Smudge when display warms up

Discussion in 'Mac Accessories' started by coldwaves, May 7, 2013.

  1. coldwaves macrumors regular

    May 30, 2011
    I have a almost 5 years old 24 inch cinema display. The display will show a dark smear vertical line/smudge on the left side when the display warms up. The smudge is not there when the display is cold, i.e. when I first turn on the display, the smudge is not there. But it will show up when the display is warm. If I turn off the display for a while, it disappear. The smudge is most visible in a green or grey(like when you turn on the computer) background. I cannot see it in blue or red or white or black background.

    The smudge is very similar to the one here:
    But mine are not that obvious and is more straight.

    I have cleaned both the outside and inside of the glass panel and make sure it is not dust on either side of the glass. Anybody has idea what could be the cause?
  2. thedeske macrumors 6502a

    Feb 17, 2013
    That looks just like the much discussed "dust inside the panel layer" on iMacs over the last few years.
  3. coldwaves thread starter macrumors regular

    May 30, 2011
    Yes, it does look like the much discussed dust issue. And I can probably pull open the panel and clean it. The confusing part is that the smudge only appears when the display is warm. It is not visible at all when it is cold. That doesn't seem to be dust. Should it be always visible if it is dust inside the panel?
  4. Washac macrumors 68020


    Jul 2, 2006
    I have had two Apple displays do this, both on that side of the screen, my first iMac did this and it was not dust behind the frontpanel it was inside the LCD layers and was there from cold.

    My second Apple display to do this is my 24inch Apple Cinema display, it appeared slowly over time as in the iMac and was visible when the machine was cold or hot. This display was sent back under Applecare as was the Imac, the Imac is still OK but it has reappeared on the 24inch cinema display.

    As I say on both displays it was not dust behind the front panel but inbetween the LCD layers.

    So that is three LCD panels in total which have had this issue and one still has.

    I have vowed to never buy another Apple display
  5. coldwaves thread starter macrumors regular

    May 30, 2011
    That's unfortunate. Mine are only visible when it is warm. I cannot see anything when it is cold. So I would think it is not dust but I do think it is something related to the LCD panel or the backlighting. My Macbook Pro is a little less than 2 years old and it has a slight dark spot in the center. But I have a 7 year old 20 inch cinema display in my office and that one is perfect over all these years.
  6. grayskyz macrumors regular


    Nov 21, 2008
    Los Angeles
    There's more than a few discussions going on about this. I had mine replaced a month ago under warranty on my 27"

    The nice thing is if you tell them to do a house call they are supposed to under AppleCare if you request it.

  7. thedeske macrumors 6502a

    Feb 17, 2013
    Hard to say. I had that and some nasty corner dust on a 27 imac. Sometimes the lines would appear in a place on the right side when it was really hot and sometimes not. Got it replaced.
  8. coldwaves thread starter macrumors regular

    May 30, 2011
    It is good you have the warranty! Mine are almost 5 years old and it is clearly out of any warranty. Since it is not a huge problem, I guess I will just live with it.


    It does seem to be a heat related issue. My display has been out of warranty for a long time. Well, it is a almost 5 year old display so a little problem is acceptable to me. Just want to ask if there is any solution I can try to fix it. It seems to be the panel problem where replacement is the only solution. Since the smudge is not that obvious, I will just live with it until it really annoys me.
  9. thedeske macrumors 6502a

    Feb 17, 2013
    I was lucky to get mine replaced (free) but did a lot of research (here, I think) and really considered opening the panel to clean it. There's no promise you get it back to new, but people are doing it. I wouldn't want to try unless I had a second system around.
  10. coldwaves thread starter macrumors regular

    May 30, 2011
    Thank you for your suggestion! I would not open the LCD panel itself unless the smudge is too obvious that I cannot live with. It will be pretty hard to avoid dust and lint if I open the panel. Cleaning the inside of the front glass panel seems to be difficult if you want to get rid of all the dust. So I will not take the risk to introduce even more dirt inside the LCD panel.

    After observing the display a little more, I find that the smudge is a very regular rectangular shape. This does not seem to be dust since it is not likely to form such a regular shape. I suspect maybe something behind the LCD panel touch or interfere with the LCD panel. This make sense since the smudge only appear when the display is hot. I will probably open the glass panel and the LCD panel out to see what's behind. This seems to be easy since I only need to use the suction cup for the glass and six screw for the LCD panel. I will report back if I find the real problem.
  11. AppleNewton macrumors 68000


    Apr 3, 2007
    1 Finite Place
    definitely not dust. it is smudging/discoloration. only resolution is to replace the LCD Panel.

    This has happened to three lcds in my 2011 27-inch iMac. Sometimes on one side and now on the left.
  12. coldwaves thread starter macrumors regular

    May 30, 2011
    Just want to update what I find after exploring this issue a little more. As I found in the above post, the smudge/dark shadow seems to be very regular rectangular shape. The technican guide of cinema display mentions that the tight screw or something on the back of LCD panel touching it could create interference. So I take off the glass panel and the LCD panel to examine the backside. It seems the shadow matches the location of metal frame/bracket attach to the backside of the LCD. Nothing else seems to be loose. So I just re-assemble everything but this time, loosen the screw that hold the LCD to the frame just a little bit. Now, this seems to help! The smudge seems to be little and I cannot see the rectangular shape anymore. There are still a little bit of it and I suspect this is just due to the age of the display.

    So in a word, if you experience a very similar issue where you see a very regular shape shadow, you might try to loosen the screw a little bit to see if it helps.
  13. thedeske macrumors 6502a

    Feb 17, 2013
    Nice work. Guess something settled in over time to create the pressure.
  14. jenzjen macrumors 68000

    Aug 20, 2010
    Strange, my issue actually appears on a cold display and goes away as the monitor gets warm.
  15. coldwaves thread starter macrumors regular

    May 30, 2011
    It seems the smudge is coming back. I attach a picture where you can clearly see the dark line (the dark line on the left. The right are just reflection of the window shade:). It is now mysterious to me what the problem is. Again, the dark line is not there when the display is cold. It only appear when the display is on for a while and is warm. It will disappear if I shut off the display and let it cool for a while. But it will re-appear when it warms up. So strange to me.

    Attached Files:

  16. Revearti macrumors member

    Oct 29, 2011
    I'm noticing a gray smudge on the bottom-left of my five year old 24-inch Cinema Display. From what I read on the Apple Support forums, it's a burn-in problem. If it gets worse, I'll consider paying Apple to fix it depending on the cost.

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