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

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.

[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

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

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

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

[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

[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 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

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

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.

[aaronwt6]

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

And yeah, first thing I did was double check all my connections. I sure was bummed when I saw the problem. I fired it up, saw the menu, grabbed a celebratory beer to sit back and watch it for a while, and then saw all the sparkles.

[tw2005]

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

yeah, picture 3 shows more of an issue. Test patterns / full white could be interesting. Does remind me of the SS board I accidentally removed 50% of the drive signal when I tagged a SMD 100 ohm resistor and removed it by accident.

Maybe like Tom is suggesting, something extra damaged like driver ic

[aaronwt6]

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

The bottom is worse but look at my 3rd picture as well as the last. It's definitely affecting the whole screen. Tom, I did not check the driver IC. What is it's location and what should I be checking on it?

[tw2005]

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

Also, not sure if this is a factor but I was a bit concerned with how much I had to heat the diodes and fets to remove them. I cut a hole in a piece of foil to shield the remainder of the board while I heated each one but man did I ever have to apply some heat to get them loose. I'd said a good 30-45 seconds on each one with my Weller hot air station on it's highest setting. Was concerned about heating other parts on the board.

I just did my first of this series, had same issue, Doubt it's that. Mine went smooth and I reckon may have put more heat. felt like forever.

not real sure which way you should go if everything is hooked up right and tight. I'll have another look but it really seemed just bottom 50% affected

[tom66]

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

Also, not sure if this is a factor but I was a bit concerned with how much I had to heat the diodes and fets to remove them. I cut a hole in a piece of foil to shield the remainder of the board while I heated each one but man did I ever have to apply some heat to get them loose. I'd said a good 30-45 seconds on each one with my Weller hot air station on it's highest setting. Was concerned about heating other parts on the board.

It took me a minute to remove the IGBTs using my soldering iron. I think it's normal, the board is a heatsink for the devices, and consequently can suck away a lot of the heat...

[tom66]

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

Personally I doubt SU or SD would cause this issue.
Did you check the ERC IGBT driver IC? (near the inductor)

[aaronwt6]

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

My instinct is telling me that there is something else wrong with the SC based on what the previous owner told me about it looking fine up until the point of failure.

[aaronwt6]

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

Also, not sure if this is a factor but I was a bit concerned with how much I had to heat the diodes and fets to remove them. I cut a hole in a piece of foil to shield the remainder of the board while I heated each one but man did I ever have to apply some heat to get them loose. I'd said a good 30-45 seconds on each one with my Weller hot air station on it's highest setting. Was concerned about heating other parts on the board.

[aaronwt6]

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

I believe the resistor you are referencing is just lifted up a tad on one side. The iron I have is a bit large for working on those given their size. All 4 were new and the same. I'm not showing any shorts on either buffer board but that's not to say there isn't something wrong. The problems seems worse on the lower half of the screen, but it's certainly showing up on the entire thing. I was looking for a starting point on what to check tonight. Hate the thought of buying the entire set of 3 boards but I'd do that if I thought it was going to solve the problem.

[tw2005]

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

SO looks like all the resistors replaced, all 7.5ohm I guess? R422, just looks a bit different, right side in photo.

Did you check the SD SU boards ? second last photo seems to indicate it is SD board that 's having an issue. Could be the SD or SC