltage. They simply act as convenient connection points to minimise in-chassis wiring. Va travels right to the bottom of the plasma panel, for the X drivers.

[ztu165]

Re: 50" LG Plasma 50PA5500

I can't explain that, other than saying your new Y-sus is probably defective.

The Y-sus and Z-sus do not use the Va voltage. They simply act as convenient connection points to minimise in-chassis wiring. Va travels right to the bottom of the plasma panel, for the X drivers.

Ok Tom66 as soon as I get the camera I will post the pics so you can help me determine if this tv can be saved or thrown out.

[ztu165]

Re: 50" LG Plasma 50PA5500

I can't explain that, other than saying your new Y-sus is probably defective.

The Y-sus and Z-sus do not use the Va voltage. They simply act as convenient connection points to minimise in-chassis wiring. Va travels right to the bottom of the plasma panel, for the X drivers.

Hey Tom66 I got a z sus board for $17 on eBay, I put it on the tv, plugged everything back fired up the TV and it works now. Only problem now is that there is a thin black line going across the top of the screen. Is this a faulty panel or can it be the buffer board?

[tom66]

Re: 50" LG Plasma 50PA5500

Top to bottom, yep, panel's bad. I'll bet that if you put the old board back in, it'll work again. The line was an internal short in the panel driver, and it finally went "bang" and failed, stopping it from loading down Va.

[ztu165]

Re: 50" LG Plasma 50PA5500

Top to bottom, yep, panel's bad. I'll bet that if you put the old board back in, it'll work again. The line was an internal short in the panel driver, and it finally went "bang" and failed, stopping it from loading down Va.

Tom66, I'm sorry I must of confused you, the black line is a horizontal line on top going from one side of the tv to the other side. It's not a vertical line from top to bottom.

[tom66]

Re: 50" LG Plasma 50PA5500

It can still be a panel fault if left to right, though there's a chance that it is instead a loose Y-buffer connection. Remove and reseat the connectors near the line (if there are 6 connectors each drives 1/6th the panel.) Make sure power is off while you do this.