Samsung PS43F4500 sparkles, retention, bad picture

[mutts]

Hello
I have been given a 6yr old plasma to fix or dump.
There is an odd solarization type effect at the top of the screen, sparkles and image retention of previous menus, logos or anything that has remained static for more than a few seconds.

Va, vs and vscan are all correct, all voltages on the psu are correct and stable. Tv boots fine and led on mainboard flashes once a second. I can't find any shorts on the ysus buffer board.

Odd thing i have noticed that if i temporarily disconnect one of the E buffers then the working side of the panel displays near normal. same effect for both E buffers.

Also if vs is briefly increased from 208 to 218v the picture greatly improves. Changing vscan from -185 to -175v removes the sparkles.

Is there anyone with experience of plasmas could give some ideas please would be most appreciated.
Many thanks

[Unspun01]

Re: Samsung PS43F4500 sparkles, retention, bad picture

As a plasma panel ages, some pixels get used more than others and over time they will wear out differently.

Individually, a pixel may no longer be as bright, or not as white as it used to be (shifting to more reddish/pinkish)

Your major voltages VA VS Vscan are all within the specs posted on the panel... However, you can greatly improve the image quality on older LG and Samsung panels by very slightly changing these voltages (as you have noticed)

If you change the voltages slightly from the stated specs to improve the image quality, then you should be fine.

Don't do these measurements/adjustments on a cold TV. Let the TV warm up 15 minutes and then perform a few adjustments while watching TV.

Honestly, my preferred method of adjusting an older plasma TV is with the back off, and watching TV commercials with a PVR (so you can pause). Yes commercials. Unlike a movie, where there can be lots of dark scenes, TV commercials have lots of contrast and bright colors, and lots of different facial color tone palettes.

As you are watching TV (a large mirror is very helpful), if any image seems "off" to you, pause that particular scene and CAREFULLY adjust (with a non-conductive screwdriver if possible) to try and improve the image. Then continue watching to ensure you didn't make it worse for other scenes.

After 10-15min you will find a sweet spot in which most of your image issues will have gone away and you will have a very watchable TV.

If you have severe burn in, then no adjustments will make it much better. But for sparklies, or image retention, or odd washouts or color grading (especially on human faces) then be patient and adjust carefully.

Always make note of your original voltage readings, but specifically make a small mark, or note the exact location of the potentiometer adjustment... You do not want to turn too far or you can physically damage the pot, or run outside of normal voltages and burn something out.

I have never ever had to adjust a Panasonic plasma TV in this way as they just seem to have amazing picture quality (unless you have a failed SC board... grrrrrr)

[mutts]

Re: Samsung PS43F4500 sparkles, retention, bad picture

Many thanks unspun for the advice, I did wonder if the panel age and not helping with the problem, what got my repair curiosity going (other than it being a freebie) was that the fault started suddenly one morning shortly after it was turned on which shouts 'failed component'.
Good tip about using commercials, I've always favoured a news channel as it doesn't change much.

[Unspun01]

Re: Samsung PS43F4500 sparkles, retention, bad picture

HaHaha... Funny you mentioned news channel because that's exactly what I do... Plenty of commercials on the news channel, and nice vivid color with lots of facial tones... I forgot to mention the channel with the commercials I usually watch is a news channel... You get to stay current on world events even if not paying attention

I've seen potentiometers that exhibit that behavior you describe. Adjusting the potentiometer back and forth a few times (TV OFF) can break the oxidation that caused the poor connection and then re-adjust with tv on as needed.

I had a TV that once had very weird voltages that would work sometimes and not work at other times... or would sporadically jump from good picture to bad picture... Replacing the bad pot on VA or VS was the fix.

Keep an eye on it.