Panasonic TX-50EX700B Won't Power On

[oldschoolgamer]

Hi. I have a Panasonic TX-50EX700B which hadn't been used very often for some time. Recently it started getting used a little more often, until one day it just refused to power on with the red LED blinking 13 times. Upon researching, it turned out it apparently had something to do with the 5v power line, so I assumed it was probably the power supply.

I purchased a power supply for the TV from a seller that claims that it works fine and was just taken from a TV with a broken screen. After fitting the new power supply and trying the TV, I was greeted with the power LED being red for a few seconds, then going out, and a few seconds later it would be red again. This cycle would repeat a few times, but it's completely random as to how many times it flashes. It eventually just becomes solid red, and pressing the power button on the remote does nothing other than make the red LED flash, showing that the TV is responding to the remote. I also tried putting the old power supply back in and it has the same result now as with the new power supply instead of the 13 blinks.

It seems most of the red LED codes are SOS codes, but this one doesn't even seem like an error, since it's random as to how many times it flashes on and off (really slowly, like about 2 seconds on, 5 seconds off). Does anyone have any idea where I should start when it comes to diagnosing the issue? I don't mind too much if the issue wasn't actually the power supply because it didn't cost too much anyway.

[nomoresonys]

Re: Panasonic TX-50EX700B Won't Power On

can you post some straight on clear pictures of each of the boards and one of the whole back, as to see how they are all connected.

[oldschoolgamer]

Re: Panasonic TX-50EX700B Won't Power On

can you post some straight on clear pictures of each of the boards and one of the whole back, as to see how they are all connected.

I'll take it apart again tomorrow and take some clear pictures of it. As of now, all I have is this, which probably doesn't help very much at all given it had a flash and looks kind of compressed.

[oldschoolgamer]

Re: Panasonic TX-50EX700B Won't Power On

I tried to take pictures of the boards but I can't do much with the lighting as of now. I hope it's enough to get the idea at least.

[nomoresonys]

Re: Panasonic TX-50EX700B Won't Power On

maybe try some simple things first, unplug tv for 15 minutes, hold power button in on tv for 30 seconds, plug tv back in and try it, if no joy, unplug the wifi module and speakers from mainboard and try it, while testing have nothing else plugged into tv, no hdmi or rca cables etc.

[nomoresonys]

Re: Panasonic TX-50EX700B Won't Power On

next probably try, carefully peel the tape on the tcon metal cove back to get to the ribbon cables, cables probably held down by a black latch that you flip up with finger nail, never force anything, should be rather easy to unhook. You want to unhook one cable then try tv, see what you get on display, then do the other side, so you will have one cable at a time hooked up, best policy is do ALL HOOKING AND UNHOOKING of cables with tv UNPLUGGED from power to avoid any errant surges and such.

[nomoresonys]

Re: Panasonic TX-50EX700B Won't Power On

the pictures are nicely focused, would be great if you had more light.

[oldschoolgamer]

Re: Panasonic TX-50EX700B Won't Power On

Yeah sorry about the lighting not being ideal. I'll try to take more in a better lit environment if need be. I'll try the other things you mentioned too though and see how it goes. Thanks.

[oldschoolgamer]

Re: Panasonic TX-50EX700B Won't Power On

Hi again. I have finally gotten around to disassembling this set again to have a look at it, I don't have a lot of room so I have to reassemble it every time lol. Anyway, I'm about to try out the above suggestion, but first, here are some better pictures. Turns out I stupidly had my camera exposure settings wrong which explains the terrible lighting...

EDIT: Having tried removing all of those cables as suggested above, it seems to always do the same thing. The red LED will come on for about 2 seconds, then go out for about 2, and then it will do one of two things; either repeat this LED on and off thing a few times in this same slow fashion, or else just remain solid red afterwards. It seems intermittent as to how the LED behaves but it always results in the same scenario where it becomes solid red, the TV will react to the remote (you can see the red LED flashing quickly), but it won't do anything else other than this, it just remains solid red again.

[oldschoolgamer]

Re: Panasonic TX-50EX700B Won't Power On

ok so upon further inspection, if you leave the TV plugged in for about 15 minutes, it will go through that cycle of slow flashing every 2 minutes or so, and eventually it turns into 13 flashes again. My bad, I didn't realise that it was still the same error code, it just takes a really long time to show up.

[nomoresonys]

Re: Panasonic TX-50EX700B Won't Power On

looks like 13 blinks is a communication error, probably caused by problem with the mainboard, sometimes it can be just a loose connection of cable or such, can try a hard reset, unplug tv for an hour, while unplugged press and hold the power button on tv for 60 seconds, then hold power button while plugging in tv, see if it turns on and acts normal.

[oldschoolgamer]

Re: Panasonic TX-50EX700B Won't Power On

Given the fact that I tried unplugging everything and got the exact same results, I'm reluctant to assume the A board is the culprit. Even when the LED is doing that weird slow flash thing before it shows the error, each time the light goes out, there's an audible click coming from the A board which sounds like a short almost, but it still does it with everything else plugged out other than the PSU and the A board, so I was assuming that meant the A board itself has some sort of short or broken connection. Judging by the fact the board even looks discoloured around the CPU, I think it was likely caused by a heat issue, probably with BGA solder joints like I've seen many times with the infamous RROD on Xbox 360. I guess my chances are to just go with buying another A board with the same specs as this one, given it's extremely likely to be the culprit. It behaves identical with two different power supplies, even with all the cables unplugged to the speakers, wifi module, TCON, etc.

Thanks for the help in trying to narrow it down, I'm hoping just getting another A board will resolve the issue instead of throwing the TV away.

[nomoresonys]

Re: Panasonic TX-50EX700B Won't Power On

Indeed, I think you have it, a replacement main/A board should do the trick, let us know how it goes.

[oldschoolgamer]

Re: Panasonic TX-50EX700B Won't Power On

Will do when it arrives. I'm fairly confident that's the issue after seeing how it behaves. Thanks again for aiding in diagnosing the issue.

[nomoresonys]

Re: Panasonic TX-50EX700B Won't Power On

thanks, never a problem helping decent people like yourself, its the pushy ingrates with the crappy attitudes that make it a pain sometimes.

[kasfamily]

Re: Panasonic TX-50EX700B Won't Power On

Is the TV model listed correctly ? Maybe EXR ?

[nomoresonys]

Re: Panasonic TX-50EX700B Won't Power On

TX-50EX700B: https://www.panasonic.com/uk/support...-50ex700b.html

[kasfamily]

Re: Panasonic TX-50EX700B Won't Power On

https://www.panasonic.com/ru/consume...-50exr700.html
It's probably the same model

[oldschoolgamer]

Re: Panasonic TX-50EX700B Won't Power On

Yeah it's definitely the TX-50EX700B that I have here. I bought this one in 2017 and my brother basically had it in his room recently only for it to just be like this when he woke up one morning with the flashing red light. Planning to use it myself again if I can get it working. It looks identical to the one above though yeah despite the R in the model.

[kasfamily]

Re: Panasonic TX-50EX700B Won't Power On

For our model, the main board A cost about $230 at the panasonic warehouse.