Panasonic tc-p42s30 TNPA5349 SN board

[ponomo1]

I have read through as many boards as I could to see all the different tests and steps that other have already taken so that I can hopefully be specific as possible with my troubleshooting adventure.
I started off with 14 blinks and I've pretty much realized that the possibility may not be the P board. My old P board was the n0ae6kk00001and since I couldn't find one I bought an n0ae6kk00005 P board version. I looked over the 2 boards very closely and everything I could visually see was exactly the same, all of the outputs to the cables were labeled and pinned out the exact same way on each board. So I gave it a shot.
I installed the new board and I went from a 14 blink to the 7 blink code. I started following the threads for the troubleshooting and I have all of the common problems as many others on the site. I have a short at the SC2 plug and my SS plug is testing clear. I'm using a Fluke DMM to test for continuity/resistance.

I have found 10 components on the SN board show continuity:
2 RF20 diodes (D641 and D642)
1 RFN10 diode (D421)
3 rf1501 diodes (D461,D481,D401)
4 30f131 MOSFETS (Q422,Q401,Q402,Q421)

I am shocked that all of these components could be damaged in one shot on a TV that is less than 3 years old. The internals look great very little dust build up no insects nesting and this is not a heavily used TV.

I just have 2 questions:
Is there anything else I should be testing before I embark on replacing these 10 pieces that are showing dead shorts across them??
Who has a repair kit that contains the most components for this boards rebuild?? I'd pefer to get the parts from a single source instead of scouring the web for bits and pieces. Some of the kits that I've see don't have all of these parts in the kits.

[tw2005]

Re: Panasonic tc-p42s30 TNPA5349 SN board

I have not looked at one of these, but a few others have with just doing the 30F131.

I'd remove them and recheck those diodes. I'm not buying all those are dead short. There are usually common cathode so you have 2 legs as anode (A) and the center or base is cathode(K). So A - A will show short.

[Hombre]

Re: Panasonic tc-p42s30 TNPA5349 SN board

Try to remove this four first: Q401 Q402 Q421 Q422. After you remove them those diodes won't probably show short (if you are teseting them correctly as tw2005 said).

[ponomo1]

Re: Panasonic tc-p42s30 TNPA5349 SN board

Great thanks for the tips. I agree that it just seems like a lot of damage that happens so suddenly and yet nothing on the board looks blown or discolored.

[ponomo1]

Re: Panasonic tc-p42s30 TNPA5349 SN board

Well I just wanted to keep you guys posted I removed the first 4 components and it still shows a short. I'll start the other components 1 at a time until the short is cleared. ughhh!!

[tw2005]

Re: Panasonic tc-p42s30 TNPA5349 SN board

Well I just wanted to keep you guys posted I removed the first 4 components and it still shows a short. I'll start the other components 1 at a time until the short is cleared. ughhh!!

Did you start with those transistors? Make sure you check them out of cct, saves replacing parts that are still good

[PinkySa]

Re: Panasonic tc-p42s30 TNPA5349 SN board

Hi to all forum members, especially to tw2005, your posts helped me a lot.

I had the issue with short pins on SN2 connector. Some MOSFETs and diodes were short.
Ordered, replaced and the TV was working for a couple of minutes. Then puff and SN2 is shorted again. Probably bad soldering of the new components or loose screws.
Now I have the situation that a lot of components are short, the same as by Ponomo1:
4 MOSFETs (Q401, Q402, Q421, Q422)
2 RF20 diodes (D641 and D642)
3 RF1501 diodes (D461,D481,D401)
1 RFN10 diode (D421)

I desoldered all a.m. components (some of them where ok). No short on SN2. But I still have short on the board where D461, D481, D421, D401, D641, D642 legs were.
I also have short on diodes near buffers (D4652, D4654, D4852, d4853). Removed D4652, D4654 and diodes are ok, but on board is short too.

I have checked pins across pins on IC522, IC521, Q521, Q551, IC502, Q531, Q501, IC684, IC501 (in accordance with tw2005 diagram from https://www.badcaps.net/forum/showth...-p42s30&page=4)
and they seems to be ok. No short on pins (except pin 1-8 on ICs, and upper and lower pin on Qs).
Also checked DG302 (Q451, Q441) and they seems to be ok. Checked randomly components across the board. Didn't find any issue.

What should I also check? Buffers seems to be ok from visual point of view (no burn marks). Not sure how to test them, because they are sealed.
Could it be, that my board is dead?

Thank you in advance...

[tw2005]

Re: Panasonic tc-p42s30 TNPA5349 SN board

Hi to all forum members, especially to tw2005, your posts helped me a lot.

I had the issue with short pins on SN2 connector. Some MOSFETs and diodes were short.
Ordered, replaced and the TV was working for a couple of minutes. Then puff and SN2 is shorted again. Probably bad soldering of the new components or loose screws.
Now I have the situation that a lot of components are short, the same as by Ponomo1:
4 MOSFETs (Q401, Q402, Q421, Q422)
2 RF20 diodes (D641 and D642)
3 RF1501 diodes (D461,D481,D401)
1 RFN10 diode (D421)

I desoldered all a.m. components (some of them where ok). No short on SN2. But I still have short on the board where D461, D481, D421, D401, D641, D642 legs were.
I also have short on diodes near buffers (D4652, D4654, D4852, d4853). Removed D4652, D4654 and diodes are ok, but on board is short too.

I have checked pins across pins on IC522, IC521, Q521, Q551, IC502, Q531, Q501, IC684, IC501 (in accordance with tw2005 diagram from https://www.badcaps.net/forum/showth...-p42s30&page=4)
and they seems to be ok. No short on pins (except pin 1-8 on ICs, and upper and lower pin on Qs).
Also checked DG302 (Q451, Q441) and they seems to be ok. Checked randomly components across the board. Didn't find any issue.

What should I also check? Buffers seems to be ok from visual point of view (no burn marks). Not sure how to test them, because they are sealed.
Could it be, that my board is dead?

Thank you in advance...

This is probably a Flocko job since he's done a few of these I believe. As far as those diodes near the Buffer ICs are concerned as you've discovered out of cct , ok. normal for those in cct to show short at those points.

I think a proper check of the buffer ICs for shorts though would be a place to start, forget visual checks.

I just don't know where you gnd the other probe to get the ball rolling on these checks.

[flocko]

Re: Panasonic tc-p42s30 TNPA5349 SN board

Buffer ICs are tested with meter set 200 ohm one lead TP VFG (this can be found just above and to the left of IC4805)then run other lead across all PDP ribbon sockets, good ICs will show OL or whatever the meter reads with leads apart, any low ohm reading show IC have failed, Diodes can show as shorted when Q401/2 and Q421/2 are showing shorted ,but after removing IGTBs (Qs) the diodes can be fine, also to note that the legs of the diodes are common and testing is done across leg and tab (north) with meter in diode mode. Testing IC502 andQ531 is done with meter set to 20M ohms to common ground all pins must show M ohms or OL I cannot give reading for you as they all differ, any low ohm reading should be changed as a pair. when you change Q401/2/421/422 change all four as a set even if one or two may be ok on test they will be weak and your board will fail in a short time,the same with Q441/451 replace as a pair. And just meter all Q gate resistors and replace as necessary . I have a post that I made about changing buffer ICs on these boards so if you need to just look it up

[PinkySa]

Re: Panasonic tc-p42s30 TNPA5349 SN board

Thx a lot, I'll test asap, and provide you with information...

[PinkySa]

Re: Panasonic tc-p42s30 TNPA5349 SN board

It seems that buffer ICs are ok. No low ohm reading between TPVFG and connector pins. the meter is set to 200ohm.
Tested Q531 and IC502 and have cca 300Kohm on some pins on both components, other pins show several MOhms.
I also found out that Emiter pins on board of Q421/2 have short with gnd.
Remark that Q421/2 are removed.
How to test IC/Q521 and IC522, Q551? The same 20M test? If is so, some pins show 0ohm.

[flocko]

Re: Panasonic tc-p42s30 TNPA5349 SN board

300k ( tested on 20M would show 00.300) should be fine , emitters on Q421/2 will show shorted to ground (this is as it should be) IC522+Q551 in all of the boards I have repaired (25+)not had to replace these but have just put meter over them and can confirm yes some read 0ohm (on a working board)

[PinkySa]

Re: Panasonic tc-p42s30 TNPA5349 SN board

Thx for your response...
Yes, 00.300 on 20M scale.
Any other idea what should I check?
I don't think that is ok to have short on board where a.m. components were.
I still have short on the board where D461, D481, D421, D401, D641, D642 legs were.

[flocko]

Re: Panasonic tc-p42s30 TNPA5349 SN board

This is correct as explained the legs of the diodes are common so will read as short and be marked on the board as A A with the tab (north) C or legs C C and tab A.If you hold the board up to the light you will see the solder pads are on the same PCB trace ? when I repair I just start by lifting the legs of suspect IGBTs and diodes and only remove them after testing when known to be faulty, but as said before I change in pairs (DG302)or as a set (4x 30F131). I do not use hot air on these for removal or replacement I have an old large 60w iron that has a bent flat screwdriver type bit, lots of flux and heat the tab till they move(the legs have been lifted when testing ) wick up pad, and tin back of new SMD (tab)lots of flux over pad heat with iron slid SMD in place, fit all new SMDs same way then with small iron solder legs

[PinkySa]

Re: Panasonic tc-p42s30 TNPA5349 SN board

Hmm, I was misleading all the time.
Yes, you are right, the legs of a.m. diodes are Anode and they are common. I also checked the datasheet of those diodes. I also checked diodes which I removed, and they are ok.
Now I understood your sentences:

...also to note that the legs of the diodes are common and testing is done across leg and tab (north) with meter in diode mode...

It seems that only 4 IGBTs are dead.

I'm still concerned about diodes near buffer ICs (D4652, D4654, D4852, D4853), is it ok to show short between pins on the board, after removing (two of them I removed)?

[tw2005]

Re: Panasonic tc-p42s30 TNPA5349 SN board

Hmm, I was misleading all the time.
Yes, you are right, the legs of a.m. diodes are Anode and they are common. I also checked the datasheet of those diodes. I also checked diodes which I removed, and they are ok.
Now I understood your sentences:


It seems that only 4 IGBTs are dead.

I'm still concerned about diodes near buffer ICs (D4652, D4654, D4852, D4853), is it ok to show short between pins on the board, after removing (two of them I removed)?

I've marked what i believe you are referring to and I believe is normal short in cct as they are for protection I suspect. I have a 2010 SN and they are showing short, ok out and it's a working board. i have 2.3 ohms across mine with a lead resistance of 0.3 ohms giving 2 ohms

[PinkySa]

Re: Panasonic tc-p42s30 TNPA5349 SN board

Thx tw2005. Yes, I referred to those diodes. So it seems that is ok.
I'll replace bad MOSFETs and put other components back together and try again.
Somewhere on this forum I found that good source for components is ebay->utsource, still true? I already ordered from them MOSFETs which I have intent to replace.
Do you guys prefer contact pads (or how they call in english) between screws and board.

[flocko]

Re: Panasonic tc-p42s30 TNPA5349 SN board

If you have removed SMD diodes and IGBTs completely from board I would replace them ,as they have been though a heat cycle twice ? replacing them would then mean a heat cycle three times, this is why I just lift the legs ,but that is your call, TW will tell you, that you are never so lucky if you have failed repair to get away with just four IGBTs

[PinkySa]

Re: Panasonic tc-p42s30 TNPA5349 SN board

I'll remember that next time

[PinkySa]

Re: Panasonic tc-p42s30 TNPA5349 SN board

Hi guys again,
After received the new components, I replaced all listed above (suggested by Flocko). Put back sn board into tv and I got short on SN2 again after switching tv on All panel ribbons were connected, screws tighten well.

Now I disconnected sn2 and sn20 and turned tv again, it blinks 8 times. Green led on ss board lights on for short period. No short on Vsus on SS board. On sn2 connector I got cca 210V.

What is killing my SN board?