Samsung PN50C550 single horizontal line

[YamahaFreak]

This TV has been working flawlessly for a few years now, ever since I got it secondhand and replaced the failed power supply. I turned it on today and there is suddenly a single pixel tall horizontal solid black line, almost exactly halfway up the panel, running all the way from edge to edge. It is consistent and does not move, flicker, or change color. I went inside and reseated all cables and connectors - no change. Ideas? Please don't tell me my panel is bad because I love this TV!

[kf4rca]

That's a plasma. I'd check power supply voltages first.

[YamahaFreak]

Originally Posted by kf4rca

That's a plasma. I'd check power supply voltages first.

I'm not sure how the power supply could be at fault. The only defect is that single pixel dead line, and the power supply has already been replaced and verified working.

I'm thinking it might be a buffer issue. Otherwise, I'm out of ideas.

[kf4rca]

Here's a link to a samsung plasma training manual:
https://www.eserviceinfo.com/downloa...0%5BTM%5D.html
I don't think it's panel. My experience is the panels are pretty robust unless, of course, it's cracked.

[YamahaFreak]

Originally Posted by kf4rca

Here's a link to a samsung plasma training manual:
https://www.eserviceinfo.com/downloa...0%5BTM%5D.html
I don't think it's panel. My experience is the panels are pretty robust unless, of course, it's cracked.

Thanks for that link, sure to be useful in the future! Panel is definitely not cracked, as it's running (otherwise) just fine, no other changes, and no physical shock has been dealt to it. I did once read about issues with cracks spontaneously developing in Samsung plasma panels, but have not seen any evidence of that happening on this one.

[kf4rca]

Try soldering up the driver boards. They run pretty hot and can develop cold solder joints.
Where's JohnCT? I think he's an expert on these.

[JohnCT]

Originally Posted by kf4rca

Try soldering up the driver boards. They run pretty hot and can develop cold solder joints.
Where's JohnCT? I think he's an expert on these.

Sorry, AWOL...

With a plasma, a single horizontal line is either the buffer board (95%) or the display itself. I can't honestly recall seeing a display itself cause this but some training manuals over the years mention it, so I am as well.

John

[YamahaFreak]

Originally Posted by JohnCT

Sorry, AWOL...

With a plasma, a single horizontal line is either the buffer board (95%) or the display itself. I can't honestly recall seeing a display itself cause this but some training manuals over the years mention it, so I am as well.

John

A little update: the line is still there, and has not grown, moved, or otherwise changed at all. Definitely a fixed anomaly. I'm a bit concerned about it affecting the panel as far as burn-in is concerned.

[JohnCT]

Originally Posted by YamahaFreak

A little update: the line is still there, and has not grown, moved, or otherwise changed at all. Definitely a fixed anomaly. I'm a bit concerned about it affecting the panel as far as burn-in is concerned.

The line is unlit, so if you ever replace the scan buffer board to restore a complete pic, you'll find the line is now a bit brighter and a bit bluer than the rest of the display, depending of course on how long the display is run with that one line unlit.

John

[YamahaFreak]

Originally Posted by JohnCT

The line is unlit, so if you ever replace the scan buffer board to restore a complete pic, you'll find the line is now a bit brighter and a bit bluer than the rest of the display, depending of course on how long the display is run with that one line unlit.

John

I actually wanted to go that route (replace the entire buffer board) but none seem to be available. Alas...

[JohnCT]

Originally Posted by YamahaFreak

I actually wanted to go that route (replace the entire buffer board) but none seem to be available. Alas...

I have one if you want it - I don't take these in anymore for service.

Part number LJ92-01729A

A couple of caveats. The 50C550 is a 1080P panel and the ribbons from the panel to the buffer board are a bit difficult to remove and difficult to seat in the connector. When I install them, I use an Optivisor to make sure the ribbon's two notches are seated fully down in the connector. They may look good at first but when you see them with magnification, you'll see what I'm talking about. If you're nearsighted then this won't be a problem.

This board was marked good by me which means it was either pulled from a running panel or tried in another panel and verified, so it *should* be good.

If you want it, it's yours for the asking.

John