Panasonic TX-P42ST30 with exploding diodes....

[matyka]

Re: Panasonic TX-P42ST30 with exploding diodes....

Hi,anyone could help me to fix my tnpa5330 board .I have removed all the shorted Fets .
I have shorted diode near the Buffer IC. See photo
Is this would be normal ? I have measured out the board and are all Ok .

[Moreno83]

Re: Panasonic TX-P42ST30 with exploding diodes....

I found a solution for the exploding diodes on a TNPA5330 AB board.

Common failure is that after replacing the 6 FETS ( Q401/402/403/421/422/423 ) the diodes D433/432/430 will explode. The 2 small resistors ( 40K Ohm ) will give a high value or will read short.

The reason is fake parts! I replaced all fets with FGD4536 and replaced the diodes + resistors from a scrap board but it still blew up.
I found out that both DG302 were also short. One is located on Q441 ( Under heatsink and will read short on both legs ) and the other is Q451 which will read short on 1 leg. Well atlas in my case.

I replaced all parts including IC502 + Q531 with original parts and the board is back alive. Watch out that there are fake DG302 / RF1501 / 30F131 and RJP30H2A on ebay!! If the logo is almost gone using nail polish remover then you might have fake part.....

Hope it helps someone.

[ReeceyBurger123]

Re: Panasonic TX-P42ST30 with exploding diodes....

Our old friend flocko knows a good method of easily removing the buffer silicon on panasonics

[satinser]

Re: Panasonic TX-P42ST30 with exploding diodes....

I take it you've tested for short across C842. If present at least one of the buffer chips will be shorted. This I believe also can cause the demise of the trio of SMD diodes D430, D432 and D433. In my case thats exactly what I found buffer chip IC4806 blown and that Grey stuff that Panasonic put around the buffer chips is awful to remove!

[Moreno83]

Re: Panasonic TX-P42ST30 with exploding diodes....

As Tvtimmy said , both side beep is not good. A good board will beep shortly on 1 side and no beep on the other side. ( black/red propes ).

[tvtimmy]

Re: Panasonic TX-P42ST30 with exploding diodes....

It will beep for about 2 seconds. Then if you reverse the meter leads it will beep for 2 seconds. If it stops beeping both ways, thats a good start. Dont forget to reflow all the screw hole grounds!

[Moreno83]

Re: Panasonic TX-P42ST30 with exploding diodes....

No , black and red prope both on white prong connector. One way it will beep for 1 or 2 seconds. Other way around it won't beep.

A shorted board will beep constant.

[sienoki]

Re: Panasonic TX-P42ST30 with exploding diodes....

ls that neg to chassis ground n pos to white connector

[Moreno83]

Re: Panasonic TX-P42ST30 with exploding diodes....

Hi Santinser and Sienoki ,

I never found out what caused this issue but I'm still suspecting bad IGBT's. ( Fakes ).
I received a lot of TNPA5330 boards with the same issue , blown diodes on the top side of the board.

It's not only the diodes that are bad. All igbt's , diodes , resistors etc all need replacing , all resistors in that area are dead!! Also the D302 under the heatsink is shorted.

You can't test a repaired board without applying power to the board. Just hope it won't blow up. You could measure for shorts on the white prong connector , beep is bad.

I ordered the diodes that Flocko said. Im planning to replace all parts in that area because just replacing the diodes and resistors won't work.

[sienoki]

Re: Panasonic TX-P42ST30 with exploding diodes....

How do you test TNPA5330 board after repair kit fitted to see if still shorted or not..thx

[flocko]

Re: Panasonic TX-P42ST30 with exploding diodes....

This is common for these to blow the SMD diodes D430/D432+D433 when the IGBTs fail the original RF071L4S(marked 83), they can be a little hard to find now, I have always used the fairchild ES1G as a replacement as most of us would have these for Samsung/ LG Sus board repair anyway, but any 1A 400v super fast SMD rectifiers will sub for them

[satinser]

Re: Panasonic TX-P42ST30 with exploding diodes....

2 months on and I have exactly the same problem as you had with the same exploding diodes. Did you ever determine the cause?
In my case D430 and D432 both exploded their tops D433 seems to have survived though.

[Moreno83]

Re: Panasonic TX-P42ST30 with exploding diodes....

thanks for the tip! I got another repair at the moment , this time a 42GT30 but has the same boards. Repaired both boards and turned it on without the sc board connected. Starts with 207V and jumps to 216V before shutting down to 7 blinks. This is how a good powersupply should work.

Connected sc board and this repair works fine to! So advice is to check the Vsus line after repairing the powersupply board.

Im not going to repair this sc board , its too heavily damaged. Vsus line is almost cracked open and not reliable for sale.

[Alastair E]

Re: Panasonic TX-P42ST30 with exploding diodes....

Could try a bulb of 150W 240V in series with VSUS supply--It may prevent further carnage and flying silicon...
--Set will run with this if all is well, but with cruddy picture, but does help determine if its gonna work--Or not!

[Moreno83]

Re: Panasonic TX-P42ST30 with exploding diodes....

Hmm , i took a good powersupply and turned the tv and it goes to 215v before it shuts down to 7 blinks. ( with sc disconnected ).

Other ps goes to 215v. Will take another look at the sc board.

[tw2005]

Re: Panasonic TX-P42ST30 with exploding diodes....

So i had another repair , same tv with the same board. Tried it again and after the ysus repair i found out that the power supply ( TNPA5426 ) is bad also!

Common on this TNPA5426 is that the fuse + 2 other parts blow. They were fine on this power supply AND the power supply from this original thread.
I measured Vsus voltage without the Ysus board and measured 230V just on startup. This means that 230V goes to the Ysus board which probably blow the diodes on top.

Normal Vsus voltage on a ST30/GT30/VT30 is 215V.

Need to find out what is causing this. 2 power supplies now!

I would say dead short on P2 from bad SN. I vaporised the P2 track on a 50" with repetitive SC board blow ups when I was stuffing around with the bad 30F131. I'd be surprised if 230V blew anything. All the IGBTs and diodes are rated above that.

[flocko]

Re: Panasonic TX-P42ST30 with exploding diodes....

Not sure I understand what you saying. the R6015s (600v 15a) +fuse failing on the power board are a common fault after a big SN board blow up on this model in all sizes.and with no load (SN unplugged)it is to be expected that the VS would go above the correct voltage

[Moreno83]

Re: Panasonic TX-P42ST30 with exploding diodes....

So i had another repair , same tv with the same board. Tried it again and after the ysus repair i found out that the power supply ( TNPA5426 ) is bad also!

Common on this TNPA5426 is that the fuse + 2 other parts blow. They were fine on this power supply AND the power supply from this original thread.
I measured Vsus voltage without the Ysus board and measured 230V just on startup. This means that 230V goes to the Ysus board which probably blow the diodes on top.

Normal Vsus voltage on a ST30/GT30/VT30 is 215V.

Need to find out what is causing this. 2 power supplies now!

[Moreno83]

Re: Panasonic TX-P42ST30 with exploding diodes....

Hi TW2005 ,

Thanks for joining in.

The RJP30H2A thats standing up straight was like that when i first opened the TV. What you see is a IGBT that is cut in half because of the explosion haha. The customer said that some loud pops came out of the TV.

I'll replace every part in that energy recovery circuit , see what happens!

[tw2005]

Re: Panasonic TX-P42ST30 with exploding diodes....

Have you got a copy of the SC/SN fault finding for 2010 -2011 boards? The one that gives the diode check reading of the driver IC pins on the various models?

What's the deal in picture 3 with the RJP30H2 blown apart? I see that and it's not sitting straight possibly not soldered. Is that you removing it and putting it back for a photo? The other 2 look original.

Don't have any ideas except the basics being, remove all the obvious bad shorted parts, check everything else for short, check all driver resistors and if a driver IC has failed check the resistors associated with that and the 5 pin NPN/PNP.

compare the optocoupler readings to the good board.

Stick to the batch of parts that are known good just in case.