Panasonic Viera TX-P42S21B - 7 Red Flashes

[Paft]

My Panasonic Viera TX-P42S21B 42" 1080p HD Plasma developed a fault a few days ago.

It looks like it's going to come on, makes that click sound but then goes off. Doesn't turn on via remote.

So, obviously it's likely one or more of the components/boards. I don’t see any results for my model or a service manual anywhere, but I’ve briefly looked into it with similar models and apparently it is the SC and or SM board(s.)

How accurate are the fault blink codes? I don’t see any glaringly obvious damage on the SC/SM boards but the power supply has some markings. See images. Could the PSU be the original issue, causing this instantly happen again if I replace the SC/SM? Or am I correct in saying when an SC/SM goes bad it can take out the PSU too? How do I correctly diagnose everything?

I briefly spoke to a couple of part sellers, since they advise asking questions before buying.

Answers:

I asked the same slimmed-down question as this thread to two sellers. The first on a listed power supply and the second on a listed Y-SUS.

A) Hi, I have been advised that is a Y sus issue i am afraid. Many thanks, […]

A) […]Hi, yes this board will do but the fault can also indicate a problem with the X-SUS board and or the Buffer board too.Thanks[…]

They never brought up the marking on the PSU.


I don’t have a multimeter to hand and I’m a novice anyway. But I have ordered one for Sat. I will be looking more into it over the week until it arrives but any info/help would be greatly appreciated.

Video of fault:

https://youtu.be/cSnk7HWk38E

[dick_barton]

Re: Panasonic Viera TX-P42S21B - 7 Red Flashes

T200 looks as though it has soot around it. What is the underside of it like. (underside of the board).
There's not alot you can do without a meter available.
Use your new meter when it arrives set to diode mode to check D207

[tvtimmy]

Re: Panasonic Viera TX-P42S21B - 7 Red Flashes

First thing to check is a short on the sc board connector going to the power supply. Unplug it and check it in continuity mode(beeping meter sound). If you find one or some, remove the 4 screws that attach the SM board to the SC and check again. A beep that lasts longer 5han 6 seconds means a short. Reversing the leads will give a beep of about 3 seconds, that's just from the capacitors charging up. If no beep, check the SM board for shorts. Place one lead on one of the 4 ground holes (marked in red) and rake the other lead across each ribbon connector.

[Paft]

Re: Panasonic Viera TX-P42S21B - 7 Red Flashes

Thanks for the replies.

-How do I correctly test the SC board?

-I get a continuous beep on the SM board on several of the SM6 ribbon pins. They look like they go to the fourth IC(?) chip from the left.

-I get a continuous beep on D207 on the power supply where the black marks are. I don't see anything obvious underneath. (But it's rather grey in England and getting dark. I had to use flash. I'll take some again tomorrow)

Attached are images of the bottom of the PSU and the SM or: https://imgur.com/a/vI5Geh9

[dick_barton]

Re: Panasonic Viera TX-P42S21B - 7 Red Flashes

D207 looks as tough it could be across a transformer winding so would need to be checked by lifting one end of the diode from the board.

[tvtimmy]

Re: Panasonic Viera TX-P42S21B - 7 Red Flashes

Your SM board is bad. Take out the 3 screws that hold it in and unlatch the 3 connectors going to the SC board Flip it over, with the ribbon connectors still attached to the panel, over to the outside of the tv. On the SC board you have to short the 2 pins of SC50. I use a thick paperclip. Turn on the tv and check if the green led on the SC is lit. Don't run the tv for more than 20 seconds! Green led means the SC is good. Do this test before messing with the power supply diode.

[Paft]

Re: Panasonic Viera TX-P42S21B - 7 Red Flashes

Thanks for the replies again.

Following you, steps, tvtimmy-- I turned it on for around 3 sec. I get a green light on the SC board.

Does every board have a green LED? Where do I go from here? Do as dick_barton suggested?

[tvtimmy]

Re: Panasonic Viera TX-P42S21B - 7 Red Flashes

Now you have to buy a SC. Board. I would replace the mounting screws for it and the SC mounting screws with the new ones with the lockwashers.

[Paft]

Re: Panasonic Viera TX-P42S21B - 7 Red Flashes

I know it's very difficult on your end to diagnose things you're not even in front of.

"Now you have to buy a SC. Board." Did you mean SM board? The one that the ribbons connect to?

Is this a bit of a guessing game now or do you think the new SM board will solve it? The SM board is a good price but the other bits start adding up.

Why do the screws need replacing? How do I know exactly what to get? I don't have a calipar.

[tvtimmy]

Re: Panasonic Viera TX-P42S21B - 7 Red Flashes

Oops! I meant SM board. Your SC is ok.
Shopjimmy.com sells them. The old ones don't have lock washers and they loosen up over time.
That's what caused your tv to go out.

[Paft]

Re: Panasonic Viera TX-P42S21B - 7 Red Flashes

Cheers. I assumed that and I ordered one for £16.99. Estimated delivery Thu, 29 Oct.

Fingers crossed. I'll update once arrived/fitted.

Board failure from the screws? That's ridiculous. Edit: Just an FYI all the screws I've removed have been have had lock washers as fair as I can tell.

[tvtimmy]

Re: Panasonic Viera TX-P42S21B - 7 Red Flashes

When you fit the ribbons and turn on the tv, you will probably see lines going across the screen. Turn off the tv before you readjust them. Take your time, It still takes me 5 to 25 times before I get them all perfect.

[Paft]

Re: Panasonic Viera TX-P42S21B - 7 Red Flashes

Well, it was definitely the SM board.

Sadly part of the right side of the screen is blank/missing.

I will point out that the part I got was "identical" part number wise but it was from a TX-P42S20BA instead of TX-P42S21B. I chanced it thinking a part is a part. Is that the problem? If that's the case I guess I am one of those annoying customers on eBay. I'll keep it and sell it dearer.

Edit: I've ordered Panasonic 42" TX-P42S21B TNPA5086 AC 1 SM Buffer Board Free Tracked P&P

[Paft]

Re: Panasonic Viera TX-P42S21B - 7 Red Flashes

Appologies if double posting isn't allowed but editing has a time limit.

Attached are images.

I noticed they do differ slightly-- extra or missing components. I assume I've answered my own question?

Am I alone in thinking it's an odd way to work? Same part numbers but they're not...

[tvtimmy]

Re: Panasonic Viera TX-P42S21B - 7 Red Flashes

That board controls horizontal lines across the screen. Check the ribbon latch on the bottom buffer board directly under the SM board. Those bottom buffers control vertical lines of the screen.

[tvtimmy]

Re: Panasonic Viera TX-P42S21B - 7 Red Flashes

Check this ribbon latch.

[Paft]

Re: Panasonic Viera TX-P42S21B - 7 Red Flashes

Thanks. I already cancelled that order, after finding a £6.38 SM board. That hasn't been dispatched yet. Should I cancel it?

Is there a specific method to test the bottom buffer boards? I assume that's a faulty bottom buffer too?

I reseated the ribbon you mentioned twice. Although that's the first time I've touched it. No change.

[tvtimmy]

Re: Panasonic Viera TX-P42S21B - 7 Red Flashes

I don't know a way to test them. Are you missing the last part of the display on all inputs?
There is a way to reverse the image on the screen to see if the mainboard is a problem, but I can't remember how.

[Biruslapio]

Re: Panasonic Viera TX-P42S21B - 7 Red Flashes

The ribbon cable that goes from the mainboard to C-Board left side(facing the TV backwards), try reseating that one.

[Paft]

Re: Panasonic Viera TX-P42S21B - 7 Red Flashes

Well, I call tell without anything actually connected because the AV source option box is cut off for example. As are any other screen or menu that takes up that area. I'll test all inputs for the hell of it though.

Thanks for your help so far.

edit: Didn't see you post Biruslapio--looking now. I will point out that nothing has been touched before besides the power supply and buffer board(s.)