Panisonic 42inch TCP42S30 not working!!

[Glitcher]

Re: Panisonic 42inch TCP42S30 not working!!

If this is the case, there appears to be a lot more mosFets than usual that are fried. [D642,D641,D461,D481,

Those are actually diodes. They have the same look and package as a FET but its different. I'm assuming you measured them shorted from pins 1 and 3? In that case its normal.

**Think of it as two separate diodes in the package, where pins 1 & 2 is a diode and pins 2 & 3 is another diode. And if I remember right the direction of flow would point toward pin 2.

[Hok]

Re: Panisonic 42inch TCP42S30 not working!!

Great, thanks for taking the time to help out a n00b.

R401,402,421,422 all read 7.5-8 Ohms. Have removed the corresponding igbt's thinking they were faulty - only 1 is faulty.

q451 and q441 are faulty, but the corresponding resistors both measure about 6 Ohms

Q621 and Q622 appear to be faulty - their corresponding resistors measure 115 Ohms (there are additional resistors as well, R682 and R681 that measure 10 Ohms each)

Q601 appears to be shorted, and R601 reads 1 Ohm (There is discoloration in the holes around Q601 and Q

Q661 and Q660 appear to be shorted.

have lifted both legs on all of the shorted transistors - only one left is:

Q600, which appears to be shorted. Board still showing short, cross your fingers for me on this last piece...

[Hok]

Re: Panisonic 42inch TCP42S30 not working!!

It's clear that I'm out of my league

lifted one leg on Q600, and board is still showing short. I have no way of testing IC502, but I doubt that it could be causing a short. I have tested all the normal components that come in the repair kits, as well as a multitude of others. Was hoping that I could find the issue on my own, but I think i'm grasping at straws at this point. These boards are hard to come by and expensive, as well...

[Hok]

Re: Panisonic 42inch TCP42S30 not working!!

I guess the current Panasonic Plasma in this size cost about 3.5x the cost of these boards.. Ugh i'm really hating televisions right now.

[tw2005]

Re: Panisonic 42inch TCP42S30 not working!!

So at SN2 in diode mode, what happens when you probe across the pins

[Hok]

Re: Panisonic 42inch TCP42S30 not working!!

Can I go through the TP points on the back of the board to isolate where the fault(s) is/are? If so, how would I go about it?

[Hok]

Re: Panisonic 42inch TCP42S30 not working!!

sorry just posted that and it refreshed, TW - saw your post...
what happens is 0L one way and .453 volts the other, on audible i get 0L both ways

[tw2005]

Re: Panisonic 42inch TCP42S30 not working!!

sorry just posted that and it refreshed, TW - saw your post...
what happens is 0L one way and .453 volts the other, on audible i get 0L both ways

That's not short.

[Hok]

Re: Panisonic 42inch TCP42S30 not working!!

oops. Well that was a headache I probably didn't have to live through, had i had a bit more knowledge.

Does it indicate that I have isolated the faults?

[tw2005]

Re: Panisonic 42inch TCP42S30 not working!!

Indicates no longer shorted which is what would have triggered the original condition. Impossible to say you've isolated the faults as there are several blown components.

What is making this difficult is knowing if you are testing the parts correctly and interpretting the meter right.

what type of meter have you got? I'm not understanding OL/reading in diode and OL/OL in audible.

[tw2005]

Re: Panisonic 42inch TCP42S30 not working!!

http://www.moduslinkptstvboards.com/TXNSN1PKUU/

Intersting the AD revision will also work and subtitute but they charge $30 less?

http://www.moduslinkptstvboards.com/tnpa5349ad/

[Hok]

Re: Panisonic 42inch TCP42S30 not working!!

thanks for those links, I first exhausted that search before I began to work on this. Understand your doubts about my abilities.... and I respect your patience, knowing what a pain it can be for you to think in Latin when i work in dogspeak
Using a Mastech DMM - the diode mode has a ->+ setting that shows volts or 0L and the audible setting 0))) which gives the beep and shows ohms on the display

[Hok]

Re: Panisonic 42inch TCP42S30 not working!!

I was testing across SN2 with the audible setting, and not the diode mode, this is why I assumed I had not yet found the fault(s) with the board - i was getting 0L every time, in both directions.

[tw2005]

Re: Panisonic 42inch TCP42S30 not working!!

thanks for those links, I first exhausted that search before I began to work on this. Understand your doubts about my abilities.... and I respect your patience, knowing what a pain it can be for you to think in Latin when i work in dogspeak
Using a Mastech DMM - the diode mode has a ->+ setting that shows volts or 0L and the audible setting 0))) which gives the beep and shows ohms on the display

OK, that probably explains the results. So in diode mode if you short the probes it shows 0 but there's no audible feature or noise in that mode?

[Hok]

Re: Panisonic 42inch TCP42S30 not working!!

diode mode shows 0L in one direction and .453 volts in the opposite direction, and there is no audible in that mode.

to use the audible testing, I go to the 0))) setting, which offers a beep or constant beeping and measures in ohms

[Glitcher]

Re: Panisonic 42inch TCP42S30 not working!!

sorry just posted that and it refreshed, TW - saw your post...
what happens is 0L one way and .453 volts the other, on audible i get 0L both ways

That seems about right, that's the exact reading I had on mine. If it was still shorted it would just read low resistance no matter what setting you used.

Now you just need to get those parts replaced and youre good to go!

[Hok]

Re: Panisonic 42inch TCP42S30 not working!!

i see... well i hope it's that easy, as it stands i've got 2x DG302's and 6x 30F131's disconnected from the board. Guess I oughtta make sure i need them before I order them...

I do get a voltage reading from 2 of the 30F131's when they're connected, but not when they're disconnected. Same with the 2 DG302's. Funny, because I believe I was told to check resistance on those, which I thought was measured by Ohms, so I was on the wrong setting perhaps?

[tw2005]

Re: Panisonic 42inch TCP42S30 not working!!

I'd like you to go back to all the transistors and diodes again and see if we can be methodical and clear about the results.

What do you think? Or just buy the kit and take a gamble?

[Hok]

Re: Panisonic 42inch TCP42S30 not working!!

i would love to know what's wrong before I order it, so I'm game. Keep in mind, that I have four transistors off the board... (30f131's) Can test them, but broke the leg off one of them so don't think i'll be able to reuse that one.

[tw2005]

Re: Panisonic 42inch TCP42S30 not working!!

i see... well i hope it's that easy, as it stands i've got 2x DG302's and 6x 30F131's disconnected from the board. Guess I oughtta make sure i need them before I order them...

I do get a voltage reading from 2 of the 30F131's when they're connected, but not when they're disconnected. Same with the 2 DG302's. Funny, because I believe I was told to check resistance on those, which I thought was measured by Ohms, so I was on the wrong setting perhaps?

Ok, the 2 that give no reading out of cct (OL i assume) should be ok. These fail dead short across all 3 pins usually.

Measuring resistance is fine if you know what you're looking for which is a dead short or 0 ohms.

So it sounds like the DG302 are also fine. I'll find a video which shows how to test them out of cct in diode which involves switching the transistor on otherwise you see no reading in diode.