panasonic th-42pz77u 6 blink led

[SeanS]

I have a Panasonic TH-42PZ77U; I am experiencing the 7 blink power issue. I did the usual troubleshooting by trying a new outlet and unplugging all the cables from the plasma. Then I downloaded the tech manual and went through the troubleshooting steps. When I unplugged the SU board the TV powered up so I ordered an SU board. When I installed the new SU board the same thing is happening. Could the SC board be frying the SU board when I power it up? Your help would be very much appreciated.

Kind of the same issue here...tv attempts to power up when plugged in (clicking noises, normal I think) and then I try to power on. TV attemps to power on for about 5-10 seconds then clicks off and I get 6 blinks of the LED.
I tried all the normal trouble shooting and then cleaned out the back components of any dust or debris. Downloaded the service manual and:
1.) disconnected the SU board, plugged in tv and tried to power up. same results. reconnected SU.
2.) disconnected the SD board, plugged in tv and tried to power up. Same results. reconnected SD
in either case, the screen remained blank and I could see nothing.
3.) I did not see any LED on the SU or SD board as the manual suggested but I did see the one on the SC board and during all power ups, it never came on.
I want to fix this myself, I have a multi-meter and tools to test anything, but I have very little knowledge in electrical components and circuits.
If there is anything else I can test, if someone is willing to walk me through it and interpret the results, I would be extremely grateful. The wife and I cannot really afford a new tv right now, and I was raised to get off my arse and fix it if I can. besides, I would potentially fix something my dad says is "too new" for him...really? I thought he could fix anything...
I am assuming from other threads I have read here that it might be the sc board but it could also be the plasma screed itself? But if its the screen, I really don't want to fry another SC board or waste the money if it's indeed the screen.
Any help and guidence (walk me through it in laymans terms) would be sooo appreciated! I have attached pictures...

[tw2005]

Re: panasonic th-42pz77u 6 blink led

6 blinks is usually SC board, 7 blink can be either. There's quite a few threads you could read up on if you use the search and model of this TV.

here's just 1 i picked.

https://www.badcaps.net/forum/showth...ght=th-42pz77u

Most reports appear to be 7 blink but checking the surface mounted FETs for shorts would be a good place to start.

Trust you have a multimeter. Self replacement of those FETs can be tricky without the right gear and experience. Quite a few have torn the pads out due to being unable to get enough heat in to melt the solder. the PCB draws the heat away a lot due to the size of the copper lands.

[SeanS]

Re: panasonic th-42pz77u 6 blink led

thanks much! that was quick...So I'll assume it's the SC board and the FET cluster has a bad element. from the pic in that thread, it looks like I have 26? man...Considering I have only sodered basic wiring together and haven't even thought about attempting chips on a board, would you recommend I attempt this or take it to a shop? I'm not sure what a new board costs but I can easily see myself burning through the board, lol...or not lol...
is there a way for me to test the SC board to make sure it is the problem, and the FET's are the problem on the board with out going through that process? or do I just do it and hope I find a bad one? or just replace the whole board for the lower skilled like myself?
***Quote***
Default Re: Panasonic TH-42PZ77U SC board repair
Thanks so much for the help. That is a set of directions I can follow! I have a friend at work that has soldered lots of electronics and said he'd help.

And just to be 100% crystal clear, do I need to desoldier the two legs of the FET every time I test in the sequence with my meter (pic 2 above)? Or do I only need to desolder for replacement of the bad FET? From what I think I understand, I'm trying to find the bad electrical pathway inside a FET and then replacing..?


Lastly, if we find the bad FET how do I locate one online (the part number on the bad unit?)?

Thanks!!!

He never got a reply on the desodering of each FET in order to test...Do you have any input on this?
Thanks so much!

[tw2005]

Re: panasonic th-42pz77u 6 blink led

thanks much! that was quick...So I'll assume it's the SC board and the FET cluster has a bad element. from the pic in that thread, it looks like I have 26? man...Considering I have only sodered basic wiring together and haven't even thought about attempting chips on a board, would you recommend I attempt this or take it to a shop? I'm not sure what a new board costs but I can easily see myself burning through the board, lol...or not lol...
is there a way for me to test the SC board to make sure it is the problem, and the FET's are the problem on the board with out going through that process? or do I just do it and hope I find a bad one? or just replace the whole board for the lower skilled like myself?
***Quote***
Default Re: Panasonic TH-42PZ77U SC board repair
Thanks so much for the help. That is a set of directions I can follow! I have a friend at work that has soldered lots of electronics and said he'd help.

And just to be 100% crystal clear, do I need to desoldier the two legs of the FET every time I test in the sequence with my meter (pic 2 above)? Or do I only need to desolder for replacement of the bad FET? From what I think I understand, I'm trying to find the bad electrical pathway inside a FET and then replacing..?

Lastly, if we find the bad FET how do I locate one online (the part number on the bad unit?)?

Thanks!!!

He never got a reply on the desodering of each FET in order to test...Do you have any input on this?
Thanks so much!

First things first i think.

If you know how to check continuity or for short circuit, probe all 3 combinations of the connections of the FETs and see if shorted. there's 2 legs and the Tab.

They're in parallel so if 1 is short in a bank then the others will be shorted.

if nothing is shorted then we'd have to look elsewhere but this is where experience on this particular model would be handy.

If there are shorts there's no other way but to the lift the legs 1 transistor at a time really to isolate.

never worked on this model so I'm assuming the Sc is primary suspect.

Start with finding a short on those FETS first and see .

sending this to a shop, probably not worth it.

[SeanS]

Re: panasonic th-42pz77u 6 blink led

ok, I will try...I've never done any of this before but I have a multi meter so I will follow the steps in that post you mentioned. but like he asked, do I need to desolder the legs before I test them or can I test as is, with them connected to the board? I'll start tomorrow afternoon and post the results...Thanks! edited*** wait,...it looks like you answered the soldering question...only desolder if I find a short in the bank...got it...Thanks!

[SeanS]

Re: panasonic th-42pz77u 6 blink led

Yep...definitely not sure of what I am doing when testing FET's or how to interpert the results. would you have any time to help me through this? I can post pictures and data to help...
Thanks!

[SeanS]

Re: panasonic th-42pz77u 6 blink led

well...last ditch effort before sending this to the shop. I have never tested fet's before or have a lot of electrical circuit knowledge. I have used multi-meters before but this is completely new. I have not been able to find any info on exactly how to test these nor how to interpret any results I find. SO....I tested how I best understood TW2005's answer and the results are below. If anyone has any input or questions on how I tested, let me know. Otherwise it's going to have to go to the shop and see what the verdict is. It's been disassembled for 3 weeks while I combed through here trying to figure out how to diagnose this stuff...time's run out on Friday...