LG 50PV400 black vertical lines and twin sections

[ponchorage]

I just picked up this set for my first attempt at TV repair. The guy I bought it from said he thought one of the x boards needed to be replaced. It's got a several inch section of black vertical lines with a couple of gray lines interspersed that start at the bottom but don't go all the way up and they flicker. To the right of that, and this is strange, there are dual vertical sections. It's like a small slice of the screen gets repeated. The pictures I've attached will explain it better than I have.

From my research it seems it could be a bad tape carrier package but I'm really hoping it is just an x board gone bad. Any tips on figuring out what is really going on here?

[tom66]

Re: LG 50PV400 black vertical lines and twin sections

Find the control board, it's a little green board usually just below the power board, and upload a picture of it. There is a test that can be done on it.

[ponchorage]

Re: LG 50PV400 black vertical lines and twin sections

Here is the photo of the control board. Looks like somebody had already removed the tape over one of the ribbon cables. Thanks for your help!

[tom66]

Re: LG 50PV400 black vertical lines and twin sections

Ok, above "LGE PDP 101019" there are two holes near "R51" and "R52". Place a wire jumper across these, and disconnect the largest right hand ribbon cable. When you plug in the TV, do you get cycling test patterns? Is all the screen working or is that area still dead?

[ponchorage]

Re: LG 50PV400 black vertical lines and twin sections

Please forgive my ignorance as I've never done anything like this before. Would it be ok to just use a short length of copper electrical wire for this? I don't need to solder anything since this is temporary, right?

[tom66]

Re: LG 50PV400 black vertical lines and twin sections

Yes, just needs to be a little wire jumper, not permanent, you will remove it after test is done.

[ponchorage]

Re: LG 50PV400 black vertical lines and twin sections

I got the cycling test patterns. That area of the screen was still dead.

[ponchorage]

Re: LG 50PV400 black vertical lines and twin sections

Only if it was jumpered correctly would it do the cycling test, right? So does this mean the panel is bad or do I need to check something else?

[ponchorage]

Re: LG 50PV400 black vertical lines and twin sections

I tried it without the jumper and didn't get the cycling test so I assume that worked. Could there still be a problem with another component?

[tom66]

Re: LG 50PV400 black vertical lines and twin sections

Personally I think it's the panel, but maybe you can replace the XL/XC/XR-buffer boards, they are usually cheap. Maybe worth the risk?

[ponchorage]

Re: LG 50PV400 black vertical lines and twin sections

Yeah, it's only like $30 for those on eBay so I'll probably give it a shot if you think it's still a possibility it could be those boards. Thanks again for all your help tom66!

[tom66]

Re: LG 50PV400 black vertical lines and twin sections

Just a note, only replace the board corresponding to the right section. Each board is immediately below the area it controls.

[ponchorage]

Re: LG 50PV400 black vertical lines and twin sections

OK, so looking at the TV from the front (viewing the screen), it is the right side that has the problem. So, I should replace the board on the left side, looking at it from the back, correct?

[tom66]

Re: LG 50PV400 black vertical lines and twin sections

Follow the fault down. It will be controlled by one of the boards. Sometimes there are one, two or three boards. One or two is easy. Three is harder.

[ponchorage]

Re: LG 50PV400 black vertical lines and twin sections

So, I replaced the board and I still have the same issue. Is it possible that the control board is bad or is it the panel for sure now?

[Shinju]

Re: LG 50PV400 black vertical lines and twin sections

tagging myself in this thread, curious as to why your test patterns are not showing up and your outcome.

[tom66]

Re: LG 50PV400 black vertical lines and twin sections

You can try the control board but I would be surprised myself. I don't see it causing the fault. Most likely it's the panel, unfortunately.

[ponchorage]

Re: LG 50PV400 black vertical lines and twin sections

tagging myself in this thread, curious as to why your test patterns are not showing up and your outcome.

The test patterns come up just fine when I use the jumper. I just happen to also still see the black vertical lines. Are you thinking I shouldn't see those while using the jumper?

My outcome so far is the same as when I started - seeing the black vertical lines.

I'm tempted to order the control board if there is any possibility that it is the cause of the problem.

Is there not a more systematic way to eliminate components as being the problem with these LG sets? I've seen that type of breakdown in the Panasonic service manuals where they walk you through how to detect which component is causing the problem.

[Shinju]

Re: LG 50PV400 black vertical lines and twin sections

Sorry, I miss read. From what I understand these test patterns by pass all processing. I am not sure how they work as my 60PV450 has both a blown Y and X board but they were still able to produce a test patten (the image quality was shite) but I was able to see them full screen.

After my probe slip on testing voltages on the Ymain, now I cannot get them to come up at all and when I turn on the panel no test pattern jumper all I get is a quick top half of the screen flash and shut down, MB and audio still active.

Just curious since you have the PV line too to see what your findings and outcome will be.

[ponchorage]

Re: LG 50PV400 black vertical lines and twin sections

Found a control board for $10 on eBay. Worth a try. Feel like I'm shooting in the dark.