Samsung PN51F8500 slow pixel response

[ranergeo]

I picked up a Sammy PN51F8500 yesterday with a "burn in" condition. When I got it home and plugged it in, the startup screen looked like it had random horizontal lines of black that filled slowly. The t.v. seems to work fine otherwise, but depending on the picture, random pixels over the panel will just not be lit, or lite up slowly... like it doesn't have enough juice to do so. If I hold an image, it will eventually fill in all the pixels, so I don't think it's a panel.

I thought it might be a voltage problem, so I checked them all, but they were within .2 VDC (although I did correct that as well). I also updated the firmware to the most current with no noticeable change. I checked the Vs voltages to both the X and Y boards, and it's stable to both.

I've attached pictures of the tv, along with some shots of the screen to give a better idea of what I'm talking about. I've been told that re-seating cables might help, but since I don't believe this set has been tampered with, I'm hesitant to do so.

Any ideas as to why this is happening or what next steps I should take?

p.s. As hard as I tried, it was super difficult to capture the "black pixel" issue before they filled in, so I did the best I could... also, the problem seems to be more pronounced where the burn in at the top of the screen is

[freakaftr8]

Re: Samsung PN51F8500 slow pixel response

Yep. Try raising vs about 5v to 8v to compensate for the burn in. This is a problem because the panel has aged in that area and needs a little more juice to wake up the pixels in the burned areas.

[freakaftr8]

Re: Samsung PN51F8500 slow pixel response

Also you could raise VE up a few volts to compensate. There's probably nothing wrong with the actual boards but the panel has aged dramatically and it needs to have a little extra voltage to compensate for the aging of the panel.

The decal on the back of the panel that lists voltages are strictly for new panel set up but does not show you for compensation values of an aged panel.

What a shame that was the last Samsung plasma manufactured in to my understanding they put all the best of the best into it

[ranergeo]

Re: Samsung PN51F8500 slow pixel response

Thanks! I did raise the Vs voltage, as doing so with the Ve isn't possible with this set. It still seems hit or miss...

For example, if I have it on a static screen (such as Amazon Prime menu page), everything looks great, no lost pixels. Once I get things in motion, things get weird and inconsistent. I watched old cartoons (in 4:3) and didn't see any sign of burn in, and only minimal pixel missing. Turned on Top Gear, and again, depending on the scene, would see/not see the burn in band, along with varying amounts of degraded pixles.

And now I've noticed that the tv only stays on for about 15 minutes at a time. A couple times it turned off and back on, and others it just shut off (but could be turned back on without a problem.)

Something looks like it's on its way to failure, but I don't know where to start looking.

[freakaftr8]

Re: Samsung PN51F8500 slow pixel response

Does the TV turn off with VS raised or back in spec? Sometimes if VS goes over spec to a certain amount the power supply will shut it down

I would look for bad solder connections on power supply especially the mosfets underneath the aluminum heat syncs.

[ranergeo]

Re: Samsung PN51F8500 slow pixel response

It does it with voltage at spec or above. I'll go check those solder connections, as I've read elsewhere that they're problematic on these sets.