Panasonic TCP50GT20

[rcpilot82]

Hello, New poster here. I have been lurking for the past 2 days trying to solve my issue but I think a new thread is the best way.

First my TV:

TV was made sept. of 2010
Panasonic TC-P50G20
MC02650255

The issue.. Wife had set on and working, turned it off to goto work. I come home, hit the power button and nothing...just the 4 blinking lights of death. Istarted searching and came up with a P Board error. ok, took off the cover looking for blown fuses, caps or components to verify this to no avail.

I did some more looking and went to diagnosing a bad SC board. No visable blown componets after a quick look. I removed the power cables, left the ribbons on and powered it up. after about 3-5 seconds, the IC in the top right smoked itself. The chip number was M81737FP / 27Z0A 16 pin.

There in no visable damage to the buffers (didn't pull the heat sinks to see what's under them) no burn,heat marks,blown parts.

There were no previous issues with the set till now.

Questions:
1. could the original issue have been the SC board even though I am getting a 4 blinking light error indicating P Board?

2. What would cause the IC to blow on the SC board

3. where should I start to repair this?


Thanks!
Rob

PS I have a multimeter and enough electronics knowledge to get me in trouble, lol.

[tom66]

Re: Panasonic TCP50GT20

4 blinks is usually SC on this model. That IC will smoke if one of the transistors that it drives is damaged, i.e. shorted.

[rcpilot82]

Re: Panasonic TCP50GT20

4 blinks is usually SC on this model. That IC will smoke if one of the transistors that it drives is damaged, i.e. shorted.

Do you think the buffers are ok?

Tom66, Your posts and knowledge are why I joined this forum. Thank you.

[tom66]

Re: Panasonic TCP50GT20

Test the buffers as in this video:
https://www.youtube.com/watch?v=51SZsfH60EY

Panasonic buffers are very well made. It's almost impossible for a bad SC to kill the SU/SD. The only thing that can kill SU/SD is a panel failure.

[rcpilot82]

Re: Panasonic TCP50GT20

Test the buffers as in this video:
https://www.youtube.com/watch?v=51SZsfH60EY

Panasonic buffers are very well made. It's almost impossible for a bad SC to kill the SU/SD. The only thing that can kill SU/SD is a panel failure.

I just watched the video and have a question. can I pick any of the terminals coming from the Y Sustaining board to reference from or is there specific pins I should be looking for or not using to check fo continuity? I'll check my buffers tonight

Also. I know the Y Sus. boards have several versions depending on size of the Tv. My board number is TNPA5081AF . I can not find any "AF" boards in stock at the moment, Has anyone used a different suffix board with success?

Here is the best price I found so far, but they are out of stock ATM: http://www.shopjimmy.com/panasonic-t...u-sc-board.htm

[tom66]

Re: Panasonic TCP50GT20

Where the buffers screw in is your reference.

Best bet may be to find a cracked screen and harvest the parts. You may be able to use 58", 60" or 65" board in a 50" set. Maybe.

Or if you replace that IC and the nearby FETs/IGBTs, I think it should work too.

[rcpilot82]

Re: Panasonic TCP50GT20

Where the buffers screw in is your reference.

Best bet may be to find a cracked screen and harvest the parts. You may be able to use 58", 60" or 65" board in a 50" set. Maybe.

Or if you replace that IC and the nearby FETs/IGBTs, I think it should work too.

I am searching for harvested parts now. I was going to do a component level fix but the IC seems to be un-obtanium.

Thanks again for the guidance.

[tw2005]

Re: Panasonic TCP50GT20

Be careful. Bad buffers will destroy the SC. I have 1 very dead board here which was very new from a damaged in transit TV.

It was killed by both SU/SD faulty. I did not check them thinking it was rare for a bad Panasonic buffer board. It popped and now has the same failed components as the original.
The TV is running fine now after all 3 replaced . I'm talking TNPA5081,TNPA5090,TNPA5091.



Don't trust the seller to test them properly either. I've received 1 good set out 4 now and very nearly had another on it's way except FLATTVPARTS were very kind to recheck it at my request after i gave them specific components to test. They found it also faulty and removed it from sale.

In my opinion these TVs have a flaw and it's the SC/SU/SD which are failing shorting the Vsus on the PSU hence the SOS4.

Your unlucky, Shopjimmy had a complete TV board set for this for $170 One only this week but gone now. Every other TNPA5081 board gone and very few out there. He's been out for quit a while now.

Yes, you can use other versions with success. This is based purely on what i have tried.

The AF version which we have in our models, I have tested and used AP, AW. Both curently in the TVs and functioning perfectly.

You just have to watch out, the TNPA5081 is used in 42,46,50 and up models.

The 42 & 46 " versions are visibly different with 2 large blue caps where the 50 and up have 3 dark green ones. i have not compared the other components.

i am collating data on the AF,AP & AW boards I have and so far the AW has a RJP6026 at Q660(Q16660) the others AF,AP have a R50007ANX. The unusual thing here is they both have the same part number allocated in the manuals??
One's 600v the other 500V rating

Another UK seller had every one of his purchased by one person a few weeks ago.

There's a pattern out there. I have read of a couple of people taking Pansonic on for out of warranty with some success to have it fixed for free.

[rcpilot82]

Re: Panasonic TCP50GT20

tw2005

I am going to test the buffers tonight per the above instructions. So if they check out good I'll be happy. Fingers crossed...

I found where I can purchase a refurb. SC board from Best Buy (where I purchased the set from originally) for about $35 more than shopjimmy. If that is the only bad component I would probably be better off purchasing a new/refurb. board over a salvage board.

https://bestbuy.partsearch.com/Part/...furbished.aspx

I am also thinking about adding a few fans to the enclosure. a small power supply and relay would work fine and there is plenty of room for it. Any thoughts on that? worth doing?

I doubt calling panasonic would do much as my warranty expired 13 months ago.

[tom66]

Re: Panasonic TCP50GT20

Another reason why so many of these boards are faulty is a cracked screen will often kill SU/SD. Which may lead to damage to SC.

[tw2005]

Re: Panasonic TCP50GT20

tw2005

I am going to test the buffers tonight per the above instructions. So if they check out good I'll be happy. Fingers crossed...

I found where I can purchase a refurb. SC board from Best Buy (where I purchased the set from originally) for about $35 more than shopjimmy. If that is the only bad component I would probably be better off purchasing a new/refurb. board over a salvage board.

https://bestbuy.partsearch.com/Part/...furbished.aspx

I am also thinking about adding a few fans to the enclosure. a small power supply and relay would work fine and there is plenty of room for it. Any thoughts on that? worth doing?

I doubt calling panasonic would do much as my warranty expired 13 months ago.

Cooling can't hurt but I can't offer any advice there but Tom usually has some pretty clever ideas.

Yeah maybe no luck with wty but if it's a known issue really they should step up. The older sets of there's I've had seem more reliable.

Both of mine were 2 & 3000hrs. It'd be interesting to see what yours has when you get it going. You'll need the service manual for the steps to access it.

[rcpilot82]

Re: Panasonic TCP50GT20

Cooling can't hurt but I can't offer any advice there but Tom usually has some pretty clever ideas.

Yeah maybe no luck with wty but if it's a known issue really they should step up. The older sets of there's I've had seem more reliable.

Both of mine were 2 & 3000hrs. It'd be interesting to see what yours has when you get it going. You'll need the service manual for the steps to access it.

Yeah, If I can get it fixed I would be curious as well. I bet I am in the 3000 hr range easy.

I figure I can make the mounts for the fans and PS on my laser out of acrylic, mount it all on the metal back plate and be done with it. Gotta get it working first though...

[rcpilot82]

Re: Panasonic TCP50GT20

I just finished testing the buffers per the instructions above and the meter didnt make a peep so it looks like they are fine. Ill order the y sustain board tomorrow and see if that fixes it.

Fingers still crossed.

[tw2005]

Re: Panasonic TCP50GT20

Here's some measurements from my 3 SD/SU buffer sets. I checked the input side connectors SD42,SU42.
The 3 sets are, My Tv original removed which I think are still good(But never tested installed since new SCboard).
My brothers TV, and a board set purchased but supplied DOA Out of those I think 1 SD board is ok.

I've put it in a spread sheet and would love any comments or even what you have just for comparison. One of these has a dead short on the 5V line and the regulator on the associated SC board also was Short.

[rcpilot82]

Re: Panasonic TCP50GT20

So as I am waiting for my new board to come I was wondering if there is any way to test the new board to verify it is good before I install it? I am also thinking about trying to re-build the old board as a backup just in case. See here for info so far https://www.badcaps.net/forum/showthread.php?t=26322

I also had another question; is there any 12vdc ouputs on the power supply that I could use for the fans? or 5vdc to activate a relay so they turn on when the TV is powered up? My other thought was to come up with a thermocouple that would kick the fans on when a heatsink or component would reach a determined tempature.

I am not sure I would be confident enough to design a thermocouple system. I could build one, but designing electronic systems is not my strong point.

[tw2005]

Re: Panasonic TCP50GT20

Measure resistance across SC2 see if it's low or short. I don't know what the normal value is. No short though does not guarantee it's good though. The last board I purchased had no short across it.

Next I simply set the meter to diode and go hunting for shorted IGBTs. So basically anything mounted on the heatsinks. It's generally the transitors which short, I'm finding once they're removed the diodes come up ok.

You could assume if those 2 pass then it's probably ok but i have gotten past those 2 checks and still had a bad board.

The onboard LED if it is open cct, that'll trigger SOS6.

Maybe test the resistance from that 5V reg output to gnd from the panasonic ppt which I put in post #14.

I think Tom has mentioned somewhere that he's had a board with everything ok but the FET driver ic was bad.

I'd still appreciate it if you could compare my buffer resistance results to your boards as you'd be helping me too.

[rcpilot82]

Re: Panasonic TCP50GT20

OK, I am not sure if this is helpful to anyone but I tested all the Test Points to ground on the bad board and found that all of them were shorted to ground except for points 96,and 100.

TP95 would slowly rise to being open
TP58 started as a short and rose to 1161 and held there.
SC46 had pin 1 open and the rest shorted
SC41 had pins 106 open and 7,8,9 were shorted
SC42 had all pins open
SC50 had pin 1 shorted and pin 2 open
TPVSUS= shorted
SC2=shorted
most of the SC20 ribbon pins were shorted

All testing was done with the meter in continuity mode and one end on ground.

The new board arrives tommorow so hopefully good things will happen.

[rcpilot82]

Re: Panasonic TCP50GT20

More info for ya.
All testing was done with the meter in continuity mode and one end on ground.


At the buffers
SC-41
Pin value
1 open
2 open
3 open
4 open
5 open
6 open
7 open
8 open meter reads 1729
9 open

SD-42
Pin value
1 open meter reads 1729
2 shorted
3 open
4 open
5 open meter reads 1853
6 open meter reads 1841
7 open
8 open meter reads 1472
9 open

On The Y Sus.Board
SC-41
Pin value
1 open
2 open
3 open
4 open
5 open
6 open
7 open
8 open
9 shorted

SC-42
Pin value
1 open
2 open
3 open
4 open
5 open
6 open
7 open
8 open
9 open

[tw2005]

Re: Panasonic TCP50GT20

More info for ya.
All testing was done with the meter in continuity mode and one end on ground.


At the buffers
SC-41
Pin value
1 open
2 open
3 open
4 open
5 open
6 open
7 open
8 open meter reads 1729
9 open

SD-42
Pin value
1 open meter reads 1729
2 shorted
3 open
4 open
5 open meter reads 1853
6 open meter reads 1841
7 open
8 open meter reads 1472
9 open

On The Y Sus.Board
SC-41
Pin value
1 open
2 open
3 open
4 open
5 open
6 open
7 open
8 open
9 shorted

SC-42
Pin value
1 open
2 open
3 open
4 open
5 open
6 open
7 open
8 open
9 open

Better hold off installing that SC board, I think you've mixed the connector designators up. Do mean on the buffer boards SU41 & SD42?

I have concerns about SD42 pin 2 short which is the Vscn-F, I have 220k roughly that's in resistance mode, black probe on the earth plate and red on the test point. Pins are 1,3,5,7,9 on one side, 2,4,6,8 the other on the connector.

I'd prefer to see straight out resistance measurements, not diode mode. I found it hard to get consistant results on the higher readings as the circuit is charging up and if I reverse the probes, different again but pin 2 on the SU41 I get about 220k both ways, pin2 on SD42 also 218k both ways. I don't get any S/C on pins 1-9 on SD42?

[MyHD120]

Re: Panasonic TCP50GT20

Can somebody do a video of this like tom66 did for buffer boards?

https://www.youtube.com/watch?v=51SZ...DtCVe9&index=6