Panasonic TC-P55GT30 7 Blinking Lights... SC Board OK

[Overhed]

Hi everyone,

I've read over most just about all of the 7-blinking light posts on here and they have been very helpful. Long story short, I isolated the SC-board to be problematic so I replaced that. Now when I perform the SU/SD-board isolation test by jumping the SC50 connector, the TV does not shut off and I see the Green light on the SC-board. It does make a kind of buzzing noise, but it looks to be OK.

With this in mind, I ordered replacement SU and SD boards. After connecting them, I still got the 7 blinking lights. I tried every combo of their SU/SD boards and mine and got the same issue. Even though I tested all of the ribbon connectors for shorts and found none, I still decided to order a new set of SU/SD boards since they're all refurbed nowadays and maybe I got unlucky, however the new SU and SD boards I received today gave the same issue.

So this is where I'm stuck at the moment, it would seem like there is something else wrong with the TV apart from the SU/SD boards. Anyone have any ideas? I performed the SC50 isolation test today and the SC-board is still good.

Thanks in advance. I really love this Panny plasma and I don't want to let it go!

[Overhed]

Re: Panasonic TC-P55GT30 7 Blinking Lights... SC Board OK

Bump

[syaoran123]

Re: Panasonic TC-P55GT30 7 Blinking Lights... SC Board OK

Usually if the SC is making a loud noise, q661 is faulty and a column of igbts along the left hand side.

Check the SU Board by seeing if there's a short across capacitor c640. That means one of the buffer chips are shorted.

[Overhed]

Re: Panasonic TC-P55GT30 7 Blinking Lights... SC Board OK

Usually if the SC is making a loud noise, q661 is faulty and a column of igbts along the left hand side.

Check the SU Board by seeing if there's a short across capacitor c640. That means one of the buffer chips are shorted.

Hi Syaoran,

So sure enough C640 is shorted on my original SU board, and the Cap is completely missing on the replacement board I ordered!

I guess I'll look to see if there's any of the same cap on my original board that I can solder off and put on my "new" board?

[budwich]

Re: Panasonic TC-P55GT30 7 Blinking Lights... SC Board OK

is your "c640 is shorted" statement made after an out of board test of the CAP. The previous poster's point was that the buffer itself is shorted not necessarily the cap. The cap may not be necessary depending on design and versions of boards. Your replacement board might be older while the existing one maybe newer and has some "improved design".

[Overhed]

Re: Panasonic TC-P55GT30 7 Blinking Lights... SC Board OK

is your "c640 is shorted" statement made after an out of board test of the CAP. The previous poster's point was that the buffer itself is shorted not necessarily the cap. The cap may not be necessary depending on design and versions of boards. Your replacement board might be older while the existing one maybe newer and has some "improved design".

No, I tested the cap on-board. I guess I see your point, though -- my original board is a 5340AK and the refurbed board I purchased is a 5340, so most likely different revisions.

EDIT:
I just confirmed the above -- saw a picture of the 5340 revision of the board online and it does not have a cap at C640.

Second EDIT:
After checking the new SU board's ribbon connectors, it looks like one of them does in fact have a short (as does one of the connectors on my original SU board).
Any recommendations for a reliable site where I can get one of these boards from? I ordered these from TVPartsToday.com

[tvtimmy]

Re: Panasonic TC-P55GT30 7 Blinking Lights... SC Board OK

Send it back and tell them to send another. They have 11 in stock.

[Overhed]

Re: Panasonic TC-P55GT30 7 Blinking Lights... SC Board OK

Send it back and tell them to send another. They have 11 in stock.

Just called them and they will be sending me a return label so we can swap boards.

I'll keep you guys posted. Thanks for your help thus far.

[syaoran123]

Re: Panasonic TC-P55GT30 7 Blinking Lights... SC Board OK

Yup my point was... The c640 test is a good indicator that one or more of your buffer chips are shorted. It's not a defect with the capacitor, and sometimes it's normal to have no capacitor in there depending on version. The part that needs replacement is the buffer chip which requires the correct tools and painstaking work.

You could of course test the ribbon connectors individually which you already did.

Glad you have diagnosed the problem and they are happy to accept returns

[tvtimmy]

Re: Panasonic TC-P55GT30 7 Blinking Lights... SC Board OK

To test them, put a probe on the red "variable floating ground" circled in red, and rake across the ribbon connectors(also wth red line). A beep in continuity mode means a short.

[Overhed]

Re: Panasonic TC-P55GT30 7 Blinking Lights... SC Board OK

Hi all,

Just wanted to drop-in to let everyone know that after putting in the replacement SU board (and re-seating the SD/SU-board ribbons like half a dozen times), my TV has resurrected and looks as good as ever!

Thanks so much for everyone's help and thank you bad-caps, there's no way I would have been able to get it fixed without all the resources I found on this community.

[syaoran123]

Re: Panasonic TC-P55GT30 7 Blinking Lights... SC Board OK

Thnaks for the feedback

[tvtimmy]

Re: Panasonic TC-P55GT30 7 Blinking Lights... SC Board OK

Good job. For some reason my picture didn't show up. Here is the floating variable ground circled in red. Put a probe on it and rake the other one across the ribbon connector ( with red line).

[Jo43jo]

Re: Panasonic TC-P55GT30 7 Blinking Lights... SC Board OK

I would like to ask a question. My 55GT30
failed with the 7 blinks of death. My checking
confirms the SC board is shorted, I think I can
handle that. Also Q661 is not shorted. The SU
and SD show No short placing the Red lead on
the proper ground and scanning the flex lead
connectors. But if I place the Red lead on ground
and scan the connectors all show .785 ohms!
Do I have a problem? Which is the proper way?
Thanks Jo

[Jo43jo]

Re: Panasonic TC-P55GT30 7 Blinking Lights... SC Board OK

CORRECTION. my proof reading is poor.
With Red lead on ground and scanning with Black,
No shorts! But scanning with Black on ground and scanning
with Red all are shorted!

[tvtimmy]

Re: Panasonic TC-P55GT30 7 Blinking Lights... SC Board OK

Does your meter beep when you touch the two probes together?

[Jo43jo]

Re: Panasonic TC-P55GT30 7 Blinking Lights... SC Board OK

Original post no, but showes zero ohms. I have now
Will measure with a different Fluke with higher pitch.
If I place the black lead on ground and scan connectors
With Red lead No beeping. If I reverse the leads I get some
beeps.

[Jo43jo]

Re: Panasonic TC-P55GT30 7 Blinking Lights... SC Board OK

Also, there are no shorts between pins 2 and 6
of SU41, SD42, or SD46.