Panasonic tc-p42s30 TNPA5349 SN board

[PinkySa]

Re: Panasonic tc-p42s30 TNPA5349 SN board

The 4 MOSFETs are dead.
Could it be that I'm using cheap parts? From where you are purchasing your parts?

[flocko]

Re: Panasonic tc-p42s30 TNPA5349 SN board

did you fit all new transistors and diodes ? or were they a mix of tested good old and new, did you test the components after you fitted them, you have missed something along the way. I think I have put on here some were that the DG302 do not always show as shorted ,but in diode mode will show as leaky and will cause problems, as will Q531 and IC502,al of my parts come from China and I have no problems but I all ways check them before fitting and do not assume that because they are new they do not need testing. the soldering of the SMD components can also be the problem as the four IGBTs that keep blowing are all connected, one bad soldered tab on one will take out the others, this is why I say testing the board after your repair is a must do. I hope this is of help to you in getting this set working again

[PinkySa]

Re: Panasonic tc-p42s30 TNPA5349 SN board

Thx Flocko for response...
Yes, I replaced them all with a new parts.
I tested them after I've fitted them, also tested the soldering physically as well as electronically. After all, tested on SN2 and was no short.
I couldn't find on this topic any explanation how to test DG302, just for near by IC502 and Q531. Pls, could you provide quick info?

[flocko]

Re: Panasonic tc-p42s30 TNPA5349 SN board

The Panasonic DG302 IGBT, full part number is DG3C302CL and is tested the same as the other IGBTs on the board ,but can fail without showing as a dead short and is easily missed (if checked in diode mode it will show higher or lower reverse bias when compared to a new unit ), and as it forms part of the sustain and recover circuit can lead other components to fail. also it should be noted that with Q441/Q451 faulty this will not show as a short on SN2

[PinkySa]

Re: Panasonic tc-p42s30 TNPA5349 SN board

Thx.
I'll check them and compare with the new DG302.

[Alastair E]

Re: Panasonic tc-p42s30 TNPA5349 SN board

Often on these sets generally, if a IGBT/MOSFET fails, it will take with it the Driver components. These are often small S.M. dual transistors or gate chips.
--Happens particularly around Q601 and its drive components, sometimes even going back to the small 5V reg chips too.

Failing to find just one faulty drive part and replacing everything else--and you'll end up with everything blown again.

The Y-SUS can be thought of as a double 'H' bridge, so anything turning on on any leg of the 'H' --when its NOT supposed to,-will kill itself--and everything else!

Not unusual for up to 20 odd parts to fail--All in an instant!

[PinkySa]

Re: Panasonic tc-p42s30 TNPA5349 SN board

Yes, you are right. After my second failure to repair, I had short on Q501 and IC501 which I changed. I'm checking all parts before turn the tv on. I'll double check them again.

[flocko]

Re: Panasonic tc-p42s30 TNPA5349 SN board

Repaired a board today that did not have the normal short to SC2 ,and no Q401/2 Q421/22 shorts just showing short C-E on Q441(DG302) and shorted D481 (RF1501) that went when I lifted the legs of Q441. I replaced Q441/Q451/ IC502 and Q531 tested all gate resistors and other transistor and diodes but all was fine. the board has been running in my test set all afternoon and will be left running till later tonight,easy one for a change

[PinkySa]

Re: Panasonic tc-p42s30 TNPA5349 SN board

I checked resistance on both DG302, between Collector and Emiter I have 10.5Kohm, between Gate and Collector I have OL.
Also checked Q501, IC501 and IC684 and there is no short.
Flocko, why you changed Q531 and IC502 on a.m. board? They were short, or just in case?

[flocko]

Re: Panasonic tc-p42s30 TNPA5349 SN board

If i have a problem with Q441 or Q451, I change them both and the drivers, same with any of the Q401/2 Q421/22, if one or two have gone I replace all four,same with any diodes, if they are paired I change both if one has gone. As all the boards i repair are sold the last thing I want is for them to fail, I need to know they will last. I also put as little heat as i can though SMD components. The only time I use hot air is for getting buffer IC off,even with them I run low melt solder with an iron first, and then run very low temp and air

[PinkySa]

Re: Panasonic tc-p42s30 TNPA5349 SN board

I've changed both DG302, IC501 and Q531 also all 4 IGBTs. As you suggested I put little heat. Now my board is not shorted after powered on but I got 6 blinks code. The green LED on SN board turns a bit on after switching on. Any idea what could be wrong now? Thx

[flocko]

Re: Panasonic tc-p42s30 TNPA5349 SN board

I thought you had this fixed ? its been a long time from your last post.did you check the gate resistors ? if you are not seeing any shorted parts try changing IC501+Q531 again, some have said they received faulty parts, also check your soldering , do you see both SN + SS green LEDs light? do they stay on for the same amount of time

[PinkySa]

Re: Panasonic tc-p42s30 TNPA5349 SN board

Unfortunately I haven't fix it yet. If I did, I would let you know... I've been waited the parts too long...
No, on both boards the green LED is on but on SS board the LED is brighter. Otherwise on SN board is almost unvisible.
Before power on I checked all soldering, especially tabs on diodes and transistors.
I've checked all new parts before putting in and they had no short.
I will change the parts which you suggested.

Thx for your help.

[tw2005]

Re: Panasonic tc-p42s30 TNPA5349 SN board

I've changed both DG302, IC501 and Q531 also all 4 IGBTs. As you suggested I put little heat. Now my board is not shorted after powered on but I got 6 blinks code. The green LED on SN board turns a bit on after switching on. Any idea what could be wrong now? Thx

So it failed, 6 blinked after power but all the parts are still OK that you replaced?

On the board there's a large inductor coil and themn nearby there's 2 SMD diodes. This is just a random guess but see if they're shorted or any others of that style are ignoring those ones near the buffer ic you thought were bad at the beginning.

I've missed a shorted diode like these once and nothing blew but 6 blinked and that was the 5081 boards I've done

[firerock]

Re: Panasonic tc-p42s30 TNPA5349 SN board

Hello guys,
Thanks to your pieces of advice, I've finally got my TNPA5349 working, yay! But one thing still bugs me a lot.
Q601 (R5007anj) is hot like a hell (90-100°C); at the same time, another R5007anj device, Q660, is just a bit warm.
I've opened the R5007anj specs and found the only thing concerning the working temperature, namely "Junction temp", which is 150°C. Not far away, I'd say.
For now, I'm going to attach a radiator to Q601, but something is wrong here, I think. Especially, if to take in account AlastairE's words

"--Happens particularly around Q601 and its drive components, sometimes even going back to the small 5V reg chips too."

So, I suppose, one or more elements linked to Q601 had gone broken, which, in turn, makes Q601 working in a wrong temperature mode. But which element(s)? How to diagnose?
Or, maybe, I'm completely wrong, and this pattern is completely OK for this design?
What do you think?

Thank you in advance for the answers!

[andyb1712]

Re: Panasonic tc-p42s30 TNPA5349 SN board

Not sure if anyone is still taking part in this thread but I've just started work on a TNPA5349 from a TX-P42S30B and so far not had much luck...

SN2 was short and Q401, 402, 421, 422 were blown, so I replaced them along with D401 and 421, which appears to be the 'general' failure mode for this board.

On power up, all 4 x IGBTs blew again, so clearly I missed something else.

Next attempt I removed Q441 and 451, which although not shorted came up as just as capacitors on my Transistor tester.

Replaced those and the other 4 but this time I fitted all new driver transistors and buffer chips too, so about 16 components in total. Checked all around Q621, 622, 601, 660 and 661 and no sign of damage in those areas either.

Powered up and bang, back to square one again!

I've checked the buffer output chips by probing between TPVFG and all the connector pins but no shorts were found there, so its not a blown buffer taking out the IGBTs.

Is there anything else on this board I need to check as I can't find anymore blown parts and I'm reluctant to rebuild it again until I can figure out why it keeps failing.

Replacement boards are available on eBay but at £75 they are about what the set is worth now, so I'd rather repair then replace.

[tvtimmy]

Re: Panasonic tc-p42s30 TNPA5349 SN board

Send a pic of your replacement igbt's. Where did you scorce them? Also, send a pic of your transistor tester.

[andyb1712]

Re: Panasonic tc-p42s30 TNPA5349 SN board

Thanks for the reply.

My first attempt used genuine Panasonic 30F131s salvaged from a working x-sus board. I went this route as I figured better than the risk of fake parts as these are hard to get now.

Second attempt used FGD4536 devices to replace all the 30F131s and both DG302s.

The 4 x in place of the 30F131s went short again.

My source for the FGDs was a Chinese eBay seller called e-best_trade. I've been using them a while now and all the parts received look genuine, with no signs of numbers being sanded and remarked etc. I've sucessfully fixed a few other y-sus boards with their parts and they've been ok.

Pics attached of 2 surviving FGDs in place and my transistor tester.

[tvtimmy]

Re: Panasonic tc-p42s30 TNPA5349 SN board

Check Q600. Also resolder the screw holes top and bottom of SN.

[andyb1712]

Re: Panasonic tc-p42s30 TNPA5349 SN board

I will check and replace the remaining power devices as necessary.

I prefer to remove solder from the bolt holes both sides rather than add any. I then fit new screws with split locking washers and flat washers.

Later Panasonic sets had no solder around the fixing points and used machine screws with split locking washers and flat washers, which don't come loose with time and heat cycling.

This set has 8 fixings and I could have removed 4 by hand they were so loose!