Panasonic 65vt20

[poldog]

Hi,

I bought a plasma with a defect.
After some minutes, with light and contrast at normal level, flickering horizontal bands appears on the screen.
you can see the defect on this video:

https://www.youtube.com/watch?v=TysL...m-upload_owner

I found that when I spray the ysus board transistors with "ice spray" the defect disappear.
so I changed this board but the changes are minimal, the defect appear the same after more minutes. I think that this new board is less cooked than the old one.
On the power board I've found two caps with belly and I've changed...nothing change.
the VSUS measured is 206V.
...I don't have more ideas...please help me

[Moreno83]

Re: Panasonic 65vt20

This looks like a bad connection on the tabs. ( Orange tabs going from panel to SC board/SS board ). Are all screws connected properly on the boards?

[poldog]

Re: Panasonic 65vt20

Hi Moreno, why you suggest this? I think that a problem on this connection generates single bands. the problem concernes the entire panel and when the ysus board is hot.
I will check but I don't understand why the ysus board heats so mutch

[tw2005]

Re: Panasonic 65vt20

Hi Moreno, why you suggest this? I think that a problem on this connection generates single bands. the problem concernes the entire panel and when the ysus board is hot.
I will check but I don't understand why the ysus board heats so mutch

Sections of the Sc board do run hot. Could it be just a coincidence when the Sc is hot this occurs as other boards are running too and maybe some heat soak.

2 SC boards,same issue? If these have an A board and separate D board maybe try freezing those because it looks very blocky and scrolling

[poldog]

Re: Panasonic 65vt20

thanks tw2005. When I have open the tv the first boards that I've tried to freeze was been the A and the D board.
I spent all the day with the multimeter searching for some defect on the SC boards bun nothing strange...
There is a difference between the two boards. in the new board the defect appears after 40 minutes in the old one after 5 minutes.
tonight I've done a try. I'v putted a CPU fan on the heat skins of the SC boards (the old one) and the temperatures was a lot less high. the defect doesn't appears.
Now I'm thinking to do an hack. I want to connect all the heat skins with an aluminium foil, and blow the board with one or two small fans.
Do you think that there is a possibility that neither the SD or SU boards are fault?
I have a lot of fear about the possibility that the panel isa damaged...can you keep calm me about this?
Thanks a lot,
Ivan

[tw2005]

Re: Panasonic 65vt20

well certainly you have a very unusual fault then. I would not have thought SC with 2 board the same but slightly different times. I was thinking A, D or SD as a longshot. I would not have thought panel issue or damage.

Cluelesss on this one then I'm afraid but the scrolling coloured bars I just thought may have been an issue with the video data process which I'm not knowledgeable enough with.

I have read one post with display defects which went with cooling and they replaced the Sc to sort it. I know how to fix them when they short but not this sort of issue.

having tried 2 sc and you get same result but not in the same time does not help the fault finding much, just throws more doubt because you see a change but not a fix. Are both faulty? that I do not know.

[poldog]

Re: Panasonic 65vt20

Hi, maybe is incredible...but with my other Plasma I needed to replace the main board.
I bought an used board and I've mounted it. the board became to do something wrong after one hour....I thought that was impossible that two boards was fault.
I've changed other several boards........at the end the problem was the second main board that was fault too.
Do you think that if I fix the issue with the "active cooling" hack will be fine?
there is some measurement that I can do for understand something?
Really thank you very much,
Ivan

[Ltank]

Re: Panasonic 65vt20

On the Timing Control Board should be a jumper to generate test patterns. Disconnect the cable from the main board to the control
Board. Leave all the others intact. If the screen displays all the test patterns OK, then your M.B. is at fault.

[poldog]

Re: Panasonic 65vt20

Thanks a lot Ltank! tomorrow I will try. This evening I found a way...not so elegant but a way...
I've connected 3 CPU fans in parallel with the original fan of the tv and the SC board now is cold...the defect disappear
Ok is a crazy solution but works!
I will keep in touch with the evolutions.
the helps of this forum are very important.
Thank a lot
Ivan

[tw2005]

Re: Panasonic 65vt20

On the Timing Control Board should be a jumper to generate test patterns. Disconnect the cable from the main board to the control
Board. Leave all the others intact. If the screen displays all the test patterns OK, then your M.B. is at fault.

you sure about this or are you thinking Samsung? First I've heard of this, never read anything or read of anyone jumping anything on a panasonic to generate test patterns

[poldog]

Re: Panasonic 65vt20

ok, now also with the fans the defect appears. there is a led on board (D16583) that is power on.





now, i'm thinking about the possibility of a defect of the Tnpa5149 1 D BOARD.
Is it possible?
i'm so confused... help me please
Thanks,
Ivan

[tw2005]

Re: Panasonic 65vt20

ok, now also with the fans the defect appears. there is a led on board (D16583) that is power on.





now, i'm thinking about the possibility of a defect of the Tnpa5149 1 D BOARD.
Is it possible?
i'm so confused... help me please
Thanks,
Ivan

LED on is normal operating condition.

I think if it was me I'd get the TV cool again , turn on so no defect and get a hair dryer and try warming a particularr board up to see if the TV faults quicker.

[tw2005]

Re: Panasonic 65vt20

there is a method to turn these on with the A board isolated and produce a white screen with the D board. That may be something to try, not sure if that will help prove anything but may be worth a try just to see what does happen

[poldog]

Re: Panasonic 65vt20

Thanks! I will try and I will let you know

[poldog]

Re: Panasonic 65vt20

ok,
I've followed your suggestion and the defect is the same.
the "A board" is ok.



now I have two opportunities:
1)100€ for a brand new SC board
2)40€ for a used D board

[tw2005]

Re: Panasonic 65vt20

ok,
I've followed your suggestion and the defect is the same.
the "A board" is ok.



now I have two opportunities:
1)100€ for a brand new SC board
2)40€ for a used D board

Ok, so if you can't get a change to occur manipulating heat and I would focus on the D board then it will have to be a gamble but since you've tried another SC I would be going for the D board. But there is one thing I'm unsure of and can a bad buffer board do this in which case I'd guess at the SD

These D-boards are known to fail and cause digital patterns to occur which is what I see as you have multiple bands or blocks of distortion which appear to be all the same width/height.

Even if the D board does not fix this it would be a handy spare to have if you intend keeping this TV.

With the D boards make sure you get the same revision board as each sized panel will have it's own board. The panel data/config is stored on that D board in an eeprom/ spi flash chip. It wont be a case of getting any TNPA5149

I suspect it may be this version but you're in Europe but this is the US 65VT25 board

[tw2005]

Re: Panasonic 65vt20

there's also some other things I'm wondering about. If the blocks that occur are the same distortion or colour for each position and by that what I mean is does the same coloured band occur only in the one postion.

If it does in service menu you can flip the image. If the image remains unchange at all then that may point away from the D board but if for example a particular defect at the bottom then moves to the top the that suggests to me d board since we've already established A-board isolated , same problem.

I can't be sure of this but I think the more things we try we may stumble on some more clues.

If you look at this snip, and see what you can find. keep the images coming especially when testing for us to see.

The second image is the test patterns and it says any defect is D board or panel for 23 of the 24.

I think the D board case is getting stronger. I think that's the best guess I can give you like I said they do fail and also can cause a 1 blink fault too.

[poldog]

Re: Panasonic 65vt20

Ok,

I've bought the D board.
I will keep you in touch.

Thanks,
Ivan

[tw2005]

Re: Panasonic 65vt20

Ok,

I've bought the D board.
I will keep you in touch.

Thanks,
Ivan

good luck

[poldog]

Re: Panasonic 65vt20

Hi,

the problem was the SD board. I've changed both SD and SU cards and now the TV is ok.

Thanks a lot.
Ivan