SU/SD board troubleshooting help requested for 7 blinks on Panasonic TC-P50GT30

[willdeed]

Hello badcappers,

Another annoyed Panasonic owner (TC-P50GT30) with 7 blinks. Want to say first of all, thanks for all the posts so far. This forum has been the most help by far in figuring out what's going on with this issue.

Here's a summary of my situation:

- Heard a loud pop when watching TV and now only getting 7 blinks.
- Disconnecting SC2 and SC20 gives 8 blinks
- Disconnecting SS11 as well gives 6 blinks
- Continuity test across the two leads of SC2 indicates short (beeps)
- Continuity test across the leads on SS11 does not beep, but I'm not exactly sure if this is a helpful test..
- From what I've read, I assume at least the SC board (and maybe SU/SD boards... maybe even SS?) is/are bad.
- I noticed the bottom 2 screws holding down the SC board were loose. There are some minor burn marks on both sides of the SC board (pics attached), but no visual problems with any components on SC/SU/SD boards

My questions:

- How do I properly troubleshoot the SU/SD boards? There are test points around the SC connectors labeled TPSUXX and TPSDXX (with the Xs being numbers -- pic attached), but I don't know the other point I should be using on these for doing a continuity test.
- Once I know how to actually use these test points effectively, is this enough troubleshooting to safely say the SU/SD boards are still good and only need to send the SC board for repair?

I've found on ModusLink that it's about $140 for repairing the SC board and about $100 more to repair the SU/SD/SS boards as well. I don't mind paying the extra, but I'm actually concerned with disconnecting/reconnecting the ribbons on the buffer boards.

Also, I just like brushing off the cobwebs on my MM and getting a practical refresher on electronics

Any help is appreciated.

[willdeed]

Re: SU/SD board troubleshooting help requested for 7 blinks on Panasonic TC-P50GT30

any help?

[tw2005]

Re: SU/SD board troubleshooting help requested for 7 blinks on Panasonic TC-P50GT30

any help?

Patience.

SC would be prime suspect with loose screws and possibly poor earthing.

First step for a 7 blink would be to perform the SD/SU isolation test.

What you do is have everything hooked up normally, make sure the SC is mounted correctly and screws firm for good earth.

Disconnect the 3 connections from the SC to the SD/SU, remove the 4 mounting/earth screws for the SD/SU (2 each)

On the SC there will be a small 2 pin white connector labelled SC50. Those 2 pins need to be shorted together.

Then turn the TV on. If the Sc is good the TV will turn on and stay on no picture. Do this long enough to confirm then turn off.

If it passes then the SD/SU are suspect, if it fails the the SC is shot and SD/Su still need to be tested for shorts.

Pretty sure I've read a few post of buffers going but this first step short get you in the ball park at least.

[willdeed]

Re: SU/SD board troubleshooting help requested for 7 blinks on Panasonic TC-P50GT30

Patience.

SC would be prime suspect with loose screws and possibly poor earthing.

First step for a 7 blink would be to perform the SD/SU isolation test.

What you do is have everything hooked up normally, make sure the SC is mounted correctly and screws firm for good earth.

Disconnect the 3 connections from the SC to the SD/SU, remove the 4 mounting/earth screws for the SD/SU (2 each)

On the SC there will be a small 2 pin white connector labelled SC50. Those 2 pins need to be shorted together.

Then turn the TV on. If the Sc is good the TV will turn on and stay on no picture. Do this long enough to confirm then turn off.

If it passes then the SD/SU are suspect, if it fails the the SC is shot and SD/Su still need to be tested for shorts.

Pretty sure I've read a few post of buffers going but this first step short get you in the ball park at least.

Thanks for the reply, tw2005! You and tom66 have helped a lot of people on these forums, so much appreciated.

I isolated the SC board and still came up with 7 blinks, so sounds like it is definitely shot.

Found your post on testing the buffer boards here so going to give that a shot now.

Thanks again!

[willdeed]

Re: SU/SD board troubleshooting help requested for 7 blinks on Panasonic TC-P50GT30

hmm... think I'm doing it wrong.

If I understand those buffer test instructions correctly, I should be able to put one lead of the MM on TPSU18 and one on TPSU15 and get an ohms reading. When I do that, my MM doesn't budge from OL.

I also tried using a screw or just the case instead of TPSU18 for ground and tried all of the test points mentioned (TPSU15-17, TPSD26, TPSD28, TPSD29).

Using a cat III MM (Craftsman 82314).

What am I missing?

[tw2005]

Re: SU/SD board troubleshooting help requested for 7 blinks on Panasonic TC-P50GT30

my brain has not switched on but what range is the meter set to?

As a quick check, set continuity and try earth and sliding the other probe slowly along the output pins of each ribbon connector of the buffers.

should not be shorted

[tw2005]

Re: SU/SD board troubleshooting help requested for 7 blinks on Panasonic TC-P50GT30

I don't know off the top of my head if the SD/SU pinouts are the same for a g20 and gt30

See if this helps

[willdeed]

Re: SU/SD board troubleshooting help requested for 7 blinks on Panasonic TC-P50GT30

It's set to auto. I figured the ohms may be different, but assumed testing those points would at least give me something.

I did a continuity test along the outside pins of each of the panel ribbon connectors and didn't get any beeps.

Is this the same as testing the connectors to the SC board (SU41/SD42) ?

Having done that, now I'm leaning toward just sending int he SC board for repair and not worrying about the buffer boards until I know the SC board is good. I've been considering sending in the buffer boards at the same time just for the insurance of having them checked out, but, like I said, I'm concerned about disconnecting those panel ribbons. They seem to be pretty tightly connected and there isn't much wiggle room there.

Does repairing the SC board sound like a reasonable next step, or are there other tests that can be done on the buffer boards?

[tw2005]

Re: SU/SD board troubleshooting help requested for 7 blinks on Panasonic TC-P50GT30

It's set to auto. I figured the ohms may be different, but assumed testing those points would at least give me something.

I did a continuity test along the outside pins of each of the panel ribbon connectors and didn't get any beeps.

Is this the same as testing the connectors to the SC board (SU41/SD42) ?

Having done that, now I'm leaning toward just sending int he SC board for repair and not worrying about the buffer boards until I know the SC board is good. I've been considering sending in the buffer boards at the same time just for the insurance of having them checked out, but, like I said, I'm concerned about disconnecting those panel ribbons. They seem to be pretty tightly connected and there isn't much wiggle room there.

Does repairing the SC board sound like a reasonable next step, or are there other tests that can be done on the buffer boards?

Yes, those ribbons are released by lift the catch to release them and then come out pretty easy.

No shorts on the outputs is good, probably not exactly the same as the other tests but the 5v line into those is also part f the check from what I've seen if the 5v is short the buffer outputs will be also.

If the SC failed the SC50 bypass it's faulty.

[instarep]

Re: SU/SD board troubleshooting help requested for 7 blinks on Panasonic TC-P50GT30

Hi , same TV same problem. Done the test to isolate the buffer boards and no more blinking but a loud buzing noise. Any idea where would this come from?

[ljintexas]

Re: SU/SD board troubleshooting help requested for 7 blinks on Panasonic TC-P50GT30

Had the 8 blinks on tcp50vt20 recently..both sd and su were shorted which killed the SC. got lucky and scored an SC board for less than $100. su and sd were cheap from Tristate Module. Sent SC to Moduslink for repair..should be here tuesday is in transit. If it is the same board I will sell it to you for $125 plus shipping whatever actual shipping is. Loose screws on boards were found inside my set as well but no arc marks. previous owner was trying to be tv repairman..lol!There is a procedure for checking the su and sd..tw2005 was a huge help in getting mine diagnosed.

[tw2005]

Re: SU/SD board troubleshooting help requested for 7 blinks on Panasonic TC-P50GT30

Hi , same TV same problem. Done the test to isolate the buffer boards and no more blinking but a loud buzing noise. Any idea where would this come from?

check sc board for loose screws, a loose sc board can resonate and generate a loud buzz

was the green led lit on the sc bright when the set powered on.

[Muccelli]

Re: SU/SD board troubleshooting help requested for 7 blinks on Panasonic TC-P50GT30

I don't know off the top of my head if the SD/SU pinouts are the same for a g20 and gt30

See if this helps

Does anybody have the same for TX-P50GT30E?
Mine is giving the 7 blinks and I am failing the troubleshooting at slide 70 as I (the tv set , actually) have 3 C boards ... All the rest is almost Identical and it looks like I do have an issue with the SD board...at least. But it would be nice to run those additional test to be more sure of what I am going to change

[Muccelli]

Re: SU/SD board troubleshooting help requested for 7 blinks on Panasonic TC-P50GT30

As I have not found any more specific reference, I followed the guidelines for isolating the SU/SD boards. The tv stays then on (black screen , of course, a bit loud-but maybe that is normal?) without red led blinking... Can I safely assume I only need to replace Su/Sd boards and that the SC is instead alive and

[tw2005]

Re: SU/SD board troubleshooting help requested for 7 blinks on Panasonic TC-P50GT30

As I have not found any more specific reference, I followed the guidelines for isolating the SU/SD boards. The tv stays then on (black screen , of course, a bit loud-but maybe that is normal?) without red led blinking... Can I safely assume I only need to replace Su/Sd boards and that the SC is instead alive and

Sounds like it. You could replace the pair or do more tests. Simplest way to check is place a meter in continuity or diode check. Have one probe on the metal ground plate on the sd or su and then carefully slide the other along the face of the output pins at the panel ribbon connectors.

Anything shorted there and that board is bad.

I find these are hard to get and expensive so i've managed to rebuild a couple of boards. Have not struck it on the high end models but on the base U30 and usuall the SU with the top chip or two shorted.

I would remove the SC and clean up the earth points. You mention loud buzzing, can happen running the SC with no load but also if the board is loose.

these are notorious for the bolts being lose, and arc underside losing earth and blowing up. Tighten them up or find some with spring washers or same length like from earlier models 2010 and before. check all other bolts too , SS can also be in the same postion with these loose.

[Muccelli]

Re: SU/SD board troubleshooting help requested for 7 blinks on Panasonic TC-P50GT30

TW2005, many thanks for your inputs, very valuable!
It looks like I am on a typical scenario as running the short test I find the SD to have no shorts and the SU to fail at tpsu17 with~8ohms and at tpsu15 with ~11ohms ( should be pins 2 and 8 of connector SU41).
For the rest you are again perfectly right, I originally unmounted the SC board and noticed some degradation of solder contacts around screws holes on the bottom side, i am planning to rework these before assembling the tv. I managed to find New pair of SU and SD boards on ebay from Germany for about 50€, so I decided to buy them as the panel has very few hours of operation and to me it just gives stunning performances...plus I will have a working reference to guide me in fixing my broken boards and be ready for next fault. I should mention I tried to contact Panasonic for a troubleshooting guide specific to tx-series, if I'll ever be lucky to ping a kind guy and get it , I'll be glad to share it here... In any case I shall report on the outcome, hopefully in one week, the time of getting the parts and to rework the SC bottom plate

[tw2005]

Re: SU/SD board troubleshooting help requested for 7 blinks on Panasonic TC-P50GT30

TW2005, many thanks for your inputs, very valuable!
It looks like I am on a typical scenario as running the short test I find the SD to have no shorts and the SU to fail at tpsu17 with~8ohms and at tpsu15 with ~11ohms ( should be pins 2 and 8 of connector SU41).
For the rest you are again perfectly right, I originally unmounted the SC board and noticed some degradation of solder contacts around screws holes on the bottom side, i am planning to rework these before assembling the tv. I managed to find New pair of SU and SD boards on ebay from Germany for about 50€, so I decided to buy them as the panel has very few hours of operation and to me it just gives stunning performances...plus I will have a working reference to guide me in fixing my broken boards and be ready for next fault. I should mention I tried to contact Panasonic for a troubleshooting guide specific to tx-series, if I'll ever be lucky to ping a kind guy and get it , I'll be glad to share it here... In any case I shall report on the outcome, hopefully in one week, the time of getting the parts and to rework the SC bottom plate

Should be a winner, yes I have accumulated spares for mine too. Got a bunch of boards from france a while back but having manageed to rechip really helped. Touch and go doing it, very fragile the pads,easily torn away.