Diagnosis help for 7 blinks on Panasonic TC-P46G10

[manicscholar]

Hello all,

My first thread so I hope I cover the problem well enough.

It's a Panasonic TC-P46G10 which has the 7 blink problem.

I suspect it is the A-board but I hope to get some opinions on this diagnosis. Troubleshooting steps are as follows.

I have read a few threads on here and performed the SU/SD isolation test by disconnecting everything between SC and SU/SD and shorting SC50. The blink code changes to 6 blinks.

I have then followed instructions from the Panasonic 12th gen plasma tech guide for SC board isolation, p59 from here: https://cdn.badcaps-static.com/pdfs/...a446da4b30.pdf
(disconnect SC2, SC20 and SS33)

On performing SC board isolation test, the blink code remains at 7. Results are the same if SS board power is also disconnected.

Based on these two tests my conclusion is an A board failure. Any feedback on this would be appreciated before I order a $70 replacement.

Cheers

[foxyUK]

Re: Diagnosis help for 7 blinks on Panasonic TC-P46G10

Hello all,

My first thread so I hope I cover the problem well enough.

It's a Panasonic TC-P46G10 which has the 7 blink problem.

I suspect it is the A-board but I hope to get some opinions on this diagnosis. Troubleshooting steps are as follows.

I have read a few threads on here and performed the SU/SD isolation test by disconnecting everything between SC and SU/SD and shorting SC50. The blink code changes to 6 blinks.

I have then followed instructions from the Panasonic 12th gen plasma tech guide for SC board isolation, p59 from here: https://cdn.badcaps-static.com/pdfs/...a446da4b30.pdf
(disconnect SC2, SC20 and SS33)

On performing SC board isolation test, the blink code remains at 7. Results are the same if SS board power is also disconnected.

Based on these two tests my conclusion is an A board failure. Any feedback on this would be appreciated before I order a $70 replacement.

Cheers

I'm struggling to understand the diagnostic on page 59, as it just says the screen is black without referring to the error codes again. On later models the 7-blink is almost always down to the SC board, not the A board. Could be different on these models of course, but suggest checking the power components on the SC for shorts.
Have you checked that SC2 is not shorted and has the correct Vsus voltage on it?

[manicscholar]

Re: Diagnosis help for 7 blinks on Panasonic TC-P46G10

Thanks a lot for the response.

Yeah, the manual is not clear. The way I understand (from reading around) the way the troubleshooting method for Panasonic is if you isolate the problem (de-energize it) the screen should turn on as blank, with no LED codes.

The fact that the SS and SC board are completely isolated but the TV still returns a 7 blink code seems that the module responsible for reporting the fault is to blame, which I believe is the A board - that's how I've arrived at this conclusion. Does that make sense?

What voltage should be on Vsus? I can measure that now. Is that measured to the chassis earth or between two pins?

[tom66]

Re: Diagnosis help for 7 blinks on Panasonic TC-P46G10

7 blinks, especially on a G10, is almost always due to the SC or SS.
You'll still get 7 blinks if you isolate the board because the SC did not send the "OK" signal back to the A board and it's assumed to be faulty.
You can try and check the TP_SOS7 signal test point for voltage near the ribbon cable that goes to the A board. I believe it should be low during normal operation (~0V) and high during a fault (~3V)

[manicscholar]

Re: Diagnosis help for 7 blinks on Panasonic TC-P46G10

Thanks Tom. The manual I pointed out seems to imply otherwise that isolation should result in a blank screen/no blinks. If the A board requires an "OK" signal then I would think TP_SOS7 (or its OK counterpart) would need to be a high signal.

Tested TP_SOS7, it returns 0V.

Any further thoughts?

[tom66]

Re: Diagnosis help for 7 blinks on Panasonic TC-P46G10

The fault code is a high signal, according to the schematic. But it may go high then low again. Try checking the voltage as the set turns on, ideally with a scope but if not a multimeter may be sufficient.

[manicscholar]

Re: Diagnosis help for 7 blinks on Panasonic TC-P46G10

Unfortunately I only have a multimeter here. There does to seem to be a very transient high signal (<1s) for when switched on which resolves to 0V in steady-state.

You mentioned earlier that the A board expects to receive an "OK" signal from the SC board, is there a test point from this? Or is constant 0V from the TP_SOS7 the "OK" it is looking for?

[tom66]

Re: Diagnosis help for 7 blinks on Panasonic TC-P46G10

The A board wants to see a low signal from the SC board. 0V would be that signal but if it's high for several seconds, I would suggest that might be indicative of a fault.

[manicscholar]

Re: Diagnosis help for 7 blinks on Panasonic TC-P46G10

Thanks.

I might just give up on this. If the SC board is disconnected, isolated from the rest of the TV, then the A board would never receive a high voltage fault signal from the SC. Which is why I don't see how it could return the 7 blink error code unless something is wrong in the fault detection system on the A board.

[tom66]

Re: Diagnosis help for 7 blinks on Panasonic TC-P46G10

Thanks.

I might just give up on this. If the SC board is disconnected, isolated from the rest of the TV, then the A board would never receive a high voltage fault signal from the SC. Which is why I don't see how it could return the 7 blink error code unless something is wrong in the fault detection system on the A board.

The A board has a pull up on it, I think, so a disconnected SC looks like a faulty one.
The advice in the Panasonic service manuals is not always correct.

[manicscholar]

Re: Diagnosis help for 7 blinks on Panasonic TC-P46G10

I see - thanks for your time and advice. Replacement SC board seems rare and expensive. Lacking the time to go through it component by component. A shame!

[foxyUK]

Re: Diagnosis help for 7 blinks on Panasonic TC-P46G10

It's usually pretty simple to diagnose an SC board as the IGBTs fail short circuit so can be checked in seconds with your multimeter.