Plasma Damage....Can Anything Be Done? - AVS Forum
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post #1 of 26 Old 10-16-2013, 11:42 AM - Thread Starter
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Hello,

I have a Samsung Plasma model PN43D490 and over the past several months I have noticed some issues with the image. Specifically on the left third of the screen I see image issues. It looks like the picture is flickering. It's not constantly there, but I'd say 50% of the time I turn on the TV or switch a channel it happens. This happens on multiple devices connected to the TV (HTPC, Cable Box). It happens regardless of the color it is displaying (IE it's not just on a white background or other specific color).

I am considering buying a new set but I wanted to see if anyone could offer advice on how to fix this issue. The TV's less than 2 years old and I'd hate to get rid of it if there was something to do to fix it.

Thanks in advance for your input!

R.
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post #2 of 26 Old 10-16-2013, 12:39 PM
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Probably can be fixed -- could you provide a picture/video of the issue? I believe (from memory) this is due to an internal power supply fault. Vs output falling low.
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post #3 of 26 Old 10-16-2013, 08:07 PM - Thread Starter
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00004-1-1.zip 1969k .zip file

Thank you for your response. Please see attachment. You can clearly see flickering in the left third of the screen. Do you think anything can be done?
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post #4 of 26 Old 10-17-2013, 04:30 AM
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Are you talking about that slight pink tinge and flicker to the image? The bars on the camera image are likely due to how the plasma screen refreshes, and shouldn't appear visible to the human eye.

The pink tinge/flicker can usually be fixed by adjusting the Vs voltage. You will need a digital multimeter capable of measuring up to 300V DC (most are.) You can buy one for around $10 if you need to. Take the cover off then take a picture of the power supply board. It is in the centre of the TV and the AC power cord connects straight to it. There's also a sticker on the internal metal plate marked with the SAMSUNG logo and with Vs, Va, -Vsc and Ve voltages, get a picture of this too please.
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post #5 of 26 Old 10-17-2013, 07:07 AM - Thread Starter
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Tom,

Perhaps I didn't capture a long enough clip. I am talking about the image flicker on the left third panel of the screen. I will snap those shots and respond accordingly. This probably will take me a couple days to get those snapshots and longer video.

Thanks I really appreciate the help!
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post #6 of 26 Old 10-18-2013, 09:22 PM - Thread Starter
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Here is another take of the issue using a white screen as a background. There is a green line running from top to bottom through it too. 00010-1.zip 2027k .zip file
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post #7 of 26 Old 10-19-2013, 03:56 AM
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Yes, I see what you are talking about now.

That does look like underdiffusion, usually caused by low Vs, Ve or -Vsc voltages.

One thing you should do before adjusting anything is apply the latest firmware update from Samsung. Sometimes it can fix odd issues like this. If not, you will have to take the back cover off and get those photos so the adjustments can be made.
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post #8 of 26 Old 10-19-2013, 05:01 PM - Thread Starter
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I did locate the latest firmware version which I already have on this TV. Please find pics attached.....thanks! 20131019_173333.zip 3728k .zip file
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post #9 of 26 Old 10-19-2013, 06:00 PM
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OK. On your power board you have a metal pad marked VS-TP, do you see this?

Carefully set your meter to the highest DC voltage range for example 500V, 600V or 1000V. DC is marked by a solid and dashed line. If it has autoranging capability, set it to autoranging volts DC. Red probe on meter goes in the jack marked VDC or VOLTS and black probe goes in COM. Make sure it is not set to volts AC, which is marked with a squiggle like this "~".

Place the black probe on part of the metal chassis -- somewhere it will go safely. For example the wall mount bracket is a good place. This is the cold ground.

The red probe should then touch the test point. Make sure you can touch the test point without slipping (do this with the set turned off first.) Make the measurement on that point with the TV running. Try testing on a dark image -- a dark movie, or the "No Signal" pane. Then try testing on content which normally makes the problem appear. See if there is a change. The voltage should not drop by more than about a volt and it should match the panel sticker within 2 volts (208 to 212 V.)

Careful: You are working around a power supply which is LIVE. The board exposes high voltages, not only the Vs but also the mains voltage. Do NOT touch anything on the power board while it is plugged in, or shortly after turning off the set. Many of the heatsinks on the board are live and can carry deadly voltage. Always have another person in the room to supervise in case you make an error.
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post #10 of 26 Old 10-19-2013, 07:01 PM - Thread Starter
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Thanks Tom,

You are providing me a great tutorial and it's very much appreciated. I'm curious if the voltage does vary more than 2 volts outside the panel sticker, what does this indicate? I will freely admit I am concerned about this testing due to (a) the damage I can do to the TV and (b) the damage I can do to myself!

If we're working under the theory the voltage is the issue, what part would I need to replace &/or tweak it?
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post #11 of 26 Old 10-20-2013, 06:23 AM
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Quote:
Originally Posted by Corkscrew View Post

Thanks Tom,

You are providing me a great tutorial and it's very much appreciated. I'm curious if the voltage does vary more than 2 volts outside the panel sticker, what does this indicate? I will freely admit I am concerned about this testing due to (a) the damage I can do to the TV and (b) the damage I can do to myself!

If we're working under the theory the voltage is the issue, what part would I need to replace &/or tweak it?

If it drops while on the brighter scene by more than about a volt, it is a power board issue. If it is just plain wrong to begin with (independent of image), it is just set incorrectly and can be adjusted carefully using the VS-ADJ point.

If the voltages are found to be fine, then the next place to look is the -Vsc voltage on the Y-main which can also cause this issue. I note this panel does not specify what Ve is, so that can't be tested.
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post #12 of 26 Old 10-20-2013, 04:05 PM - Thread Starter
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Do you think replacing the power board would resolve both of these potential problem sources?
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post #13 of 26 Old 10-21-2013, 10:13 AM
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Quote:
Originally Posted by Corkscrew View Post

Do you think replacing the power board would resolve both of these potential problem sources?

In most cases yes, but first I'd suggest you test to see if it is the cause.
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post #14 of 26 Old 10-21-2013, 12:40 PM - Thread Starter
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Considering the circumstances I have located a "refurbed" power board on eBay. Yes yes I know refurb is not great but they're really cheap and I think it's worth a shot.

That being said, understanding this may not resolve the issue, I'd like to proceed with replacing the power board. Can you help me out with that? My main concern (naturally) is I don't electrocute myself. Is this a dangerous thing to be doing?
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post #15 of 26 Old 10-21-2013, 12:48 PM
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Do you want to do a test using a multimeter first? It could be either power board or Y-main at the moment, and it's quite likely it can be corrected by a simple adjustment. Can you borrow a multimeter off a friend? Even ones for automotive work usually do fine, as long as they can measure high voltage.

Replacing the power board is not hazardous after the main 450V capacitors have been discharged. I will highlight where to do so on a picture if you decide to go that way.
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post #16 of 26 Old 10-21-2013, 01:08 PM - Thread Starter
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Ahhh I see Ok. The testing worries me because of the aforementioned reasons. I am taking it that a power board will not fix the Y Main issue, is that correct?

The power board is really cheap (less than $15 US) as I mentioned and I'd rather spend the $ to try something non-hazardous as opposed to possibly juicing myself. I know very little about electricity and with my luck I'd juice myself pretty well. I also think that the testing would be difficult due to the fact that it's hard for me to distinguish when that screen flickering occurs. It seems to be totally sporadic and in short bursts. I think it would be hard to get an accurate measurement as a result.

Again I appreciate all your time and assistance in this matter. If you could highlight what to do on a pic that would be great, thanks!
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post #17 of 26 Old 10-21-2013, 01:23 PM
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Yes, a power board will not fix a Y-main issue and vice versa. It will also not fix a misadjustment problem.

Attached is a picture.

capshort1.jpg 1810k .jpg file
  • Unplug the TV. Leave it alone completely for 30 minutes.
  • Place a metal insulated handle screwdriver across each pair of indicated terminals. (A pair is underneath each large cylindrical object -- a capacitor.) A small spark may be noticed -- this is OK. Make sure you're thorough in shorting the terminals out.
  • Note down the BN44 or LJ44 number on the board. This is your PBA code and part # to order from.
  • Remove the screws and put the power board to the side. Keep the screws! One good method is to install the screws in their old holes. Hold the board by the edges.
  • Order the new board.
  • Install the board, also holding it by the edges where possible.
  • Turn on the TV and verify if the problem is resolved. If it is not, you WILL need to do a multimeter test unfortunately to check the Vs and -Vsc.
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post #18 of 26 Old 10-21-2013, 01:42 PM - Thread Starter
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Thanks Tom. Any specific length of time I need to leave the screwdrivers across the terminals?
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post #19 of 26 Old 10-21-2013, 01:57 PM
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Quote:
Originally Posted by Corkscrew View Post

Thanks Tom. Any specific length of time I need to leave the screwdrivers across the terminals?

A second or so.
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post #20 of 26 Old 10-29-2013, 06:11 PM - Thread Starter
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Back with an update.....replacing the motherboard has not appeared to fix my issue. The flickering seemingly changed a little as to how and when the it flickers, which I find a little strange.

I may try going the voltage tester route and will give you an update per your instructions on how to measure, thanks again.

Ryan
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post #21 of 26 Old 10-29-2013, 07:22 PM - Thread Starter
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Or would replacing the Y-Main fix the issue at this point since the MOBO was not it? It seems to me like there are 3 possible fixes.....MOBO (not it), Y-Main, or Voltages. You had mentioned the Voltage issue would be a either due to MOBO or "if it is just plain wrong to begin with (independent of image)". Do voltages go "out of whack" so to speak or is this something that would have occurred from day 1 on the TV? Would replacing the MOBO (done) and Y Main effectively be the same as testing/adjusting the voltages?

Please let me know your thoughts, thanks.

Ryan
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post #22 of 26 Old 10-29-2013, 07:30 PM
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MOBO? You mean power board? Or the actual main board, with the video inputs on it?
The voltages can be incorrectly set at the factory and humidity/thermal expansion can cause the adjustment points to drift.
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post #23 of 26 Old 10-29-2013, 07:42 PM - Thread Starter
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Tom,

Sorry I meant power board....can you tell I work in IT? This TV worked fine for close to 2 years so do you think it's safe to rule that out? I can't speak as much to humidity/thermal expansion except to say this TV is in a basement, which typically has low humidity. If I purchased a replacement Y-Main, would that also be effectively replacing the voltage capacitors, or is there still the possibility that after replacing Y-Main that the problem will still exist?
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post #24 of 26 Old 10-29-2013, 07:46 PM
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You'd need to adjust the replacement board to the same spec as your current panel, because they come from different panels, each are set slightly differently.
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post #25 of 26 Old 10-29-2013, 08:01 PM - Thread Starter
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Ok....is that a relatively easy thing to do or is it complicated? Would that also be effectively replacing the voltage capacitors, or is there still the possibility that after replacing Y-Main that the problem will still exist?
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post #26 of 26 Old 10-30-2013, 03:26 AM
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You're not replacing anything, apart from the boards.
The voltage adjustments can be tweaked using a screwdriver easily enough.
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