Panasonic TH-50PX80 killed by lightning strike, help me save her!

[SluggerB]

Yes it's a 17 year old Panasonic plasma!

I was watching TV when there was a huge lighting strike nearby my house that shook the house. When that happened, the picture on the TV froze and the TV wouldn't turn off except by pulling the power cable. Now if you plug in the TV, it seems to turn on (it makes the turn on "clikcs" it always does, the red power light comes on but there is no picture, although I can see the back light around the edges. And the TV doesn't respond to the power button on the remote to turn off, and doesn't respond to the manual power button on the front of the TV to turn off, it only turns off by pulling the power cord.

Odd thing is, the TV was plugged into a surge protector, and literally zero other things in the house had any damage whatsoever. The clock on the microwave didn't even reset. This TV is the only thing that got damaged. So it might have not been electricity but the shaking that did some damage, who knows.

Since there was a picture on the screen when it froze, I know the screen is still good, and it does seem to "turn on" so the power board seems to be working, so Youtube is telling me it is probably the main board? I opened the TV up and nothing on the main board looks out of sorts, no blown chips, no scorch marks or burn marks or anything, but I ordered a used board off eBay anyway and it will be here tomorrow, hopefully that fixes it.

Any ideas on other things to check? I would really like to have this TV still working.

[R_J]

continued from other thread, ... unplugging the tv for a day or two and see if starts to operate normally, based on your description it does seem like A board programming data is corrupt.

[EazyBone]

Surge protector won't ever protect from a lightning strike just fyi. 6.21 gigawatts of energy ain't gonna be stopped by a tiny surge protector. (Thanks back to the future)

[lotas]

If something was connected to HDMI, then the HDMI hub on the motherboard could have been damaged...

[SluggerB]

If something was connected to HDMI, then the HDMI hub on the motherboard could have been damaged...

The TV set up is coax from wall -> cable box > HDMI out from cable box > HDMI to TV. There was also an Amazon Fire Stick in another HDMI port

Thing is both the cable box and the Fire stick are perfectly fine. As is every other electrical appliance in the house. I would imagine if enough power went though either of them to damage the TV, they would have been damaged themselves. The lightning was nearby but not a direct hit on anything.

unplugging the tv for a day or two and see if starts to operate normally, based on your description it does seem like A board programming data is corrupt.

Tried that, nothing. I swapped the cap I thought was bad out of the power board and same behavior, I plug the Tv in and it makes the normal relay click noises it makes when plugging in, I push the power on button on the remote and the TV makes the relay click noise that it makes when turning on, the red light is on at the bottom, I see some glowing and a lighter shade of black on the TV, but no picture at all, no response to the TV from the remote and the only way to turn the TV off is pulling the power cord. I think that means the power board is working and the standby voltage is working at least?

I took the main board out of the TV today and gave it a visual inspection, everything look pristine on it so nothing obviously blew up. We'll see what happens when I put the eBay replacement in later tongiht/tomm, depending on when the FedEx guy shows up

[lotas]

And you touch its case (Analog Devices ADV7495B BSTZ-170), if it heats up a lot, becomes hot, then the problem is in it.

[SluggerB]

And you touch its case (Analog Devices ADV7495B BSTZ-170), if it heats up a lot, becomes hot, then the problem is in it.

I d not understand what you are saying

I swapped the original 1900uf cap back on the power board and reinstalled it. The new main board showed up today and I put that in but th TV till doesn't work. It turns on but I get 12 blinking red lights on the front and no picture on the screen.

[lotas]

I d not understand what you are saying

This is a chip on the motherboard (HDMI hub).

[Ady2017]

I once had a TV killed by a lightning strike back in about 2006. It was an old CRT TV and when I took the back off of the TV a number of the chips had exploded. There was that much energy that it had blown many of the chips into pieces. Like a fool, I left the TV on during the lightning strike to keep my cat calm but the sound of the TV exploding left the poor cat hiding behind the sofa shaking. Everything gets unplugged now. Time to treat yourself to a new TV my friend.

[lotas]

I swapped the original 1900uf cap back on the power board and reinstalled it. The new main board showed up today and I put that in but th TV till doesn't work. It turns on but I get 12 blinking red lights on the front and no picture on the screen.

Error code 12, sound problem....

[SluggerB]

So I disconnected all the wires and ribbon cables to rule out bad connections. Now, instead of getting 12 blinks, I am getting 1. This is with the original Power Board, with original cap, and new Main board. I tried reseating everything again, no dice. TV will turn on with remote press, then turn off and give a 1 blink code forever until you unplug

[SluggerB]

Where can I test that 5V STB to make sure it is there? I see no labeled test points on the power board

https://www.badcaps.net/forum/troubl...80u-no-picture has identical photos to all my boards so that is a reference.

[SluggerB]

OK, so I found .... something

Turns out the 5v STB test points are on the main board, not the Power Board. There are two points by where it is marked. I tested each, and they are reading 3.5v, not 5v. See the picture of the main board with two red circles, that's where I tested.

I followed the wiring where I believe the Power Board is supplying voltage to the Main board, and tested the red wire on that connector. It as well is testing 3.5v. See picture of Power board to see where I tested

Any ideas what could cause that 5v rail to drop to 3.5v?

[lotas]

Service Manual....

[SluggerB]

Well I'm not the best at reading schematics, but Page 30 shows P7 as the STB connection between the power board and the Main board and it should be 5V but I am only reading 3.5. I do not see any 3.5V input to the main board from the power board either. So it seems the power board is outputting the wrong voltage

Edit: I just checked the STB again right now and it is at 2.6 mV. What is going on with this thing?

[lotas]

And what voltage does the power supply supply on the original board produce? Maybe the new board is not working and has a problem with this power supply...

[SluggerB]

And what voltage does the power supply supply on the original board produce? Maybe the new board is not working and has a problem with this power supply...

This is the original power supply. I replaced the main board. The replacement power supply is in the mail but not here yet.

I am hypothesizing that a power surge sent to much voltage thorough the power board and fried the original main board (which is why I got no functioning error messages) then the power board failed and now is not giving correct voltages to the replacement main board.

[lotas]

I meant to put the original motherboard back and what voltage will your original power supply unit produce on the STB?

[SluggerB]

I meant to put the original motherboard back and what voltage will your original power supply unit produce on the STB?

Ahh, gotcha. I will try that in a bit

[nomoresonys]

You need to do testing, remove powerboard, check the underside for anything obvious. here's a few things to check Q151, Q171, D601, D602, D603, D607, D615, youtube is your friend for testing procedures if needed.