50 inch Plasma, bottom half blank, lines in the middle

[keats11]

I have a Insignia Plasma NS-PDP50, which I picked up from ebay, near by.

Basically, when you turn it on, the top half is mostly fine. There are a few horizontal lines across the screen, right in the middle. The bottom half is blank.

Thinking that this is a buffer board issue, pulled the buffer boards and found no shorts. I also had a spare Buffer board lying around, which I installed out of curiosity, and the problems remained the same. From measuring the resistance from the top to bottom buffer board inputs, I see these as a short, in other words, they both get fed the same signal. So I am puzzled at this point as to what could be causing this issue. I have taken some pictures for you to see. Can anyone help?

PS: This panel is shared by several other models: LG50PC*, Sanyo DP50747, Vizio P50HDTV, Zenith 50PC3* etc.

[tom66]

Re: 50 inch Plasma, bottom half blank, lines in the middle

It's probably a buffer board issue, but if the fault remained with the new board, it's not impossible that the panel has caused the fault. That being said, I've never heard of it on these models. Have you confirmed the replacement board was working?

[keats11]

Re: 50 inch Plasma, bottom half blank, lines in the middle

Tom: The replacement board was from another TV I have had in the past, probably an LG, but the same panel. Since there are no shorts in the BB, I am puzzled how the buffer boards could be bad. Also, if the upper buffer board is bad, wouldn't I expect to see a picture on the lower half?

[tom66]

Re: 50 inch Plasma, bottom half blank, lines in the middle

The buffer boards are the only boards which control the picture in the vertical axis.

A chip can be bad on a buffer, which can cause no picture, or it can cause particular parts of the image to fail, which is what has happened in your case. It can be short or open, usually short failures occur but open circuit failures can too apparently.

The one dead line makes me think shorted panel (damaging that one output), and the white area is due to the IC being "wounded" by the nearby failure.

I'm not certain but the fact that you swapped two boards in is only pointing more to the panel. Sorry... Could be a worn ribbon, touching panel edge or something, so check that first.

There is no other board that can cause such a specific fault.

[tw2005]

Re: 50 inch Plasma, bottom half blank, lines in the middle

If you have a another known good upper board laying around, I'd try that. You can see DATA_IN test point as it enters the first buffer IC and daisy chains in and out of those and exits the last one for DATA_OUT for the lower board.

I'm thinking from the display the last IC has failed on the top board and stopped the data from being passed on to the bottom board.

[keats11]

Re: 50 inch Plasma, bottom half blank, lines in the middle

After talking to you guys, I took a look at the buffer boards themselves. I looks like the numbers do not exactly match what they have listed on ShopJimmy. So it is possible that the people tried to change the buffer boards themselves, swapped them for the wrong boards which is why the TV is acting like this. I have ordered the replacement boards from ebay. Will post again once I receive the boards and test them out. Thanks to all.

[keats11]

Re: 50 inch Plasma, bottom half blank, lines in the middle

Just to bring this to a closure, I was able to get the exact boards for the Insignia (they looked exactly like the ones that were in there, and the part numbers did not match, which makes me wonder if the previous owner had tried to replace it with the wrong board) and it worked. The set turned off after only 2 minutes, but then I noticed the fan was not connected. Upon hooking up the fan, everything now works. Glad I asked on here, I was pretty sure the panel had a short, based on the picture and my belief that the buffer boards were good.

[tom66]

Re: 50 inch Plasma, bottom half blank, lines in the middle

So you had two buffers with the exact same failure? Once in a lifetime fault that is...

[keats11]

Re: 50 inch Plasma, bottom half blank, lines in the middle

No no. let me explain this in chronological order. I got this TV from someone, knowing it had some kind of fault. WHen I bought it home and turned it on, it looked like the picture I posted. Then I remembered, I possibly had buffers boards that looked like these from another TV I fixed a while ago, so I put that in and it looked the same as the picture I posted also. That is when I posted on here to see if this could be a panel issue. Little did I know that the people whom from I bought, might have tried to fix it, with the same buffer boards that I had spares of. These buffer boards strangely enough produces the picture I posted. I ordered the correct boards from ebay and it came back up full screen. Really strange!

[tom66]

Re: 50 inch Plasma, bottom half blank, lines in the middle

So... What I'm trying to understand is two separate sets of buffers gave the SAME picture fault down to that bar with that pixel line? You should buy a lottery ticket. Well maybe just bet on a horse. 1/768 chance of that happening.