Panasonic 50VT30 , Sparkles after SC Board repair.

[Moreno83]

Hey guys ,

50VT30 after 7 blink repair! Im getting pink sparkles on whiter area's.

Tpvsus is 114v
Tpvad is 69 vdc , fluctuates a bit...

I cant find the correct voltages for this model. What pot meter do i need to use? Can this be dust also?

[Moreno83]

Re: Panasonic 50VT30 , Sparkles after SC Board repair.

VR261 on the power supply controls the voltages.

The other one is for VAD right? How can i measure it to see if its correct or not?

[Moreno83]

Re: Panasonic 50VT30 , Sparkles after SC Board repair.

I do notice that the IGBT's get really hot , is that normal? Should i be able to touch them without burning my finger?

[Moreno83]

Re: Panasonic 50VT30 , Sparkles after SC Board repair.

Hmm , one IGBT ( Q421 ) just exploded. Did not touch the potmeters , they are still on its original value. IGBT is literally in half.

Back to the drawing board! :/

[ReeceyBurger123]

Re: Panasonic 50VT30 , Sparkles after SC Board repair.

Think these use chained Erc which means bad SC can kill the SS and vise versa. Check SS for S/C.

[Alastair E]

Re: Panasonic 50VT30 , Sparkles after SC Board repair.

Also--a slightly dodgy plug/socket on the heavy cables from PSU to SC and SC to SS cause the SC to self destruct in exactly the above manner.

I now remove the plugs and solder in the cables to the board making a permanent connection to PSU and SS boards.

Worth remembering Never to disconnect the SS to PSU while the SS to SC is still connected then applying power. Doing so, will also destroy the SC....

[ReeceyBurger123]

Re: Panasonic 50VT30 , Sparkles after SC Board repair.

Yep I learnt that the hard way when I first started fixing Tv's

[Moreno83]

Re: Panasonic 50VT30 , Sparkles after SC Board repair.

Hmmm ok! Thanks for the information.

Were some very loud bangs , not just one!

All 6 IGBT's + RF1501 + DAF30 died.

Will take the board back to work tomorrow and replace all components again! It might explain the sparkles....maybe bad IGBT?

[ReeceyBurger123]

Re: Panasonic 50VT30 , Sparkles after SC Board repair.

Sounds like SS failed too take that in as well it might be taking out SC !

[Moreno83]

Re: Panasonic 50VT30 , Sparkles after SC Board repair.

Thanks! I will take a look at that board for shorts. Ordered like 50 IGBTs so enough parts to play with...

[Alastair E]

Re: Panasonic 50VT30 , Sparkles after SC Board repair.

Check all the driver transistor pairs too for the IGBT's--They can leak/short and quickly ruin all your hard work!

Not sure of the numbering sequence on these--but Pan seem to have kept to the same device/job and number of IGBT through different models.

Worth checking (IF it has them) Q661, and the tiny Q701, Q702, IC773 IC771 and D702.
--Just worth looking/checking, Ive not seen one of these so cannot say whether they have the same parts sequence in them as earlier sets....

[Moreno83]

Re: Panasonic 50VT30 , Sparkles after SC Board repair.

I can take pictures if you want!

Is it true that those IGBT's get really hot? Especially Q423/422/421

[Moreno83]

Re: Panasonic 50VT30 , Sparkles after SC Board repair.

SC board is in Panasonic heaven and officially dead.

The big bangs ( 4 or 5 bangs ) on the sc board destroyed alot of components. Some pads came off and a few resistors were black/measuring OL. I seriously have no idea what happend. Maybe a resistor that went bad?

The dirt you see on the board was already there + exploded solder. Looks like alot of solder but that exploded


Resistors are measuring OL and Small diodes are also short + big diode near exploded resistor is short.
Small IC near Q621 is damaged but the 7.5ohm resistors are still ok! Only IGBTS that are short are the standard IGBTs , rest is ok.....

It probably can be fixed but i ordered a repaired board from Ebay so i can sell the tv.

Can someone tell me what caused the sparkles? SC board?

[tom66]

Re: Panasonic 50VT30 , Sparkles after SC Board repair.

TPVSUS should be MUCH higher than 114V...I doubt you'd have an image that "good" with Vsus that low (it'd basically be a few pink pixels splattered across the panel and nowt much else!)

Also Vda should surely be lower than 69V (more likely around 55-60V)

I think your meter has a problem...or the power supply has a really serious problem

During first power on of SC board use a lightbulb in series with connector for power limit test.

[Moreno83]

Re: Panasonic 50VT30 , Sparkles after SC Board repair.

I was thinking the same Tom. I'll install the SC board when i get it and test voltages first before i start up the tv. I'll double check my Fluke meters but i doubt they are bad.... VDA was measured the same as TPVSUS. I tried to lower the VDA but it did not change and there are only 2 potmeters to "play" with.

How can i test the voltages without blowing up another SC? Just use PS + mainboard only and measure voltages before it starts to blink?

First time for me that a SC board exploded haha.

[tom66]

Re: Panasonic 50VT30 , Sparkles after SC Board repair.

You can attach 150W light bulb to Vsus and see if it remains regulated under load of the bulb.
You will have to do this before it jumps to 6/7 blink code, although sometimes it will not if the boards are simply not connected.

[Moreno83]

Re: Panasonic 50VT30 , Sparkles after SC Board repair.

Thanks Tom , I will do that when i get the board. Shipped today from Belfast...should take 3/4 days i guess.

[Moreno83]

Re: Panasonic 50VT30 , Sparkles after SC Board repair.

Replacement board is working perfectly. TPVsus is 213V and little to no sparkles.

Tried it at the maximum of 217V but no differences! 213V looks good so i'll keap it this way.

[ReeceyBurger123]

Re: Panasonic 50VT30 , Sparkles after SC Board repair.

Cool beans