Panasonic TH-42PZ77U SC board repair 7 blinks

[tom66]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

Yes, looks possible to recover, you just need to get some solder on that pad, make it as even as possible, then stick the new FET on. If you can't get solder to flow, make sure there's an electrical connection and then consider adding an additional heatsink to the FET (the board is used as a heatsink.)

[Rockguy]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

Yes, looks possible to recover, you just need to get some solder on that pad, make it as even as possible, then stick the new FET on. If you can't get solder to flow, make sure there's an electrical connection and then consider adding an additional heatsink to the FET (the board is used as a heatsink.)

Thank you very much for the replies. I wonder if this would work? http://www.ebay.com/itm/151506956163...%3AMEBIDX%3AIT

I also saw in another thread I "think" from you about maybe using a copper sheet?

Additional heatsink is a nice idea. I'll have to look for something that would be suitable for this

[tom66]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

I wouldn't use that. There's still most of a pad left there so I'd solder to what you have left; if you can't get all the solder to flow, then add something like this afterwards:
http://www.ebay.com/itm/3pcs-Brand-N...item2ed4058859

(One of those is about the right size)

[Rockguy]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

I wouldn't use that. There's still most of a pad left there so I'd solder to what you have left; if you can't get all the solder to flow, then add something like this afterwards:
http://www.ebay.com/itm/3pcs-Brand-N...item2ed4058859

(One of those is about the right size)

OK thank you Tom. I see that is from China. I wonder if my local radio shack might have something? Maybe a US seller on ebay. Might take forever getting something from China

[tom66]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

Yes, you could also look on a scrap motherboard or sound/network/graphics card, etc. To be honest those FETs don't run very hot in operation and there are 6 in parallel so you would probably be ok. I guess worst case it fails again and you have to replace the FET again, the failure usually doesn't damage other things.

[Rockguy]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

Yes, you could also look on a scrap motherboard or sound/network/graphics card, etc. To be honest those FETs don't run very hot in operation and there are 6 in parallel so you would probably be ok. I guess worst case it fails again and you have to replace the FET again, the failure usually doesn't damage other things.

Good advice. I didn't think about that. I will see if I can flow enough solder. I bought 3 FETs so I have a couple extra in case.

[Rockguy]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

The solder will only flow where the old solder still remained. The area where the board was torn out it will now stick to.

[ryanfan03]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

Hi guys. Thanks for the advice from this thread. I found a bad FET and lifted both legs from the board and plugged it in to see if it powers up. Unfortunatly, now I get 10 blinks. I disconnected the SC board again and the blinking stoped. I plugged in just the top connector SC2 and no blinking. Only when I plugged in the bottom connector (SC20) did the 10 blinks start. I think I followed this to the tuner board (DG?). Does this probably mean that the DG board is dead?

[Rockguy]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

The solder will only flow where the old solder still remained. The area where the board was torn out it will now stick to.

Well I decided to just solder the new transistor in to what was remaining on the board and it seems to be working for now. The FET tests fine just like the rest of them now. Thanks to everyone that helped with this. If I have to do this again, I've learned I really need to make sure the entire area is heated up and the FET comes off easily.

[BillyG]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

Hey guys, sorry for digging up an older thread but having a bit of a problem.
Found my way here after a Goggle search on my TH-42PZ70BA with the 7 red flashes of death. Hopefully this great thread will sort my problem....Or so I thought.
Ordered a few 5N2307's which took nearly 2 weeks to get to me. Good old fleabay.
Stripped the back of the TV with no probs and dug out the old trusty Weller PU-2D to start lifting legs on the on board chips to test them on my meter. Unfortunately, the Weller wouldn't even melt the solder. Looks like they're welded on.
Doesn't help when I find my old eyesight is getting that bad, I had to use a magnifying glass to check things. Trip to the opticians today cost me £350 for new specs.
Also couldn't find my old solder sucker, so nipped down to the local Maplins to find the only way to get one was to buy the kit which included a 40w iron and some solder. Didn't have the single sucker in stock but for a fiver more, I got the whole kit for £14.99. This also didn't even look at the solder.
My question to you guys is how or what do I need to get the solder problem sorted out ?
Thanks in advance.

[tom66]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

Much more heat, I'm afraid. I've got a 60W regulated iron, and that even struggles. You might have to use a hot air gun, or consult someone with a more powerful soldering iron. Please note that too much heat is bad and could damage the PCB traces, so don't try using a paintstripper or something like that.

[Rockguy]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

Hey guys, sorry for digging up an older thread but having a bit of a problem.
Found my way here after a Goggle search on my TH-42PZ70BA with the 7 red flashes of death. Hopefully this great thread will sort my problem....Or so I thought.
Ordered a few 5N2307's which took nearly 2 weeks to get to me. Good old fleabay.
Stripped the back of the TV with no probs and dug out the old trusty Weller PU-2D to start lifting legs on the on board chips to test them on my meter. Unfortunately, the Weller wouldn't even melt the solder. Looks like they're welded on.
Doesn't help when I find my old eyesight is getting that bad, I had to use a magnifying glass to check things. Trip to the opticians today cost me £350 for new specs.
Also couldn't find my old solder sucker, so nipped down to the local Maplins to find the only way to get one was to buy the kit which included a 40w iron and some solder. Didn't have the single sucker in stock but for a fiver more, I got the whole kit for £14.99. This also didn't even look at the solder.
My question to you guys is how or what do I need to get the solder problem sorted out ?
Thanks in advance.

So you have actually identified the bad transistors? How many bad ones are there? Like tom said, it takes a lot of heat. Don't try and pry on it either. You have to get it hot enough that it easily comes off or, you have the same problem I had which you can see on the previous page. Luckily I was able to solder the new one on and it works fine but, I still don't want to see it happen to you. Heat the heck out of that back tab.

[BillyG]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

Thanks @ tom66. Certainly seems like I'll have to invest in more suitable equipment.

@ Rockguy - Nope, can't get as far as identifying the problematic ones as I can't get enough heat into the solder to lift any legs to check them.
Hopefully and with everything crossed, when I manage to get something with a bit more heat power, it's the most common problem on the 5N2307. Certainly, with most of what I've read around the interweb. I bought 3 just in case.

[Rockguy]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

Thanks @ tom66. Certainly seems like I'll have to invest in more suitable equipment.

@ Rockguy - Nope, can't get as far as identifying the problematic ones as I can't get enough heat into the solder to lift any legs to check them.
Hopefully and with everything crossed, when I manage to get something with a bit more heat power, it's the most common problem on the 5N2307. Certainly, with most of what I've read around the interweb. I bought 3 just in case.

OK, let me tell you about my experience. I did not lift the legs of all of them to test. I tested everyone with the legs intact first. I recorded my findings on paper.

My problem was in the Q 641-646 bank. Reading around here, others seem to have the same area so start there.

Have a look at the thread I started. You will see my measurements in post #8. Again, those were taken with no legs lifted. The .045 is a red flag on that bank. I then found that Q644 the left leg measured lower than the rest. .319 as compared to .386. I then lifted the leg of that transistor and voila, the others returned to a much higher level. Q644 was my bad one.

Now, I didn't need much heat to lift the leg. I was prying on just the leg while heating with a little pick tool. Be gentle and you should be fine. It's the base of the transistor itself that needs a lot of heat and care to get loose. One little leg should be fairly easy but, like I said, take measurements in circuit first so you don't have to unsolder a whole bunch of legs unnecessarily.

If you have any questions, fire away. I'm no expert as you can see from my thread but, I can help with the procedures I went through. The TV I fixed is still working

[BillyG]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

Thanks for the tips Rockguy.
I did try them onboard but all readings were the same. Although, I didn't check between S & G. Only between the centre pin and S & G.
Got a bit more checking to do then lol.
Great pointers though and many thanks for the help.

[BillyG]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

Sorry for double post but unable to edit above one.

Right, done some more testing onboard as suggested and possibly can rule out this board.

TNPA4250 SC Board
Tested all 5n2307's and all banks seemed OK with meter going through all possibilities.
Q641-Q646 All equal
Q695-Q696 All equal
Q648-Q654 All equal

However....I did notice that board TNPA4251 SS at opposite side of TV also had 5n2307's. Tested Q101,Q102,Q105,Q106 and all were equal.

But....next to them were a group of 3 5N2007's
Q111 which had a slight mark on top as well - Tab - G no reading at all....Tab - S 0.511 meter bleeps....G - S 1.772
Q112 & Q114 G - S Reading keeps rising on both of them. 1.2xxx and rises
Tab - G keeps rising as well.

Have I found the problem with Q111 ? Is it bringing the other two down ?
If it is these, any ideas where I can source them in the UK. Can't find any on Ebay.

Thanks in advance for any replies

[tom66]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

7 blinks can also be SU/SD boards; To verify this disconnect the boards (the Y-buffer boards, SU and SD) and power on the set. They only need to be disconnected from the SC board. You can leave the orange panel ribbons attached. If you get no more blink code (you won't get a picture) this could be an indication of a bad plasma panel unfortunately (the panel kills the SU & SD.)

[BillyG]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

Thanks for the input again tom.
Done as you suggested and still get the 7 blinks. So hopefully not a bin job yet

[BillyG]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

Scratch that. I forgot I had one of the leads disconnected to the SC board Fired it back up with the omitted cable connected again and the SU and SD boards disconnected and I get a solid green.
Is this a definite uneconomical repair now, or did my weird readings on the SS board have anything to do with it ?

[tom66]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

It's not good. It is possible the buffers are just bad on their own. They do sometimes just fail. However, there is a known issue with these panels killing the SU and SD boards due to a manufacturing defect in the earliest 7G Panasonic FHD plasma panels (especially the 42" ones, like this.) I notice the SU/SD are about £20 each so maybe worth the risk if you want to try it. The problem is, if the panel is bad it'll kill the board(s) again.

You could try with just one buffer at a time. You may get a partial picture in some cases.