Panasonic TC-P50ST50 5" vertical black bar

[stupidPanny]

Re: Panasonic TC-P50ST50 5" vertical black bar

Well I tried a set of replacement C boards. The problem was far worse (more sections not displaying), so I had the company send me another set with basically the same results.

Suggestions?

[tw2005]

Re: Panasonic TC-P50ST50 5" vertical black bar

So what step would you recommend next? And I haven't said it enough, thanks for all the help

The million dollar question.

My gut tells me it's probably not A board. If i was working on this, double check all ribbons are seated correctly including the ones going to the C board in question. I'd inspect the contacts of the white ribbons in case there was corrosion or poor contact. Possibly with something non conductive flex the c board or apply pressure to the tiny 20 pin octal buffer ICs on that board, inspect them maybe for dud solder joints (magnifier), maybe warm them up or try freeze spray on them but not while it's running.

Try replacing the c board/s but for all I know it could be the panel but you said it was intermittently working at some stage. I would have expected failing ICs on the panel ribbons would be a more gradual decay of the picture with noisey lines not complete loss of data in one hit and it's not just one ribbon but 2 or 3 by what you have described.

For me that poses the question of the likelihood of all of those dying at the same time. I could understand that if a portion of the Octal buffer failed assuming that has something to do with the data sent to those ribbbons.

It's not an area of knowledge I posess but for what it's worth that's what i'm thinking.

Given the worth of the TV I would spend $30 for some C boards at the chance the panel is good, I could not justify an A board but I sent you a link for some real cheap bits.

at the end of the day you're not having to pay a workshop to diagnose this so you're already miles ahead $$ wise.

I know if this was mine in Australia I'd be challenging Panasonic to fix it out of wty if I had receipts and was the original purchaser.

Someone advanced with an oscilloscope may be able to prove whether the signals are actually being delivered to the panel ribbons. If they were mising at least it may be possible to trace back to where they disappear.

[stupidPanny]

Re: Panasonic TC-P50ST50 5" vertical black bar

So what step would you recommend next? And I haven't said it enough, thanks for all the help

[tw2005]

Re: Panasonic TC-P50ST50 5" vertical black bar

Little does anyone know, I'm actually working for Panasonic trying to stop people buying Samsung and LG panels as replacements .

great, now i know where to get parts at cost

[tom66]

Re: Panasonic TC-P50ST50 5" vertical black bar

Little does anyone know, I'm actually working for Panasonic trying to stop people buying Samsung and LG panels as replacements .

[Frank3y3]

Re: Panasonic TC-P50ST50 5" vertical black bar

God Damn, i'm a begin to suspect Tom and Tw works as FBI Panasonic technicians. These guys are very helpful at giving inputs where to go, what to inspect and what to try. Thumbs up !

[stupidPanny]

Re: Panasonic TC-P50ST50 5" vertical black bar

Alright, finally had a chance to try this out and wasn't able to really achieve much. The bar is fairly hard to predict, so i couldn't really tell when I was accomplishing anything.

Any other suggestions, or is it worth replacing both A and C boards at this point?

[tom66]

Re: Panasonic TC-P50ST50 5" vertical black bar

One thing you could try doing is getting a hairdryer out and start heating up parts. As the set warms up something is expanding and losing contact, or otherwise failing to work, and heat will make this happen quicker. Just be sure not to get it too hot, about 30 seconds in an area should be enough to narrow down a particular part.

The fact that the bar doesn't move doesn't rule out all possible A board faults. If it did move, it would be a certain A board fault.

[stupidPanny]

Re: Panasonic TC-P50ST50 5" vertical black bar

Ah, that worked. I think the only input it doesn't work for is USB, which is what I was using.

The black bar remained in place, so I have to assume this is likely the C boards?

Also, does the fact that it is only flashes up indicate something else? The flashing is tempermental. It seems to be rare when the TV starts up, then get progressively worse for a few hours. If you let the TV on for 12+ hours, it becomes more rare.

[tom66]

Re: Panasonic TC-P50ST50 5" vertical black bar

It should be on whatever input last. You can turn it off first, set an input up (e.g. HDMI or onboard tuner) then turn it on again with that input still connected, it will boot up into service mode like that. At least, that is how it has worked on the older sets, I do not think they have changed it.

[stupidPanny]

Re: Panasonic TC-P50ST50 5" vertical black bar

Okay, made it into the service mode but how do I get a picture to display? It won't let me save the reversed setting, and the background is black so I can't tell if there is a "black bar"

[tw2005]

Re: Panasonic TC-P50ST50 5" vertical black bar

Almost worth a gamble at $30 for a full set of C buffers.

PM sent with links.

Has all parts for yours it appears and seriously cheap!

Hope it's not the panel. If me I'd grab a full set of spares looking at these prices if the panel ends up good. About $220 for a full suite.

Worst case if the panel is shot sell the parts or park it and hope another 50ST50 surfaces with a good panel and blown SC,A etc for sale.

[tom66]

Re: Panasonic TC-P50ST50 5" vertical black bar

Good idea. Didn't think of that.

[tw2005]

Re: Panasonic TC-P50ST50 5" vertical black bar

Yes, you can try reseating those now. However, I suspect that your problem is with either the C(1,2,3) board or A board. Not sure which.

Give the mirror option a go in service mode

"6.2. Option - Mirror
Picture can be reversed left and right or up and down.
00 : Default (Normal picture is displayed)
01 : Picture is reversed left and right.
02 : Picture is reversed up and down.

If the defective symptom (e.g. Vertical bar or Horizontal bar) is moved by selection of this mirror, the possible cause is in
A-board"

[tom66]

Re: Panasonic TC-P50ST50 5" vertical black bar

Yes, you can try reseating those now. However, I suspect that your problem is with either the C(1,2,3) board or A board. Not sure which.

[stupidPanny]

Re: Panasonic TC-P50ST50 5" vertical black bar

Nothing, but I can't easily get to the connectors on the bottom from the C1/2/3 buffer boards as they wrap around into the screen.

Noticed that the 3 buffer boards have 15 ribbons, which if spaced equally on the screen they would each cover ~2.9". Since the black bar is roughly 9", that might mean 3 consecutive areas are not displaying correctly. Add in that the area that is not showing is ~14.25" from the edge, if everything aligns it would mean the rightmost 3 ribbons from C2 are aligned with the problem area.

[tom66]

Re: Panasonic TC-P50ST50 5" vertical black bar

Try tapping lightly around the connectors on the C board or A board with an insulated screwdriver handle - any difference to the picture?

[stupidPanny]

Re: Panasonic TC-P50ST50 5" vertical black bar

Tried it, and unfortunately a no-go. What's the next idea?

[tom66]

Re: Panasonic TC-P50ST50 5" vertical black bar

Yes, those ribbons would be my first check point.

You can operate the TV without the case on, just do not touch any part as it could present an electrocution hazard. Plasma display use 200 volts for panel sustain and 350 volts for panel initialise, so that presents a shock hazard...

[stupidPanny]

Re: Panasonic TC-P50ST50 5" vertical black bar

Would you suggest that I just adjust those ribbons to start with? Also, how dangerous is it to turn the TV back on without replacing the back casing?