Panasonic TC-P42G25: No Power with 4 LED Blinks

[TheTVCoop]

Hi,

I had a previous customer come to me for help with a broken TV he got for free on Craigslist. When the power button is pressed the LED blinks 4 times, pauses, and repeats. From what I've read online it's likely a problem on the SC board. I read of one vague instance of this being repaired via replacement components, but most opted to replace the whole board.

Would anyone be willing to guide me through how to verify the problem is on the SC board, and then maybe help find the component to replace?

Much Appreciated,
Cooper

[tom66]

Re: Panasonic TC-P42G25: No Power with 4 LED Blinks

4 blinks not SC fault.

Follow this guide (different TV, same procedure):


(in particular, page 67.)

I will try and find the exact training manual for your set and upload it.

[tw2005]

Re: Panasonic TC-P42G25: No Power with 4 LED Blinks

I have a copy but too big for upload.



Just had a quick look at the layout of it. Same SC PCB TNPA5081 but different version to the 50" I just fixed with 4 blink.

It can be the SC if it has had a massive failure and shorts the PSU which will show as 4 blink.

Disconnect the SC SC2 connector and see if you still have 4 blink. Can be 200Volts on that so don't let it earth out on the chassis.

If it goes to 7 blink then SC,SU,SD. Most likely SC though.

If still 4 blink try disconnecting SS11 on SS board and see if it changes. Same deal voltage wise.

This was my post for the 50" 4 blink which may give you some help.

https://www.badcaps.net/forum/showth...4+blink&page=2

[tw2005]

Re: Panasonic TC-P42G25: No Power with 4 LED Blinks

I meant to also mention that component level can be fun but generally I found a lot of the transistors were panasonic and virtully impossible to find or get data on (SC board).

There's a couple of cheap SC boards in the UK which should suit should you need 1.

just remember the 42" and 50" boards are the same PCB but distintive differences with components.

Some sellers will just list it as TNPA5081 so look closely.

I got mine landed in Australia $50AUD all up!

[tw2005]

Re: Panasonic TC-P42G25: No Power with 4 LED Blinks

Here's some examples, 42,46,50,54 left to right

[tom66]

Re: Panasonic TC-P42G25: No Power with 4 LED Blinks

The lower screen size versions are just cut down because they don't have to drive such a large plasma panel. In theory, you should be able to get away with a larger screen size board in a smaller model -- don't quote me on this though, there may be other differences.

[tw2005]

Re: Panasonic TC-P42G25: No Power with 4 LED Blinks

The lower screen size versions are just cut down because they don't have to drive such a large plasma panel. In theory, you should be able to get away with a larger screen size board in a smaller model -- don't quote me on this though, there may be other differences.

I'd love to test the theory. I was thinking the same.

[TheTVCoop]

Re: Panasonic TC-P42G25: No Power with 4 LED Blinks

Thanks guys. I'll see if I can test some of this out tonight, but then I'm out of town a few days. I'll let you know what I find.

Thanks,
Cooper

[TheTVCoop]

Re: Panasonic TC-P42G25: No Power with 4 LED Blinks

OK, I finally got around to checking this out. Forgive me; I've been working on selling my house.

ANYWAY. I unplugged SC2 and got 7 blinks. I'll be reading through the manuals but thought I'd throw that out there in case anyone had direct advice on what to do next.

Thanks again all!

[tw2005]

Re: Panasonic TC-P42G25: No Power with 4 LED Blinks

OK, I finally got around to checking this out. Forgive me; I've been working on selling my house.

ANYWAY. I unplugged SC2 and got 7 blinks. I'll be reading through the manuals but thought I'd throw that out there in case anyone had direct advice on what to do next.

Thanks again all!

Did you not read my post which gives you a linkto my fault finding for this very scenario?

The fact it changes from a SOS4 PSU fault to SOS7 tells you it's not the PSU.

Follow what I did. Hook up your meter to the VS line on the PSU and power up. You should see a couple of hundred volts briefly.

Most likely you have a shorted SC board. Bell out the diodes and FETs on the SC board. I'm confident you'll find some shorted out.

[TheTVCoop]

Re: Panasonic TC-P42G25: No Power with 4 LED Blinks

Sorry tw2005. I got excited and I guess I jumped the gun on posting a reply. I skimmed through the post you linked but honestly, didn't understand some of it. I'll read it more thoroughly and do what I can before posting again.

For what it's worth, don't let the member name fool you. I sell TVs for side income, not repair them. Although I'd be interested in being able to do both... eventually. Be easy on me, and I'll be more diligent about being more thorough before posting.

Thanks,
Cooper

[tw2005]

Re: Panasonic TC-P42G25: No Power with 4 LED Blinks

Same. I do it as a side hobby because I don't get much "real" electronic repair work with my job.

Post 23 is a summary but you could ignore the SOS6 because that was because I was supllied a dud board but very interesting read none the same.

In a nutshell a working SC board fixed my SOS4 and as stated previous same TNPA5081 excepting some variation in components between the 50 & 42

[TheTVCoop]

Re: Panasonic TC-P42G25: No Power with 4 LED Blinks

OK tw2005, I've read your post several times... forgive me for not understanding it completely. Any chance you'd be willing to walk me through the steps in layman terms? I'll understand if that's too much work.

In case it helps to know what I'm working with...
Mechanical engineering degree, 2005; limited electrical engineering
GQ Electronics 5200 rework station
GQ-4X USB programmer
Sperry 4100A multi-meter
and hopefully a lot of advice, haha

[TheTVCoop]

Re: Panasonic TC-P42G25: No Power with 4 LED Blinks

I should have mentioned, I know you said to ignore the SOS6 from post 23, which I think means the LED mentioned, but I definitely do not have a lit LED in that location on my SC board. Any chance I could be so lucky as to that being my issue too? I'm not sure how to test the other components mentioned in your first post. I can find them, but don't want to risk damaging something by just probing around aimlessly.

[tw2005]

Re: Panasonic TC-P42G25: No Power with 4 LED Blinks

I should have mentioned, I know you said to ignore the SOS6 from post 23, which I think means the LED mentioned, but I definitely do not have a lit LED in that location on my SC board. Any chance I could be so lucky as to that being my issue too? I'm not sure how to test the other components mentioned in your first post. I can find them, but don't want to risk damaging something by just probing around aimlessly.

No you're not that lucky. If it was only the LED you'd have SOS6. The SC is shorted hence the PSU SOS4.

You could check the buffers for shorts. It's one thing I'm not that sure with.

Maybe someone else here can help there.

For me I don't think you need to do much else other than get a SC.

[tw2005]

Re: Panasonic TC-P42G25: No Power with 4 LED Blinks

Here's a training manual. It might have some procedures for you.

I'm not an expert so i only know what I've read myself.

It's actually on the 42S2 which will make it easy for you to follow as it'll be very close to your G25.

[TheTVCoop]

Re: Panasonic TC-P42G25: No Power with 4 LED Blinks

Thanks tw2005. I'll let you know if the owner decides to buy the board and give it a shot.

[TheTVCoop]

Re: Panasonic TC-P42G25: No Power with 4 LED Blinks

So the owner does want to replace this board. I know you cautioned me on making sure I get the right one. This looks like the correct one to me. Would you agree?

http://www.ebay.com/itm/PANASONIC-TC...item2ec33851f7

[tom66]

Re: Panasonic TC-P42G25: No Power with 4 LED Blinks

I'm not tw2005 but it looks right.

PayLess Components? What a rip off... Try offering a lower price, first.

[TheTVCoop]

Re: Panasonic TC-P42G25: No Power with 4 LED Blinks

Thanks tom66. I'll see if we can get it any cheaper, haha.