PANASONIC VT20 RECTANGLE TOP LEFT ISSUE - AVS Forum
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post #1 of 27 Old 03-13-2013, 08:17 PM - Thread Starter
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PANASONIC VT20 RECTANGLE TOP LEFT ISSUE


Has anyone had this issue with this TV? During the summer I just had a rectangle with a lot of redish vertical lines and I haven't had that problem during the winter, until now it came back and I don't have any warranty on it so I was wondering what you guys have done.




Please help
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post #2 of 27 Old 03-14-2013, 07:24 AM
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It could be a failure in the PCB board that drives the upper half of the panel (since the bar only extends down to the half-way point), or it could simply be a loose connector or ribbon cable etc that drives that portion of the panel.

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post #3 of 27 Old 03-15-2013, 06:18 PM - Thread Starter
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Do you know of any websites that sell parts for plasmas?
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post #4 of 27 Old 03-16-2013, 04:40 PM - Thread Starter
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Or does anyone have video on how to take this tv apart just in case?
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post #5 of 27 Old 03-19-2013, 08:27 AM - Thread Starter
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Bump
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post #6 of 27 Old 04-15-2013, 06:31 PM
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I'm having this exact same issue. I'm no electronics wiz, but is there something I can do to troubleshoot this? How I would I go about checking on the PCB board or connector/ribbon cable suggested by Randy? Plese help a first time poster out! Thanks. smile.gif
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post #7 of 27 Old 04-16-2013, 04:56 AM
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It does sound like a loose connector. What is the screen size of the panel? This is important because some older Panasonic plasmas of large screen sizes (60" and above usually) were dual scanned, the top and bottom being treated almost as separate displays for the addressing portion.
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post #8 of 27 Old 04-16-2013, 04:41 PM
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Thanks for the reply. It's a 50" VT25. Only about 2 1/2 years old. Probably been this way for about 6 months or so. Would this http://www.amazon.com/Panasonic-Printed-Circuit-Board-Txnc61Ltuu/dp/B005DNSHFO be the PCB that Randy is referring to?

I almost gave up trying to find a service manual on-line (free!) but came across one late last night here http://elektrotanya.com/panasonic_tcp50vt25_tcp50vt20_chassis_gpf13du.pdf/download.html . The manual identifies the board in the top left as a C6-Board TXNC61LTUU.

I also found some YouTube videos which seem to be related in nature, including this one http://www.youtube.com/watch?v=Zg9dF1ZYNUc . It talks about the ribbon cable connector being a cause of a similar problem about 2-3 minutes into the video.
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post #9 of 27 Old 04-17-2013, 12:35 PM
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I don't know all Panny parts off by heart!
You would need to take the cover off and get pictures because Panasonic are fond of changing parts mid-revision and you may end up ordering the wrong one. Part numbers are printed on each of the boards. I doubt you need to replace the part, the connector should be the only issue.
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post #10 of 27 Old 04-17-2013, 08:35 PM
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Whaaat? I guess if you did, then you'd be Pro TV tech!! wink.gif While this appears to be a relatively simple operation, this will be my first time venturing into the innards of my TV. Other than unplugging the power, any other words of wisdom for this Noob TV tech-wanna-be?
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post #11 of 27 Old 04-18-2013, 12:04 PM
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Wait half an hour after unplugging before getting the cover off. Don't be tired around the high voltage that permeates almost all consumer electronics like this. Bag all screws by size and memorise or write down locations. Take good clear pictures using the best camera you can: avoid flash, where possible - diffuse lighting works best.
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post #12 of 27 Old 04-18-2013, 09:09 PM
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Thanks for the tips. I guess waiting a half hour is to let the capacitors dissipate their charge? Will I be able to take the back off the TV with it still upright on the stand or will I have to lay the TV down and remove the stand?
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post #13 of 27 Old 04-19-2013, 11:29 AM
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Also temperature. The TV runs hot and you do not want to burn yourself.

I do not know if you need to take off the stand. On most Panasonic TVs I have serviced you do not. However I've only worked on a G10 as the latest model, as I usually deal with buying faulty sets and refurbishing them.
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post #14 of 27 Old 04-20-2013, 08:23 PM
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It worked! smile.gif

To remove the back there were 34 total screws with 8 different types - great pointer on keeping them sorted seperately. I printed out the page from the sevice manual I found on-line which showed the location and types of all the screws. That was helpful to have. It turns out I was able to leave the TV on its stand. In addition to removing and re-seating the suspect ribbon cable on the the C6 Board, I looked at all the capacitors on all the boards for any signs of bulging or leaking and all looked good. I also detatched and re-seated both ends of the cable from the P Board to the C6 Board. Then I use some compressed air to blow out a bunch of dust. I took a bunch of pictures as you suggested which actually came in handy when re-attaching all the cables from the cable box, blue-ray player, vcr, wii, and playstation.

Thanks so much for all your help!

Here's a pic. The ribbon cable I re-seated was the one in the upper right corner. I was surprised by the metal flexible cable holder which required me to remove two more screws - but it all worked out.

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post #15 of 27 Old 04-21-2013, 12:15 PM
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Excellent to hear! Enjoy the TV. The metal piece is the heatsink for the chip which is embedded on that flex -- it's very important that the screws are secured down, or the chip on that flex can fail, which means the entire plasma panel is scrap.
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post #16 of 27 Old 04-21-2013, 05:04 PM
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Yikes! eek.gif The service manual nor any of the research I did made any mention of these metal pieces' heatsink function. I'm pretty sure I snugged them down tightly.

Just so I'm certain, you're talking about the metal brackets along the top of this pic, right? It's the top right one I detached and re-attached.

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post #17 of 27 Old 04-23-2013, 04:08 AM
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Hi!
I'm having the same issue for some time now. After some time it just starts "flashing" and then the image becomes ok. Was your syntoms the same?? I'm trying to get some guts to try to repair it myself. Could you please post some more pictures with the cable highlighted??!!!
My tv is a 50" VT20.
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post #18 of 27 Old 04-23-2013, 04:52 PM
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Yes -- that metal piece secured down with two screws. The chip is bonded to it (glued using thermal adhesive.) The ribbon is attached to the IC. (I think the ribbon and chip is attached to the heatsink as a whole.) The ribbon is also bonded between the two layers of glass in the panel, making it unreplacable if it fails -- this is by necessity due to the high connection density. Clamping down the screws ensures the IC receives proper heatsinking and prevents failure. Some panels have thermal pads on the other side. Failure of said IC leads to vertical lines, black bars, etc. The ICs operate at around 60V, with 384 channels each -- the semiconductor design for that is not trivial in one bit and they do run quite hot.

@xpto56 the ribbon is one of those metal clamps along the top or bottom X board, WITH POWER OFF disconnect the ribbon and reseat it then turn it on to test. Each ribbon drives the appropriate portion of the display panel (PDP.)
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post #19 of 27 Old 04-23-2013, 09:27 PM
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@tom669 - Yep. When I lifted the metal piece, the ribbon was attached. If I knew in advance that this was how it was constructed, I either would have been too chicken to remove the metal piece or would have looked at the underside and maybe taken a picture. But the only way I was really going to be able to re-seat the ribbon under the plastic clip was to remove the metal piece and gently push the ribbon down.

@xpt56 - I never had any "flashing". The "rectangle" would sometimes seem to disappear for a while but would always come back. When looking closely at the TV, there were thin vertical lines. From normal viewing distance this appeared as a discolored rectangular area similar to the picture in the 1st post. In the below picture, I circled the metal bracket that I removed (2 screws) as well as the plastic clip which hinges up to release the ribbon. Here's a video that shows how a similar ribbon cable is removed and re-seated https://www.youtube.com/watch?v=lKx-bDyCSoI . He removes the ribbon about 2 minutes in and re-seats it later.

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post #20 of 27 Old 04-29-2013, 05:19 AM
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Quote:
Originally Posted by bruucee View Post

@tom669 - Yep. When I lifted the metal piece, the ribbon was attached. If I knew in advance that this was how it was constructed, I either would have been too chicken to remove the metal piece or would have looked at the underside and maybe taken a picture. But the only way I was really going to be able to re-seat the ribbon under the plastic clip was to remove the metal piece and gently push the ribbon down.

@xpt56 - I never had any "flashing". The "rectangle" would sometimes seem to disappear for a while but would always come back. When looking closely at the TV, there were thin vertical lines. From normal viewing distance this appeared as a discolored rectangular area similar to the picture in the 1st post. In the below picture, I circled the metal bracket that I removed (2 screws) as well as the plastic clip which hinges up to release the ribbon. Here's a video that shows how a similar ribbon cable is removed and re-seated https://www.youtube.com/watch?v=lKx-bDyCSoI . He removes the ribbon about 2 minutes in and re-seats it later.
Quote:
Originally Posted by bruucee View Post

@tom669 - Yep. When I lifted the metal piece, the ribbon was attached. If I knew in advance that this was how it was constructed, I either would have been too chicken to remove the metal piece or would have looked at the underside and maybe taken a picture. But the only way I was really going to be able to re-seat the ribbon under the plastic clip was to remove the metal piece and gently push the ribbon down.

@xpt56 - I never had any "flashing". The "rectangle" would sometimes seem to disappear for a while but would always come back. When looking closely at the TV, there were thin vertical lines. From normal viewing distance this appeared as a discolored rectangular area similar to the picture in the 1st post. In the below picture, I circled the metal bracket that I removed (2 screws) as well as the plastic clip which hinges up to release the ribbon. Here's a video that shows how a similar ribbon cable is removed and re-seated https://www.youtube.com/watch?v=lKx-bDyCSoI . He removes the ribbon about 2 minutes in and re-seats it later.

Thanks for the reply.
I'm just wondering if one can remove and re-seat the ribbon without having to lift the metal piece.
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post #21 of 27 Old 04-29-2013, 12:45 PM
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Possibly, however, it would be best to remove it, to give you more freedom to manipulate it. You leave the metal attached, just unscrew the two screws. Just remember to secure the two screws before powering the set up.
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post #22 of 27 Old 04-29-2013, 08:46 PM
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You could try just lifting the plastic clip and kind of pushing on the ribbon cable, but, as tom said, the metal piece really needs to be removed to pull the ribbon cable fully out of its seat. One of the reasons I did remove the metal piece was that I was concerned that if I applied too much force on the very short length of free ribbon cable to try and move it, I might damage the cable and make myself and my family very sad frown.gif .
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post #23 of 27 Old 05-05-2013, 05:24 AM
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Quote:
Originally Posted by bruucee View Post

It worked! smile.gif

To remove the back there were 34 total screws with 8 different types - great pointer on keeping them sorted seperately. I printed out the page from the sevice manual I found on-line which showed the location and types of all the screws. That was helpful to have. It turns out I was able to leave the TV on its stand. In addition to removing and re-seating the suspect ribbon cable on the the C6 Board, I looked at all the capacitors on all the boards for any signs of bulging or leaking and all looked good. I also detatched and re-seated both ends of the cable from the P Board to the C6 Board. Then I use some compressed air to blow out a bunch of dust. I took a bunch of pictures as you suggested which actually came in handy when re-attaching all the cables from the cable box, blue-ray player, vcr, wii, and playstation.

Thanks so much for all your help!

Here's a pic. The ribbon cable I re-seated was the one in the upper right corner. I was surprised by the metal flexible cable holder which required me to remove two more screws - but it all worked out.


My VT 20 developed the same issue as yours last night. After a few glasses of liquid courage I got up gusto to open the the back panel. I detached and re-seated the same ribbon cable as you did and it solved my problem as well. smile.gifsmile.gifbiggrin.gif

Kudos to Panasonic for using standard Philip head screws everywhere. I was expecting to find a ton of weird sized torx screws.
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post #24 of 27 Old 05-05-2013, 10:30 AM
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Congrats! I was pretty nervous about it at first as well. But after reading up on it, watching some YouTube videos, and with tom669's guidance I got up the nerve. It felt good to fix it myself!
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post #25 of 27 Old 06-25-2013, 07:16 PM
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I just joined the forum in order to thank you all for the helpful pics and advice when dealing with this problem. I carried out the reseating of the offending ribbon today and it worked a treat. The only problem I had which took ages to rectify was two of the screws at the back would not budge and I ended up drilling them out. rolleyes.gif

I could find no obvious fault with the said ribbon ie loose connection etc so I removed the two screws as stated in your advise and reseated it. The TV had a sticker inside made May 2010. The problem had gone from the odd flickering of the offending portion of screen to this week being a permanent annoying feature. Anyway thanks to you guys all well. There was a fair amount of dust around the four fans which I cleaned off with the help of my wife's fluffy make up brush. biggrin.gif
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post #26 of 27 Old 06-21-2014, 08:08 AM
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Worked for me as well, I had the same purple line as in the first post in this thread. I noticed it was missing the color red. Once I reseated the cables in the top the problem was gone. Its a panasonic 55 inch plasma 3d tv. I was going crazy and was all prepared to shell out 1500 for a new one today. Thanks to all the brilliant help in this forum, you saved me a huge amount of money!
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post #27 of 27 Old 06-22-2014, 05:23 AM
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Cool

Quote:
Originally Posted by wthierry View Post
Worked for me as well, I had the same purple line as in the first post in this thread. I noticed it was missing the color red. Once I reseated the cables in the top the problem was gone. Its a panasonic 55 inch plasma 3d tv. I was going crazy and was all prepared to shell out 1500 for a new one today. Thanks to all the brilliant help in this forum, you saved me a huge amount of money!

Just to give you a heads up the problem reappeared about a month (Almost a year since repair) ago just carried out the above again and all is well. I may not have reseated the cable ribbon correctly but it's fine now just in case you think the next time is the end and you reach for the chequebook...Do not I have the same telly as you. I always keep this page in my bookmarks on my puter and it saved the day yet again.

Last edited by Ewan Kerr; 06-22-2014 at 05:25 AM.
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