SAMSUNG LN40A650 (purchased 2008) -- weird visual glitches. - AVS Forum
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post #1 of 7 Old 08-14-2012, 11:41 PM - Thread Starter
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Hello,

I purchased this TV in 2008, and it's been working fine until recently.

I haven't been able to find anyone reporting a similar problem, but here is the description.

- I'll notice a weird glitch, like a small square of static suddenly appearing in the middle of the screen (otherwise, the image looks fine), and thne the TV flickering for a second, then a thin band appearing at the very top of my screen, directly beneath the bezel.

- TV also turns black sometimes.

- This usually happens about 20 mins or so after the TV is first turned on.

- That line/band at the top of the screen goes away when I turn the TV off and then on again.... I haven't seen the problem reoccur after turning the TV off. It only reoccurs the next day, when I turn the TV on for the first time in the day.

What could this be?
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post #2 of 7 Old 08-15-2012, 04:46 PM
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Quote:
Originally Posted by ln40a650problem View Post

Hello,
I purchased this TV in 2008, and it's been working fine until recently.
I haven't been able to find anyone reporting a similar problem, but here is the description.
- I'll notice a weird glitch, like a small square of static suddenly appearing in the middle of the screen (otherwise, the image looks fine), and thne the TV flickering for a second, then a thin band appearing at the very top of my screen, directly beneath the bezel.
- TV also turns black sometimes.
- This usually happens about 20 mins or so after the TV is first turned on.
- That line/band at the top of the screen goes away when I turn the TV off and then on again.... I haven't seen the problem reoccur after turning the TV off. It only reoccurs the next day, when I turn the TV on for the first time in the day.
What could this be?

Do you have any new equipment? Are you running a comcast HDDVR? Is it new? Does this happen with cable/sat TV and also with blu ray?

Here are some thoughts until you answer the questions above. Your #1 and 2 problems seem heat related, since in #3 you say it happens 20 minutes in. It takes awhile for heat to build up (say 20 minutes).

I have a 4 year old 52A860 and I get blackouts for a second or so occasionally (but can hear sound) when watching recordings on my comcast HDDVR running thru a Denon receiver, both in a small equipment rack near the TV. In the summer, I make sure A/C and/or cool furnace fan air is directed from a nearby vent toward the equipment cabinet. I block the vent in winter to keep hot furnace air away. The peripheral equipment runs too hot, cooling it solves the problem. No problem with Denon off (it has HDMI pass thru), no problem with blu ray, no problem watching live TV thru Comcast box. Try a small fan to prove/disprove for your setup.

Check to see if the fan in the TV is working and not clogged. Also, make sure the power cord and the HDMI cord are firmly pressed into the sockets.

Also, make sure you're on 16x9 for TV which pushes closed caption data off the top of the screen. It usually appears as a line.
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post #3 of 7 Old 08-15-2012, 05:27 PM - Thread Starter
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Thanks for the reply. I think you're right -- it seems heat related.

You know what the weird thing is? I moved recently, and I accidentally plugged in a 125V power cord into the TV, and it was working fine, and then I saw the issue. I realized my error and plugged in the proper power cord, which is 120V, and the TV worked fine for a week -- no issues at all. Then, suddenly, the issues returned.

It's puzzling. I'm not sure why the switching of the power cord made the issue go away for a week, or if it's just a coincidence and the cord has nothing to do with it. Either way, the issues are back.
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post #4 of 7 Old 08-15-2012, 05:29 PM - Thread Starter
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I also have the TV hooked up to a new surge protector, and this was the case for the wrong plug and the right plug. I was contemplating plugging the TV into a wall outlet instead, but I don't know if that's the best idea...

Also, I called Samsung. There were some doubts from some of the reps I spoke with, I think, about whether or not what I am describing above really indicates a capacitor issue (which, as you may know, they are obligated to fix for free for TVs manufactured before Dec. 31st, 2008). Because of this I'm worried that when the service technician comes, he'll discover the problems I've been experiencing have nothing to do with the capacitor and I'll be charged for the visit.

What do you think? Do the visual glitches above indicate a capacitor issue? One Samsung rep told me that the capacitor is essentially the part that powers on and off the TV. Thus, when you hear clicking (one of the symptoms listed on Samsung's website), that's the capacitor repeatedly trying to turn the TV on. This is also why the other symptoms include the TV cycling on and off, taking a long time to power on, etc.

I don't have those symptoms -- I guess the TV takes a long time to turn on, but it's always done that, or so it seems. I can't really tell if there has been a difference. The TV itself doesn't cycle on and off, but the image does occasionally disappear as part of the visual glitches I described above. For instance, the TV image will suddenly vanish, leaving me with a black screen, then it will restore the image in a moment, but with a weird, jumpy line at the top of my TV. Does this sound like something that could be traced back to the capacitor?
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post #5 of 7 Old 08-15-2012, 10:23 PM - Thread Starter
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I decided to plug the cord into the wall outlet (rather than the surge protector) before use today, and I found that no issues came up.

Could it really be that the surge protector is at fault? Since moving, it's essentially the only thing that's changed about the TV. I've added a surge protector. I thought it was that I was using a cord with the improper voltage, but once I changed the cord to the right one, the issues persisted.

The issues only started cropping up once I started using the surge protector. Now that it's plugged into the wall, I'm not experiencing the issues...so far, at least. Just finished using the TV for a few hours. I find it odd that a surge protector could create those glitches, but perhaps that's what happened.
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post #6 of 7 Old 08-16-2012, 01:40 PM
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I'm no electrical engineer, but I don't think the cord made any difference.... your wall outlets in a home are all 15 or 20 amps which is OK for the TV. I think you should use a surge protector, but it sounds like you got a bad one. Try a new one and, if it works, you're all set.

PS: Comcast said not to run their coax cable thru a surge protector.
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post #7 of 7 Old 11-11-2012, 07:34 PM
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Today I just noticed the same thing on my Samsung TV.

I took your advice and unplugged from the surge protector and straight into the wall. That fixed the problem!

Thanks for posting!
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