Panny TC-P50G25 bad SC board -- what else to check?

[AnthonyC]

Thanks to the troubleshooting guide on this forum and many threads, I diagnosed a bad SC board on my Panasonic plasma TV. Dead short on the Vsus line to the SC board. Other boards connecting to power showed good resistance.

No obvious damage to the board (scorch marks, cracked components, bulging caps). I checked the screws, since that was mentioned as a problem and they all seemed tight with no discoloration or other indications of arcing.

Original symptom was the TV worked in the morning. In the afternoon, I heard the relays click, then click again, and no picture. It was blinking a four blink code.

First -- anything else to check as to why the SC board failed short? I'd hate to repair/replace and have this happen again.
Second -- self repair or send it out? I'm pretty good at soldering macro-size components but have no experience with surface mount. So I'm leaning towards paying for a repair.

Is PTS Electronics still the go-to for this? I saw them recommended a lot in other threads.

Thanks all!
Anthony

[Moreno83]

Re: Panny TC-P50G25 bad SC board -- what else to check?

What board do you got?

Usually the FETS get shorted. Check the components marked with "Q". ( For example Q661 ).

Meter in diode/continuity mode and propes on outer legs. ( black on left leg , red on right and reverse ). Beep is bad.

Same with the parts labeled with "D". They are diodes but you need to measure them differently. Black prope on middle leg and red on left/right leg.

[tw2005]

Re: Panny TC-P50G25 bad SC board -- what else to check?

Thanks to the troubleshooting guide on this forum and many threads, I diagnosed a bad SC board on my Panasonic plasma TV. Dead short on the Vsus line to the SC board. Other boards connecting to power showed good resistance.

No obvious damage to the board (scorch marks, cracked components, bulging caps). I checked the screws, since that was mentioned as a problem and they all seemed tight with no discoloration or other indications of arcing.

Original symptom was the TV worked in the morning. In the afternoon, I heard the relays click, then click again, and no picture. It was blinking a four blink code.

First -- anything else to check as to why the SC board failed short? I'd hate to repair/replace and have this happen again.
Second -- self repair or send it out? I'm pretty good at soldering macro-size components but have no experience with surface mount. So I'm leaning towards paying for a repair.

Is PTS Electronics still the go-to for this? I saw them recommended a lot in other threads.

Thanks all!
Anthony

You could try the repair, most large kits probably cover the known bad bits, safest way is get it done if you're happy with the cost.

Check the sd/su are still ok and not shorted. Then give the ol girl a pat and thank her for giving you 7 solid years .

Why they fail, they do. Mine failed at 18 months and 2500 hrs. I now have 18000 hrs still waiting for another failure. One thing I noticed with mine (Rev AF) was some earth pads were missing topside compared to other boards I'd seen. WHO knows.

generally there are no loose bolt issues it's the 2011 models that changed the bolt type.

I just picked up one with only 4500hrs, blown sc. Looks like it's sat under the house for a few years. popped a spare in and she's all beautiful again.

Considering the issues with LED backlights eg LG and TVs with lenses falling off and burning out in 2 years. I think the panasonic plasma has better durability and repairability. Bit hard on the Kilowatts that's all.

[AnthonyC]

Re: Panny TC-P50G25 bad SC board -- what else to check?

I have a 5081AF SC board.

I'll take a look at the Q's and diodes.

How do I check the sd/su for shorts? Specifically, which connectors and pins should I check?

Thanks guys.

[heavymachines]

Re: Panny TC-P50G25 bad SC board -- what else to check?

https://www.youtube.com/watch?v=-JVLWpcIxJQ watch this basically same procedure to testing any buffer boards on any plasma.

[AnthonyC]

Re: Panny TC-P50G25 bad SC board -- what else to check?

Question: which way is bad for the diodes to read? I was measuring middle out (black middle, then red on either of the legs). It seemed like they all beeped on both legs when I did that.

The FETs were another matter:

Q402 L/R short
Q403 L/R short
Q421 L/R short
Q422 L/R short
Q441 Okay
Q442 Okay
Q452 L/R short
Q621 Okay
Q622 L/R short
Q660 Good


Checking buffer boards now.

Thanks.

[AnthonyC]

Re: Panny TC-P50G25 bad SC board -- what else to check?

Do I have to take the ribbons off to check the SD/SU boards? Seems like I could do more harm than good if I didn't have to.

[heavymachines]

Re: Panny TC-P50G25 bad SC board -- what else to check?

Do I have to take the ribbons off to check the SD/SU boards? Seems like I could do more harm than good if I didn't have to.

best to test them by themselves so no false readings youtube how to do this safely and effectively its not hard to do.

[AnthonyC]

Re: Panny TC-P50G25 bad SC board -- what else to check?

I also saw there is another row of pins under the ribbons. Just finished checking them and very carefully putting the ribbons back in.

No shorts to ground on any of the ribbons, so I'm hoping it's good there.

[heavymachines]

Re: Panny TC-P50G25 bad SC board -- what else to check?

I also saw there is another row of pins under the ribbons. Just finished checking them and very carefully putting the ribbons back in.

No shorts to ground on any of the ribbons, so I'm hoping it's good there.

If done right should be ...

[heavymachines]

Re: Panny TC-P50G25 bad SC board -- what else to check?

Question: which way is bad for the diodes to read? I was measuring middle out (black middle, then red on either of the legs). It seemed like they all beeped on both legs when I did that.

The FETs were another matter:

Q402 L/R short
Q403 L/R short
Q421 L/R short
Q422 L/R short
Q441 Okay
Q442 Okay
Q452 L/R short
Q621 Okay
Q622 L/R short
Q660 Good


Checking buffer boards now.

Thanks.

Depends on the of diode type. plenty of youtube vids , 3 legged diodes etc, zener, etc

[AnthonyC]

Re: Panny TC-P50G25 bad SC board -- what else to check?

I was more interested if these inparticular were supposed to be middle-out or outside-in for direction. It was late last night and I did not get a good look at the diode case markings. I'll give it a more thorough try tonight.

Where can I source the FETs? I tried the part numbers in Digikey and it came up blank. SJ has 5 packs of some parts, but were out of stock. Just wondering where else to look.

[tw2005]

Re: Panny TC-P50G25 bad SC board -- what else to check?

I was more interested if these inparticular were supposed to be middle-out or outside-in for direction. It was late last night and I did not get a good look at the diode case markings. I'll give it a more thorough try tonight.

Where can I source the FETs? I tried the part numbers in Digikey and it came up blank. SJ has 5 packs of some parts, but were out of stock. Just wondering where else to look.

You better read my TNPA5081 thread, There's some surface work and ICs needed too generally. Keep in mind if this goes wrong you won't be able to send that board to anyone.

[AnthonyC]

Re: Panny TC-P50G25 bad SC board -- what else to check?

I'm about 10% into that thread now. I'll keep at it, though. Thanks for the help.

Still leaning towards PTS. Just want one more day to take a look at things before committing.

[heavymachines]

Re: Panny TC-P50G25 bad SC board -- what else to check?

Where can I source the FETs? I tried the part numbers in Digikey and it came up blank. SJ has 5 packs of some parts, but were out of stock. Just wondering where else to look.

List the numbers and someone will list a compatible one that will work.

[AnthonyC]

Re: Panny TC-P50G25 bad SC board -- what else to check?

I caved and sent it to PTS. They got it Monday and I got it back today. Plugged her in and it fired up nice. I looked at the menu and it appears all lines look fine. I'll plug it into the cable box and see full video to verify.

Thanks for the help. Even though I didn't do the soldering, it was nice to know I had the bad board isolated and what was wrong with it.

[tw2005]

Re: Panny TC-P50G25 bad SC board -- what else to check?

I caved and sent it to PTS. They got it Monday and I got it back today. Plugged her in and it fired up nice. I looked at the menu and it appears all lines look fine. I'll plug it into the cable box and see full video to verify.

Thanks for the help. Even though I didn't do the soldering, it was nice to know I had the bad board isolated and what was wrong with it.

not a bad idea, stress free. look at that, identified the bad bit sent it in, rebuilt, installed watching telly