Panasonic 7 Blinks Enigma

[ranergeo]

Hi! I have a Panasonic TCP42C2 Plasma tv I've acquired with a 7 blink code. Following the Panny 13th gen troubleshooting guide (actually for the S2 series, not the C2), it brings me to the SN board. Unlike most of their tv's, the SN is a full Y-sus/Ybuffer combo, with no way to separate the sus from the buffers. Replacing the SN board with one tested good resulted in a continued 7 blink code. Dead end #1. Upon further searching, some forums mentioned the A board mis-processing the diagnosis signals sent from the SN board, resulting in a false code diagnosis. So, I replaced the A board, but again, no success.

So, with the service manual and a schematic, I've tried to nail down the cause of the problem. The service manual says the 7 blink SOS code is caused by a SN connector DET or SN scan and logic IC (can anyone tell me what a connector DET is??), while the troubleshooting guide says the diag chip is looking at the floating ground along with VScan, 15V and 5V signals on the SN board. All voltages are present at the SN board, but on looking at the diagnostic send to the A-board, I find a high voltage output kick in right before it goes into shutdown, which I figure to be the logic chip on the SN board reporting a problem in a voltage circuit.

Has anyone else had this type of problem with this tv before I go too nuts trying to find it ? I can probably post some schematics upon request! Thanks for the help!

[randtek]

Re: Panasonic 7 Blinks Enigma

Probable SS Board issue, requires software upgrade to prevent repeat failure. What is the part number of the SN board you replaced?

[ranergeo]

Re: Panasonic 7 Blinks Enigma

It's a TNPA5066AB board if I remember correctly (I'll double-check when I get home, but am almost certain it was his one).

I did read something about applying the software update, but didn't know how I'd be able to do it considering the set went in to safe mode moments after turning on, so I'd not be able to do it through the on screen menu. Does the update process before the set goes through the diagnostic?

[randtek]

Re: Panasonic 7 Blinks Enigma

You will have to fix the TV before you can update it.

[tom66]

Re: Panasonic 7 Blinks Enigma

Randtek, is this a known problem with Panasonics? Software bug blows up SS? I had a TC-P50G10B that had 7 blinks too. Maybe it was the SS and software bug. If only I had not cracked the damn panel.

[ranergeo]

Re: Panasonic 7 Blinks Enigma

I just double-checked it, and it is the 5066AB SN board.

There were some checks for resistance values at various points across the board (in the troubleshooting guide) which did check out ok, but since I can't isolate the SC from the SU and SL boards, does anyone have any ideas on where to look for the failure when there are no visible problems on the board? Is there anything common that goes bad on these boards that I can use as a starting point? Also, would disconnecting the panel connectors from this board isolate out the panel (since the panel is a rare problem to cause this code)?

Also, would a 5066AC or AD board be compatible with this board, or is the suffix critical for compatibility? Thanks!

[IamCanadian]

Re: Panasonic 7 Blinks Enigma

From what I see only the AB suffix can be used.

But also I would suspect the SS, Check for shorted fets.

[ranergeo]

Re: Panasonic 7 Blinks Enigma

I checked all the FET's on the SN and SS boards, and using the ohmmeter test found on site, all checked out as o.k. It took me a bit, as I had some of the diodes confused with the FET's (D'OH!). Any thoughts on next steps?? The previous board I had purchased had the "AC" designation, which the seller stated as compatible (I was able to return it when it didn't work). Would it be best to purchase the correct replacement board, or continue testing this one?

[tw2005]

Re: Panasonic 7 Blinks Enigma

So you sent it back and only have the original suspect board? pity I would have done a bit more testing with it first.

With it all hooked up, i'd try back probing the VS connector SN2 on the SN board or P2 on the PSU and switch it on and see if there's any voltage even only briefly. looking roughly 190-200V.

It's not impossible that both may be faulty. it's happened to me being sent a board also with a fault.

Looking at Shopjimmy it suggests the AC is also compatible with the 42C2.

[ranergeo]

Re: Panasonic 7 Blinks Enigma

Yeah, I'm learning all kinds of things as I go along ! But I did check the Vsus at the SN board, and did get 195V before I heard the click and it slowly started to drop. I also had the appropriate 15V and 5V from the A board which is supposedly used to test the circuit as well.

I did notice that Shopjimmy said the AB was forward compatible for the AC board, but when I looked at the AB board, it said "no known compatibles". Is that possible (only forward compatible and not backwards)?

[tw2005]

Re: Panasonic 7 Blinks Enigma

Shopjimmy does not have all the answers but if you look a bit deeper into the info with that part number you'll see both are attached to panel# MC106H30U13

So i'm pretty confident it'll be fine. I've been in the same situation unable to find the exact revision with nobody having any idea whether others would work.

So I took a punt on 2 different versions and came up trumps with both working as replacements. (TH-P50V20A)

How confident are you that you've check all the FETS,IGBTs and diodes as no shorts?

Have you by any chance checked the resistance accross the connectors on the SN or SS boards?

I do have a radical idea but I'm thinking of disabling the SOS on the SN but removing the safeguard has it's risk of maybe some smoke out of the board however if that does happen it was probably faulty anyway.

i have done this twice now on other SC boards i could not find any shorts on which helped me out.

The only concern i have is the SN3 - SS3 connection and maybe damaging the SS. And if the panel is shorted, will the SN buffers also fry??

I have not worked on one of these new combined SC,SU,SD setups.

I have seen a video of someone completely disconnecting SN3,SN2 & SN20 and have the set go to SOS6 and then replacing the SN ending up all fixed.

have you read this? https://www.badcaps.net/forum/showth...npa5066&page=3

i don't see a result but it has a TNPA5066 SN board.

And this https://www.badcaps.net/forum/showth...light=tnpa5066

Which had SOS4 , shorted SN TNPA5066

there may be some isolation tips and results which you could perform to compare results.

I guess the other here is i think you mentioned possible bad panel, still worth considering since you've tried 2 SN boards. I'm not sure there, never tried testing a panel and I'm not sure what happens when you fire up the SN removed from the panel either.

[ryan74]

Re: Panasonic 7 Blinks Enigma

Does this model have the jumper at sc50, or maybe sc20. Bottom left on sc board?
If it does REMOVE su,sd boards and use something to jump sc50.
It should power up. Mine had blue status led on sc and ss.
If it does power up normally you have a bad su, sd, or panel
This may help isolate your prob

Turned out I had a visible short in the panel I could only see after removing the tinted cover glass

[tw2005]

Re: Panasonic 7 Blinks Enigma

Does this model have the jumper at sc50, or maybe sc20. Bottom left on sc board?
If it does REMOVE su,sd boards and use something to jump sc50.
It should power up. Mine had blue status led on sc and ss.
If it does power up normally you have a bad su, sd, or panel
This may help isolate your prob

Turned out I had a visible short in the panel I could only see after removing the tinted cover glass

I don't think so. It's an all in one assembly, SC,SD,SU in one board.

Missed your post, bad luck with the panel. We smoked that board but at least you can lay the poor thing to rest.

[tw2005]

Re: Panasonic 7 Blinks Enigma

Manual if you have not found it yet.

[ranergeo]

Re: Panasonic 7 Blinks Enigma

tw2005 - As far as the IGBT's and MOSFET's go, I did the simple resistance tests for FET's found elsewhere on site, but did not go as far as remove them from the board to fully test operation. Should I do this? I didn't find any shorts, but again, it was a quick on-board test. The diodes tested fine.

One thing to add is that I could get the tv to remain on when SN20 and A34 (and/or A33) were disconnected, so I was able to confirm that the SN operation LED would turn on and remain lit. In this case it held full VSus voltage, but was now missing the 15 and 5v sources provided by the A board.

I have also done the test to isolate the SN board by disconnecting the three input connectors and reading the SOS code. It changed to 6 blinks, which Panny says indicates a bad SN (which led me to the SN purchase originally). I have also powered on the tv with the SN to panel connectors disconnected with no change, although I have not tried the same test with the SS board. What would happen if I tried?

I haven't tried the bulb test to VSus output yet, but figured that since the LED remained lit w/ the A board disconnected (and voltage remained stable on DMM), Vsus must be ok.

I will try to do some further testing on the SS board by disconnecting P11 (I did it once, but have now forgot the result!). Should I try leaving the SS to panel connectors off, or will this damage the board?

Ryan74 - there are no jumpers on the SN board

Thanks again for all the help!

[tw2005]

Re: Panasonic 7 Blinks Enigma

it should be ok connected but maybe try disconnected first. I just got to have a look at A33/34. Puzzled with Tv on and SN20 disconnected and set on. I would have expected SOS6?

Something that has happened to me was an undervoltage on VAD but I'd have to have a look at the CCT I don't think it's on this board anymore, guessing without reading first but in my situation when I disabled SOS7 on that board i got the TV to produce a picture which is what I'm thinking with yours.

I'll see if I can work it out. At this stage I'm ruling out PSU,A board and I don't think the SS is it either.

[tw2005]

Re: Panasonic 7 Blinks Enigma

can you do whatever you did to get the SN to power on and locate TPVAD, not far from SN20 and measure it please.

[tw2005]

Re: Panasonic 7 Blinks Enigma

The SN20 A33/34 was that to try and get an 8 blink?

[tw2005]

Re: Panasonic 7 Blinks Enigma

Try also disconnect of SN20 & C10 on the C1 board. everything else connected. Hoping to see 8 blinks.

[ranergeo]

Re: Panasonic 7 Blinks Enigma

o.k., I reconnected all the boards, leaving A20 and A34 disconnected (allowing the tv to remain on), and the reading at TPVAD was -190.7 VDC

The removal of the cables was just something I found at the end of the troubleshooting guide when testing previously, as I just wanted to see if I could get the set to stay on. It partially led me to think the A-board was reading the SOS7 circuit incorrectly, but further investigation showed me that the SN board did, in fact, send a high (I got about 4.5 VDC) signal to the A board moments before turning off. I know this points to the SN, but I don't want to purchase (again) something that might not be the root cause only to have to pay for restocking and postage... that would be a real .

Interestingly, the 13th Gen troubleshooting guide says that the three connectors will only leave a blank screen, but leave the tv on, which was all I was aiming for.