Panasonic TC-P46ST30 Fixed SC Board But Still Have a Display Issue

[aaronwt6]

Re: Panasonic TC-P46ST30 Fixed SC Board But Still Have a Display Issue

Ok. I'll begin wherever you suggest this evening on testing. Sure wish I had an extra set of parts to throw at it right about now.

[tw2005]

Re: Panasonic TC-P46ST30 Fixed SC Board But Still Have a Display Issue

Ok. I'll begin wherever you suggest this evening on testing. Sure wish I had an extra set of parts to throw at it right about now.

Obvious question but those tabs heated up enough to have soldered correctly back onto the board?

[aaronwt6]

Re: Panasonic TC-P46ST30 Fixed SC Board But Still Have a Display Issue

I believe so. I could reheat them. One of the diodes seemed like it didn't want the solder to flow under it as well but it was certainly stuck. I had my iron turned up all the way so it was quite hot.

[tw2005]

Re: Panasonic TC-P46ST30 Fixed SC Board But Still Have a Display Issue

I believe so. I could reheat them. One of the diodes seemed like it didn't want the solder to flow under it as well but it was certainly stuck. I had my iron turned up all the way so it was quite hot.

yeah , well it's a bugger. Was exact same SC I did for 50" , only the 4 IGBTs were bad, I left the rest,

[aaronwt6]

Re: Panasonic TC-P46ST30 Fixed SC Board But Still Have a Display Issue

I'll check my voltages this evening on everything and re-heat all those just in case. If you had to just take a shot in the dark would your guess be that the SC still has additional issues? I really feel like the possibility of the SS being bad too at the same time is slim. I'm tempted to just order another SC so I can have a shot at this thing running by next Tuesday then troubleshooting the board this evening.

Not sure if you'll be around in 11-12 hours but that's when I'd have time. I know you hang out here frequently. Again, I really appreciate your time and hope I can get somewhere with it later today.

Thanks again,

Aaron

[aaronwt6]

Re: Panasonic TC-P46ST30 Fixed SC Board But Still Have a Display Issue

And yes, I think D401 and D421 were ok but I changed them out since I had the parts and it was recommended.

[tw2005]

Re: Panasonic TC-P46ST30 Fixed SC Board But Still Have a Display Issue

I'll check my voltages this evening on everything and re-heat all those just in case. If you had to just take a shot in the dark would your guess be that the SC still has additional issues? I really feel like the possibility of the SS being bad too at the same time is slim. I'm tempted to just order another SC so I can have a shot at this thing running by next Tuesday then troubleshooting the board this evening.

Not sure if you'll be around in 11-12 hours but that's when I'd have time. I know you hang out here frequently. Again, I really appreciate your time and hope I can get somewhere with it later today.

Thanks again,

Aaron

probably an area for a CRO and that's more tom's speciality. If a voltage was out enough it would trip. Try the test patterns and see if any seemed 100% normal..

Did this have loose screws and burn marks?
All the earth points were cleaned up , new screws and maybe some reflow of the earth points underside of the SC?

[aaronwt6]

Re: Panasonic TC-P46ST30 Fixed SC Board But Still Have a Display Issue

Nearly every screw on all the boards needed a 1/4 turn to snug them up. Same as my 55" version of the same TV that I have in my living room. I repaired that SC board a little over a year ago, tightened all the screws, and have been watching it since. Both it and this 46" were described as briefly having the buzzing sound before they quit.

I did not do anything as far as cleaning the ground points but I did add lock washers to the screws on the SC board and buffers.

Oh, and no burn marks anywhere that I could see.

[tw2005]

Re: Panasonic TC-P46ST30 Fixed SC Board But Still Have a Display Issue

Nearly every screw on all the boards needed a 1/4 turn to snug them up. Same as my 55" version of the same TV that I have in my living room. I repaired that SC board a little over a year ago, tightened all the screws, and have been watching it since. Both it and this 46" were described as briefly having the buzzing sound before they quit.

I did not do anything as far as cleaning the ground points but I did add lock washers to the screws on the SC board and buffers.

Oh, and no burn marks anywhere that I could see.

Yeah , well I cleaned mine up and added solder. Some were pretty dodgy with no solder left and black. I put all the pics in my thread.

[aaronwt6]

Re: Panasonic TC-P46ST30 Fixed SC Board But Still Have a Display Issue

I'll take a look at that and do as you suggest this evening as well as reheat the tabs on everything I installed. Will post back with updates.

[aaronwt6]

Re: Panasonic TC-P46ST30 Fixed SC Board But Still Have a Display Issue

I took the board back out and checked all the ground connections. A few were sketchy but I don't think they were affecting anything. Cleaned those up and added solder to them. I checked Vs and it's 220V. This seems high to me but I haven't worked on a plasma this new and there's no label on the panel. Tom, if you get on here please let me know what if any other voltages I should check. I may get another board on the way for backup just in case. Assuming that the problem actually still lies in the SC board.

[tom66]

Re: Panasonic TC-P46ST30 Fixed SC Board But Still Have a Display Issue

220V is really quite high for a panel like this. (Panel response is quite nonlinear so going up by just 10V can have a huge effect.) And I have heard that high Vsus can cause blue and green sparkles. Try dropping Vsus to about 205V ~ 210V.

The best way to adjust Vsus is full white: Put a full white pattern up, and adjust it down until you see one of a few things:
- Dead/misfiring/intermittent pixels
- Pink banding on the screen (may flicker slightly)
- Unevenness to the white level, such as a light grey band

At that point, add 2V and call that the final voltage.

[aaronwt6]

Re: Panasonic TC-P46ST30 Fixed SC Board But Still Have a Display Issue

Let me get you a few pics real quick. I'm unsure which pot is Vs. There are at least two and I don't think they are labeled that way.

[tom66]

Re: Panasonic TC-P46ST30 Fixed SC Board But Still Have a Display Issue

Panasonic call it Vsus (Voltage Sustain)

[aaronwt6]

Re: Panasonic TC-P46ST30 Fixed SC Board But Still Have a Display Issue

I believe these should be adequate. I see two. Both on the right side of the board.

[aaronwt6]

Re: Panasonic TC-P46ST30 Fixed SC Board But Still Have a Display Issue

Yeah. I knew that about Vsus but I'm used to the LGs with the Pot labeled.

[aaronwt6]

Re: Panasonic TC-P46ST30 Fixed SC Board But Still Have a Display Issue

I think it's got to be VR251 near the bop of the board by the connector to the SS board bunt I want to be sure.

[aaronwt6]

Re: Panasonic TC-P46ST30 Fixed SC Board But Still Have a Display Issue

You're a genius Tom as usual. I dropped the voltage down to just 216 and it cleared up. At 211 it started looking rough again so I settled at 213 and it is perfect. I'll take some pictures after I get my son to bed in a bit. I would have never thought a few volts could make that much difference. Not to mention they were factory set and the TV is only a few years old with less than 2 of actual use on it.

[aaronwt6]

Re: Panasonic TC-P46ST30 Fixed SC Board But Still Have a Display Issue

Thanks again for the advice / guidance.

[tw2005]

Re: Panasonic TC-P46ST30 Fixed SC Board But Still Have a Display Issue

Interesting it needed adjustment if the seal was unbroken. what is Vsus set to in the service menu? Mine is set to low. Mind you I changed mine to high and barely any difference.

Anyway glad you got it sorted