Panasonic TX-P42S11B - 7 Blink Code

[Fool2cool]

Hi all, first real TV repair attempt for me!

I have this Panasonic plasma tv on my bench that had the 7 blink code problem, I disconnect the SU and SD boards and still had 7 blink codes, I disconnected the SC board and got 6 blink codes.

And now here's where I messed up big time, I read about testing SC by shorting the SC50 connector with SU and SD disconnected, however I failed to read the part about also removing the VF_GND screws. I promptly turned the TV on and a nice smell of burning greeted me from around the SC50 area.

Testing SC with SC50 shorted AND the screws removed now causes the SC board to sing some very interesting tunes :/

Can anyone tell me what components I'm likely to of released the magic smoke from so I can attempt to get back to my original fault

Thank you
Chaz

[chrishenderson69]

Re: Panasonic TX-P42S11B - 7 Blink Code

hi i am only guessing as i have done the same repair but you may have fried the sc board it might be cheaper to buy a replacement about £40 from flattvparts in portsmouth it might be less than what i paid for mine depending on model etc

Chris

[Fool2cool]

Re: Panasonic TX-P42S11B - 7 Blink Code

Yeah I did consider that, but I'm also worried that the original fault wasn't the SC board, the fault history is that it fell off a stand and onto the floor, so I'm wondering if it could be something like a shorted panel? I don't want to shell out for an SC board if it does turn out to be that although I might have to.

Thank you for the quick reply and advice

[tw2005]

Re: Panasonic TX-P42S11B - 7 Blink Code

When you say tunes, do you mean loud buzzing? Is the board secured with all it's screws.

Second time around did the TV startup with no blinks?

edit: just read the bit about it failing after hitting the floor. I'd be suspect of the panel, may be what blew the buffers/sc and yeah you could end up replacing those to find the panel is broken/shorted.

Don't know how you'd check except obvious cracking?

[Fool2cool]

Re: Panasonic TX-P42S11B - 7 Blink Code

Second time round with the 4 vf_gnd screws removed and SU and SD disconnected the SC board didn't so much buzz as more ring like a dial up modem finishing in a continuous buzz and a solid green light.

Thank you

[tw2005]

Re: Panasonic TX-P42S11B - 7 Blink Code

The boards do resonate especially if not fully mounted up, I have installed SC boards for testing and had the odd one make some weird noises and it's always been due to the pcb resonating but always goes when everthing is mounted including the buffers.


Solid green sounds like it passed startup so the SC is potentially ok. have no answer for the smoke, the buffers would be suspect since you have no blinks, but million dollar question is the panel?

Shorted panels can make weird noises too, and I've only tried fixing one TV to find the panel was shorted, and yeah the noise it made could be compared to a dial-up modem?

Not sure how the panasonic handles bad panels, I'd expect a shutdown and a SOS but with no buffers maybe it can't detect it?

TOM will have a better idea I expect about shorted panel.

That particular SC board like some other Panasonic versions are very hard to find. probably worth more than the broken TV on it's own?

[tom66]

Re: Panasonic TX-P42S11B - 7 Blink Code

Shorted panel will cause SOS6/SOS7 if it kills buffers/SC; SOS8 otherwise.

[Fool2cool]

Re: Panasonic TX-P42S11B - 7 Blink Code

So the fact I get a solid green light with SC50 shorted would indicate that SC is possibly good and SU,SD are blown? But a shorted panel could of caused them to go?

Thank you for all your help so far!

[tom66]

Re: Panasonic TX-P42S11B - 7 Blink Code

You need SU/SD in panel to be certain but if TV was dropped I would be thinking panel is dud.

[tw2005]

Re: Panasonic TX-P42S11B - 7 Blink Code

If solid green is the normal onstate I would expect most likely it's good although I have managed to create a situation during a rebuild of a SC board where it passed, was humming and fired the panel but no drive signal to generate an image due to a faulty octal buffer IC but that was damaged during fault finding the board. I put that as fairly unlikely in your case.

For our models it's flashing green on startup, solid when running, red on standby, blinking red for SOS fault codes.

[Fool2cool]

Re: Panasonic TX-P42S11B - 7 Blink Code

Yeah I get flashing green during startup then a solid green after a short while, I do worry I might of damaged something during fault finding, I'm all set up here to do surface mount rework the problem comes with tracking the fault down as always! Where could I check to see if I was generating a drive signal?

Does anyone have the service manual for this set? I found the service manual for TX-P42S10B but I don't know what the differences would be between the 10B and the 11B that I have.

Also can anyone explain why I had to remove the vf_gnd screws to perform the SC50 test?

Also just had another thought, is it worthwhile removing the panel from the chassis to do a visual inspection? I know someone in a previous thread mentioned that after removing the panel from the chassis and something else from the top of the panel they could quite easily see a crack.

Thanks again

[tw2005]

Re: Panasonic TX-P42S11B - 7 Blink Code

Same SC boards so maybe chassis or mainboard?

[Fool2cool]

Re: Panasonic TX-P42S11B - 7 Blink Code

Hi all, I did some more reading and saw that I should be able to test the buffer boards for a short with a multimeter, I tested both buffer boards. The lower buffer board appears to have a partial short to floating ground on the 4th connector up on 3 pins, it isn't a dead short though, it measures about 4 ohms. Does this mean the lower buffer board is blown?

Thanks
Charles

[tw2005]

Re: Panasonic TX-P42S11B - 7 Blink Code

If you're taliking from gnd - the buffer ribbon connectors, yes it's knackered.

[Fool2cool]

Re: Panasonic TX-P42S11B - 7 Blink Code

I'm talking from VF_GND to the ribbon connectors yes

Thank you for the quick reply

[Fool2cool]

Re: Panasonic TX-P42S11B - 7 Blink Code

Hi all, I replaced the SD board and managed to get a picture up but I know seem to have a panel fault? There is a black horizontal stripe 1 pixel wide which stops just short of the right hand side of the screen and there appears to be an actual mark on the panel at that point when the panel is turned off, it looks like a tiny black fleck. There is also a red horizontal line that intersects the horizontal line where the mark is.

Pictures attached

[tw2005]

Re: Panasonic TX-P42S11B - 7 Blink Code

Well that's a lot further than I expected you'd get. I wonder if it's possible the panel is damaged from impact but all the gas did not escape?

never seen a line stop like that horizontally, normally I'd be thinking a reseat of the buffer connector.

At least you know which boards work now.

[Fool2cool]

Re: Panasonic TX-P42S11B - 7 Blink Code

Haha should I take that as a compliment?

Yeah its very strange that the line just stops, and you can actually see a physical mark with the panel turned off. The data connector on the C1 board I think it is on the far right where the vertical line is also gets very hot, I think if I understand correctly these have a chip on flex? and the large metal bracket is a heatsink?

I've also re-seated the buffer connector a few times but it doesn't help.

Thank you

[tom66]

Re: Panasonic TX-P42S11B - 7 Blink Code

That is quite likely a panel problem due to misaligned electrode (factory defect)


Page 53.

[Fool2cool]

Re: Panasonic TX-P42S11B - 7 Blink Code

That is quite likely a panel problem due to misaligned electrode (factory defect)


Page 53.

Thank you for the link Tom, is this a problem you've come across before?