Panasonic tx-p42s31b

[newtothis]

Recently got hold of the above set, Upon plugging in I hear a series of relay clicks and standby LED blinks 5 - 6 times (Too quick to tell)

PSU Checks out fine and is giving all correct voltages.

I will upload pics shortly of the boards and chassis.

I am not too familiar with Plasma sets but have done one with a buffer replace and sustain VR bank replacments. Due to this I am not familiar with the layout of the set as it looks very different to the older plasma I repaired last year.

So little help with what is what and any idea will be great.

Taking pictures now

[newtothis]

Re: Panasonic tx-p42s31b

Pics

[tw2005]

Re: Panasonic tx-p42s31b

to get an idea of where to start , an accurate count of the sos blinks would be helpful. they do pause and repeat so you should be able to figure it out. I'm expecting 6 or 7 indicating SN board as that is a more common one. Also, with the mounting screws on that SN board especially where the earth points are, are they all the same type or look like they've been replaced?

look for shorted transistors on the SN board especially the surface mounted.

[newtothis]

Re: Panasonic tx-p42s31b

Ok so disconnected SS and still get the green LED blink with same pattern, Disconnecting SN results in the green LED flashing around 20 times then 7 RED blinks

[newtothis]

Re: Panasonic tx-p42s31b

Hmm actually disonnecting the SN causes 7 RED blinks, So I am i right in assuming it is OK?

Pointing towards A board do you think?

[newtothis]

Re: Panasonic tx-p42s31b

Oh screws have certainly been replaced

[newtothis]

Re: Panasonic tx-p42s31b

Oh wow! Let me get a pic of this!

[tom66]

Re: Panasonic tx-p42s31b

Probably shorted SN. Do you have Vsus? It will cause flashing green then dead or lit LED.

[newtothis]

Re: Panasonic tx-p42s31b

I don't know how the hell I didn't spot this straight off! The history of the TV was that it went to a TV repair shop with a 7 RED blink and came back with a 5 green blink and a quote of £90 to repair it.

That damage is certainly done by somebody and not a failure! I will test the transistors and if they are fine I will retrack the board and see what it does.

[newtothis]

Re: Panasonic tx-p42s31b

Forgot to add pic

[tw2005]

Re: Panasonic tx-p42s31b

Forgot to add pic

Yeah that's funny. Obviously they've tried to remove the short on the SN board and who knows what but would have to wonder if a professional shop would do that. I would ignore the 5 blinks and focus on getting a new board or a kit to repair it.

I did a board for a 50S30 and only 4 x 30f131 were required but it's not always that simple. search the board number and see what's in the kits for an idea.

[tom66]

Re: Panasonic tx-p42s31b

I recall 5 blinks occuring on these if the 15V is short/low which could happen if gate driver IC is shorted...

[newtothis]

Re: Panasonic tx-p42s31b

I lose the 7 blinks when removing the SN board. Obviously cannot tell if the 5 blinks is a false read or not as the board is buggered.

Yeah definitely going with a kit for repair as these boards are going for around £150

[Alastair E]

Re: Panasonic tx-p42s31b

Be aware, The Kits dont always contain everything to repair these boards....

NOT repairing properly and getting all the faults first time around, and ALL the new parts as well as probably more will be destroyed. You'll need to replace ALL the tiny driver devices on ALL the dead IGBTS, as well as some of the undamaged IGBT's particularly around the ERC circuit.

Even though a good replacement is £150 and repairs to the board are £80, you may find this a better option, as then at least you'll know you have a good base to work on.
These are NOT easy fixer-uppers, They are a CRAP design as they run WAY too hot and have a very limited lifespan. The picture when working on the ones Ive done is pretty disappointing too!

[newtothis]

Re: Panasonic tx-p42s31b

Most of the IGBT's are reading as closed with only 2 reading as open.

Set isn't worth the repair

[tom66]

Re: Panasonic tx-p42s31b

Seriously? It cost me about £20 to fix a U30B, which is practically the same minus Smart features.

PM me, I'll pick up the set off you if you're gonna trash it.

[Alastair E]

Re: Panasonic tx-p42s31b

IF most are short, then maybe someone's been in there--thought it a quicky and replaced a few they found short--Then killed 'em all because they didnt do it right!

Ive had one of those, Took a fair bit of messing round to cure it. I think in the end I replaced all the TO220 SM devices and nearly all the driver devices and a 5V reg too...

Either get a new board, Have yours repaired or part it out, if you are not confident doing it as it'll end up costing you more in time and effort let alone money.....

[newtothis]

Re: Panasonic tx-p42s31b

Yeah I will part it out

Getting a new board definitely is not worth it, Can get a working set for £200

[Alastair E]

Re: Panasonic tx-p42s31b

Flog it to Tom, He's a masochist, enjoys the challenge!

[newtothis]

Re: Panasonic tx-p42s31b

Decided to repair the SN board on this.... Replaced all IGBT, drivers etc... No shorts left on board at connector, All buffer IC's show no short.

So install the board and plug it in... Relay clicks... SN green LED lights up Sweet...... CLICK!.... Set shuts down LED goes off on SN... Check SN... Shorted.

I changed EVERY IGBT, Diode etc etc so no fault on my part. Fracture of the panel cause SN to short like this?