Panasonic TH-65PF11UK 65" Plasma - Bad Buffer or Something Worse?

[dgross0818]

Hey Everyone, I'm hoping you can help me out in the diagnosing and repair of a Panasonic TH-65PF11UK 65" Professional Plasma Monitor I bought fairly cheap that currently has a vertical black bar on the screen (with some random noise of various colors within that box)

The bar extends from the bottom of the screen to the center (bottom half) and is the exact width of one ribbon cable that connects to a buffer board.

The bottom buffer board that connects to the ribbon is PN: TNPA4625 and the ribbon cable causing the issue is the second one from the left.

I drew a little white box approximately around where the black bar is (the random colors are actually being produced)

I replaced the buffer board earlier today and started the TV, only to hear a pop and smell smoke coming from the new buffer board.

The TV kept running and displayed the same black box + random junk inside the box after the pop occurred (which was as soon as the replays clicked over)

C601 is missing on the new buffer board, however, I'm not certain if that was the pop or not because the burning smell appears to be concentrated closer to the second ribbon connector and a little to the left (where C607, D602, R622 and R623 are) whereas C601 is above the left-most ribbon cable.

It's a huge panel that cost $5000 or so new, however, now I'm stuck as to what I should try next.

I'm not sure if the panel is bad or if something else caused the new board to short out, as the only two connections to other boards are to the central bottom buffer board, and the board that interfaces with all the buffer boards.

It is possible that the capacitor fell off in shipping, as I wasn't looking for damage before I installed the board, or I may have gotten a bad "new" board, however, that it popped and smelled makes me think there are other issues.

The rest of the TV displays an image fine for what it's worth.

-Derek

[tom66]

Re: Panasonic TH-65PF11UK 65" Plasma - Bad Buffer or Something Worse?

Sadly, the panel is dead on this one if you see that.
If the panel is bad, i.e. shorted, it can blow the new C board.

[dgross0818]

Re: Panasonic TH-65PF11UK 65" Plasma - Bad Buffer or Something Worse?

Tom, thank you for your reply :]

That's unfortunate to hear that it's most likely the panel; I was under the impression they are usually the parts not to break (especially in the case of a professional monitor rated for 100,000hours)

Does that mean that the panel has leaked or that there's some sort of internal short?

Maybe I'll drop another $10-15 or so just to confirm I didn't get a bad buffer board, however, it's certainly disappointing knowing that I might not be able to repair this :-/

You don't think it could be the ysus that's shorting the buffer board?

I guess I could always scale the video to only use the good portion of the screen, however, that would probably look odd as 1080 stuff would not be viewable 1:1 leading to fuzziness

[tom66]

Re: Panasonic TH-65PF11UK 65" Plasma - Bad Buffer or Something Worse?

The 100,000 hour life is the life of the actual phosphors -- it has nothing to do with electronic reliability.

The problem on this model is the buffer chips, which are laser-welded to the panel. Unfortunately when these fail the panel is scrap. And it doesn't appear that any other manufacturer has invented a better way of connecting the column drivers (at least one that would not be unrepairable.)

It's not the Y-sus / SC... right now I would consider the parts you could sell it for.

[dgross0818]

Re: Panasonic TH-65PF11UK 65" Plasma - Bad Buffer or Something Worse?

Thanks again :]

So would I be right in thinking that even if there were a way to replace this bad chip, there might still be an issue because there's a reason that stopped working too?

I've heard that this chip is in the ribbon cable that connects the PDP to the C board, is this correct?

I guess I can always pull off all the boards and sell them... will probably still make back more than I paid for it...but I'd rather have a 65in Plasma haha

[tom66]

Re: Panasonic TH-65PF11UK 65" Plasma - Bad Buffer or Something Worse?

You can't replace the chip. It's embedded in the plastic flex, which is laser welded to the panel. Panasonic don't sell replacement ribbons, because you'd need a million-dollar welding machine to re-attach it.

[dgross0818]

Re: Panasonic TH-65PF11UK 65" Plasma - Bad Buffer or Something Worse?

Thanks again for the help Tom, I appreciate you taking the time to share your knowledge here :-)

I took one last look at the TV yesterday and it pretty much confirmed what you thought... the "dead" zone is actually HALF of what is controlled by one ribbon cable which (from what I've read) means it could have never been the buffer board but rather the IC you can't replace :-(

I might still be able to use the display for some stuff, as I can set my desktop background to black and then use a TV tuner / DVD drive and resize the window to fit in the good portion of the display... (still like 55 inches but not real 1080) at least until I can afford a new set (which will probably be LED so I don't have to worry about this again)

Am I right in thinking that when only half of a ribbon cable is black/garbled that the only explanation is either a dirty cable or a bad IC?

[tom66]

Re: Panasonic TH-65PF11UK 65" Plasma - Bad Buffer or Something Worse?

There are two drivers on each half -- one on top, one on bottom. So failures only affect half the screen, usually.

Don't worry, LED TVs have reliability problems too. Number one failure is the LEDs themselves, which are difficult to replace, and stuck vertical lines (like yours), which are panel failures (also affects LCD.)

No panel is perfect!