robbfrombethesda
Level 1 (10 points)

Q: 2011 core i7 27" screen flicker at low brightness

Anyone else having this problem?  The screen flickers quite a bit at the lowest 4 or 5 brightness levels, or when the screen dims after idle time. 

 

I can't believe I have to haul this thing back to the store....

iMac, Mac OS X (10.6.7)

Posted on May 5, 2011 8:28 PM

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robbfrombethesda

Q: 2011 core i7 27" screen flicker at low brightness

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  • by HuntWorks,

    HuntWorks HuntWorks May 5, 2011 9:41 PM in response to robbfrombethesda
    Level 1 (5 points)
    Wireless
    May 5, 2011 9:41 PM in response to robbfrombethesda

    My 2011 27" iMac Core i5 (3.1 Ghz) is doing the same thing. I've turned off the screen dimming and ambient sensor to check - no change. I do NOT want to haul it in, either. I just got it this afternoon. Any thoughts, anyone?

  • by robbfrombethesda,

    robbfrombethesda robbfrombethesda May 5, 2011 9:56 PM in response to HuntWorks
    Level 1 (10 points)
    May 5, 2011 9:56 PM in response to HuntWorks

    I also turned off the automatic ambient light adjust.

     

    This is different from the flicker on the previous generation iMacs.  Its almost like the old 60hz interlaced CRT displays -- you can see it more in your peripheral vision.  It occurs constantly, though the magnitude of it seems to fluctuate.

     

    It occurs even on the gray and blue start-up screens so I don't think its an OS issue.

     

    Resetting the PRAM/NVRAM (hold command-option-P-R at boot) didn't help.

  • by Dr.Yes,

    Dr.Yes Dr.Yes May 6, 2011 5:06 AM in response to robbfrombethesda
    Level 1 (0 points)
    May 6, 2011 5:06 AM in response to robbfrombethesda

    Same here on the 21.5" entry model

  • by laundry bleach,

    laundry bleach laundry bleach May 6, 2011 8:07 AM in response to robbfrombethesda
    Level 5 (6,982 points)
    Safari
    May 6, 2011 8:07 AM in response to robbfrombethesda

    There is an iMac EFI Update and a update of Mac OS X 10.6.7 for the iMac available that you should probably try before anything else.

     

    Best of luck.

     

    Message was edited by: laundry bleach

  • by robbfrombethesda,

    robbfrombethesda robbfrombethesda May 6, 2011 10:26 AM in response to laundry bleach
    Level 1 (10 points)
    May 6, 2011 10:26 AM in response to laundry bleach

    The updates didn't help. 

     

    I've noticed in a brightly lit room I can't really see it.

     

    I found this in a Wikipedia article.  This is my first LED backlit screen so it might be an inherent problem.  Ugh.

     

    http://en.wikipedia.org/wiki/LED_backlight

    Flicker due to backlight dimming

    LED backlights are often dimmed by applying pulse-width modulation to the supply current, switching the backlight off and on again like a fast strobe light. If the frequency of the pulse-width modulation is too low and or the user is very sensitive to flicker, this may cause discomfort and eye-strain, similar to the flicker of CRT displays.[5] This can be tested by a user simply by waving a hand or object in front of the screen. If the object appears to have sharply-defined edges as it moves, the backlight is strobing on and off at a fairly low frequency. If the object appears blurry, the display either has a continuously-illuminated backlight or it is operating at a frequency that is too high for the brain to perceive. The flicker can be reduced or eliminated by setting the display to full brightness, though this has a negative impact on image quality and battery life due to increased power consumption.

     

     

  • by StephenBhm,

    StephenBhm StephenBhm May 10, 2011 5:47 AM in response to robbfrombethesda
    Level 1 (0 points)
    May 10, 2011 5:47 AM in response to robbfrombethesda

    I seem to be having the same problem. Brand new iMac 2011 Core i7 27".

  • by barisoktem,

    barisoktem barisoktem May 12, 2011 12:51 AM in response to robbfrombethesda
    Level 1 (0 points)
    May 12, 2011 12:51 AM in response to robbfrombethesda

    I have the same problem screen flickering and never come up to full brightness, when is brightness full in 1 minutes automatically flicker and brightness down, it's like not support full brightness or something...

    And when i change the brightness flicker again. It's looking hardware problem for me but i'm not sure because 2009 imac models had worsed flickering issues and Apple send update for this issues, maybe if we can wait they send another update for this thing...

  • by Edward Boghosian,

    Edward Boghosian Edward Boghosian May 12, 2011 1:42 AM in response to barisoktem
    Level 4 (1,395 points)
    May 12, 2011 1:42 AM in response to barisoktem

    Apple did have a flickering problem with a previous version of iMac and there were people, then, who said: "Wait for an update" or "Wait for a software remedy."  The only remedy is to return it.  Like last time, you may get another screen that flickers.  Then, the only remedy is to get your money back.  Then, no one came charging on a white horse from Apple headquarters with a solution and no one is going to come now.  The choice is yours.

  • by barisoktem,

    barisoktem barisoktem May 14, 2011 12:13 AM in response to robbfrombethesda
    Level 1 (0 points)
    May 14, 2011 12:13 AM in response to robbfrombethesda

    Yes you're right but i'm living istanbul/Turkey and when i take back my machine for repairing service they really don't know what is the problem and i had really hard time to explain vs.

    And repairing not working well here they change every part till problem going away, and the parts it's coming us or china and this period took at least one month for each part (logic, screen, RAM vs.)

    Thanks for reply...

  • by albe75,

    albe75 albe75 May 17, 2011 12:26 AM in response to robbfrombethesda
    Level 1 (0 points)
    May 17, 2011 12:26 AM in response to robbfrombethesda

    I have the same problem (in Switzerland). Just bought imac 27" i5, when dimming 2/3/4 bars the illumination of the panel vibrates like a candle..... at 1 bar is ok, at 5 or more is ok too.

  • by barisoktem,

    barisoktem barisoktem May 17, 2011 12:54 AM in response to albe75
    Level 1 (0 points)
    May 17, 2011 12:54 AM in response to albe75

    Mine is iMac 27" i7 2.93 Ghz model.

    And today eventually half of screen goes dark shadow. It's like my left eye slightly seeing.

    I really don't understand now i have to go service and i have to wait at least one or two months.

    And it's my second machine has the same problem first one is MBP.

    All of Apple LED screens are really really bad quality, bad bad quality, everytime i have to be change mac parts why i have to do this why is not working well i paid 1500$ for it. Is it not enough?

    I really don't understand.

    i'm using mac at least 20 years. But i start the thinking about the change the system.

    I'm not sure about Apple anymore.

     

    Sorry for my deficient english...

  • by Primalair,

    Primalair Primalair May 23, 2011 2:48 PM in response to robbfrombethesda
    Level 1 (0 points)
    May 23, 2011 2:48 PM in response to robbfrombethesda

    Same issue here... 27" imac mid 2011, 3.4GHz i7, 2GB Graphicmemory... flickering at low brightness. Anybody fixed this Issue by returning his Device or is this a common Issue at all new imacs and we have to wait for a Fix from Apple?

  • by albe75,

    albe75 albe75 May 23, 2011 3:03 PM in response to Primalair
    Level 1 (0 points)
    May 23, 2011 3:03 PM in response to Primalair

    Hi! I brought my imac back to the shop, explained the problem and changed with another imac 27 i5.

    The new one is perfect! No flickering, no "candle effect".

    I think it was an hardware problem.

    IMO don't lose your time waiting for a solution that maybe will never come... bring it back, take a new one and enjoy!

    It's a very nice computer!

  • by Primalair,

    Primalair Primalair May 23, 2011 3:12 PM in response to albe75
    Level 1 (0 points)
    May 23, 2011 3:12 PM in response to albe75

    Hey Abe75

    Well i've a Build to Order Configuration. I don't think that the Applestore can replace my Device directly in the Store and i've to wait a long time for my replacement.

    Greets Primalair

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