2008/9 Samsung LN55A950 Displaying Horizontal Lines

[killjoy2013]

Hi everyone. I just joined the forum - first post - need some help/advice. I fairly techinical/handy with electronics, but this my first venture into troubleshooting and fixing a flat panel TV.

The patient: A 2008/9 era Samsung 55" LED backlit LCD. Model: LN55A950

The issue: It's displaying black, horizontal lines across the entire screen. The lines appear to be 3 pixels wide, approximately every 1/4" uniformly down the screen. The lines are little more pronounced on the left of the screen and slightly less as you move right... but the lines run across the entire screen horizontally, and vertically.

Troubleshooting: The problem persist even when light direct pressure is applied to the panel/pixels with my finger. It also doesn't seem to be a tension/pressure issue on the perimeter of the screen (or if it is, I can't find it). It displays the issue consistently across all colors, all inputs, all built-in screens, logos, displays, etc. It displays the issue w/ no inputs hooked up, and when powered from any 120V plug (inc. the one that has worked fine for 4 years). I've disconnected both ends of the LVDS cable between the Tcon & dimming board, blew it out w/ compressed air and reconnected - didn't help. The cable appears to be in good shape visually - no way to test it.


Just from Googling and reading online, it seems like a lot of these 2008 era Samsung LCD suffer from this same issue. I need some advice on what to do next. My top 2 suspects are the Tcon board or the LVDS cable, but these are just novice guesses from a DIY'er. I'm really hoping it's not the panel - it would be a shame for a TV this nice to be junked. The uniformity of the lines tells my gut it's a signal issue though, not the panel... but this is just me guessing.

Any suggestions? Could be it the Tcon? Should I try replacing it? And if so, should I also replace the LVDS cable at the same time?

[tom66]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

It looks like a T-con board issue to me.

[killjoy2013]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

Thanks Tom. Any suggestion on where to source a new Tcon from? I can't seem to find a new one online. Or should I just go after a used/tested one? Shop Jimmy is out of stock, but I can get a used one from TSM for ~$80. I heard that Samsung won't sell one separately from the panel.

p/n: LJ94-02432G

[tom66]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

Used and tested is fine, but the testing is usually very basic, so be aware getting a faulty board is possible. Do check the return policy that those places have.

[killjoy2013]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

UPDATE: No luck. I replaced the T-con board tonight (as well as it's separate cooling fan since it was looking worn) and it's still doing exactly what it was doing before.

What's the next step? LVDS cable?

[tom66]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

Main board or panel is at fault, then. Assuming the T-con you got is good. Do you notice any change in symptoms at all?

[killjoy2013]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

Thanks Tom. As far as I can tell, it's showing the exact same symptoms as before T-con board swap. Alternating a 3 pixel horizontal grey/black line, then a 3 good pixels (the picture), then 3 pixel grey lines, 3 good pixels, etc.

I've attached a picture of the mainboard. I don't know if this is the same on all TVs, but the dimming board (i think that's what it is) is in the signal path between the main board and Tcon. Any way the dimming board could be causing issues too? Just asking based solely that it's in the signal path. The LVDS cable going off the top of the picture heads to the Tcon.

Let me check out price & availability for another mainboard. I really like this TV, but just debating how much $ to get into this to try to fix vs. calling it. If it's the panel, the TV is DOA. I think I may recall hearing that there was a Samsung recall/class action for bad capacitors on this era TV... though I don't see any obvious signs (bulging, etc.)

[tom66]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

This problem isn't caused by bad capacitors.

Yes the dimming board could cause it, interesting, is this an LED backlit TV?

I also notice the main board has the 120Hz motion interpolator, instead of the typical location on the T-con board. So it could be either dimming board or main board, assuming the T-con is good. Very difficult to tell!

You could most likely get $150 for this with the shown fault if listed on Craigslist or eBay, if you do decide not to fix it.

[killjoy2013]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

Tom,

Yes, LED backlit with local dimming. I've attached a couple close ups of the dimming and main boards, if it helps. There's also a 4th board, a backlight inverter, at the bottom center of the TV (though I'm not suspecting it's part of the issue).

Dimming board is ~$48 new, ~$29 used.
Main board is ~$250 new, ~$100 used.

Any suggestions on which to start with probability-wise? Otherwise, I'll start with the dimming board since it's cheaper and easier to replace... unless you think the MB is much more likely.

[tom66]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

I definitely think the main board is more likely. The dimming board just looks to pass through the signal, extracting the information it needs (brightness in certain areas for LED dimming), whereas the main board has a lot more processing on it.

[killjoy2013]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

I ordered a main board from an online store tonight that claims to have 1 in stock, new in box - $180. I figured this is the last shot and would rather go with a known good board vs. gambling with a ~$75 used one. Should be here towards the end of next week and I'll report back... hopefully this does it.

[brainmetz]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

My samsung LN55A950 just started doing the same thing. What did you discover caused the problem?

[killjoy2013]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

Tom: I swapped the main board out with another used (but 'tested') one. It did not resolve the problem. The symptoms remain exactly the same - nothing new, but nothing fixed either. Seems like the MB is not the issue.

Any thoughts on what to try next? Is worth swapping the dimming board to see what happens? I've wiggled all of the LVDS cables with the TV powered up trying to see if it's a bad cable, but that doesn't appear to be the case. Guessing it's either the dimming board adding interference into the signal, or, I guess, the panel itself (?).

My samsung LN55A950 just started doing the same thing. What did you discover caused the problem?

Welcome to the party! I'm still working on the diagnosis. It's looking more like the panel itself is at fault, but I'm not sure if the symptoms support that conclusion (yet).

[killjoy2013]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

I just ordered a new dimming board - will report back when I get it. I think this is the last shot - must be the panel itself if the dimming board doesn't do it.

[brainmetz]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

I replaced the TCONN, cables, motherboard and dimming board and mine still does the exact same thing. I did notice a small hum coming from the power board and after examining it, I noticed one of the capacitors is very slightly swollen. Could this cause the problem we are having?

Thanks

[RJARRRPCGP]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

Replace the caps pronto! Do it while it's still got life!

[tom66]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

I doubt a bad capacitor would cause this, can you show a picture of the slightly bulging cap though? It may be a panel defect, nothing that can be done about that unfortunately.

[TallCoolOne]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

Interesting timing for all this, I have the exact same panel which also just started doing the exact same thing today. Three of us with the same TV that get the problem all approximately at the same time? conspiracy perhaps

Anyway, very interested to hear what you find out. After googling around I saw a post on fixya where one user says:

"I have similar issues with my Samsung TV model LN55A950... all I did was take the back cover off...unplugged the two wide ribbon cables of the panel from the T-Con board, then turned it on...I waited for a minute until everything normalized. atfirst, all i see were similar lines...horizontal pin stripes on white background...white background because the panel is not connected to any image source. Then all lines are gone, after the 'normalization." you should only see white all through out. I then turned the unit off...connected the two cables back, turned it back on...voila! my TV is back to normal viewing, no more lines!!!"

Does this normalizing thing make any sense??

thanks!

[brainmetz]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

I tried the normalization thing and it didnt work for me. I just talked to a repair company who said it sounded like the part the tconn connectors plug into on the lcd is bad and there isnt anyway to fix them besides a new lcd panel which isnt cost effective. My tv is mounted on a stand and has not moved so I dont understand who those connectors went bad. Does anyone have any advice besides a new tv? And them what to do with this one, trash it?

Thanks

[killjoy2013]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

Interesting timing for all this, I have the exact same panel which also just started doing the exact same thing today. Three of us with the same TV that get the problem all approximately at the same time? conspiracy perhaps

...

Does this normalizing thing make any sense??

Welcome to the party. I suspected this is a systemic problem. There's many hits on Google when searching the symptoms + model #, but no definitive answers. Hopefully this post continues to help others.

FYI: I also saw that post, and tried the normalization thing... no luck.

I replaced the TCONN, cables, motherboard and dimming board and mine still does the exact same thing. I did notice a small hum coming from the power board and after examining it, I noticed one of the capacitors is very slightly swollen. Could this cause the problem we are having?

On my unit, there's a very faint, high pitch whine/hum coming from the top center/right portion of my power board. It sounds like it's coming from the transistor rail (on the heatsinks), but the noise is likely coming from the power transformer that is just to left of the transistors, also in that same portion of the board.

In that same area of the power board, there are several caps, and yes, the end cap of one of mine also appears to be a little swollen and puffed out. You can kinda see it in my attached picture. Although, while I'm not an EE, I don't see how a bad cap on the power board would be causing the picture issues as documented above.

I just talked to a repair company who said it sounded like the part the tconn connectors plug into on the lcd is bad and there isnt anyway to fix them besides a new lcd panel which isnt cost effective. My tv is mounted on a stand and has not moved so I dont understand who those connectors went bad.

Same here - the TV has been wall mounted for 3 years before this problem started - nothing to do with motion. And while I'm not sure about the validity of the repair tech's answer, I think I've come to the same conclusion - the panel itself is bad and is not cost effective to replace. However, I WELCOME someone else here to prove me wrong... I really like(d) this TV.

I doubt a bad capacitor would cause this, can you show a picture of the slightly bulging cap though? It may be a panel defect, nothing that can be done about that unfortunately.

Agreed. Suspect cap at the red arrow. Can't really see the concave-ness, but you can definitely see the glare difference between the top 2 caps and the bottom one, all of which are identical caps.