Recent noise in addition to buzzing when reducing brightness on Imac 27"?

Discussion in 'iMac' started by ejosepha, May 29, 2010.

  1. ejosepha macrumors 6502

    Joined:
    Jan 12, 2009
    #1
    My week 13 Imac 27" has always made the buzzing noise coming from the top left of the computer when brightness is reduced below 70%, but I really couldn't hear it much when sitting directly in front of the screen so I lived with it. Now, after having had the computer for almost 40 days, there is an additional noise that I first thought was a fan coming on, but I don't believe it is. It's not the original buzzing, but more like an increased fan noise, though the fans rpms remain at their original normal levels. I see that I can get rid of the noise by moving up the brightness to maximum, and then down to minimum a few times. This works, but then eventually the this new fan-like, or higher pitched noise kicks in again.
    Any ideas on what this could be. I realized that increasing the brightness for the buzzing was like turning a halogene lamp up so that the regulator stopped making a similar noise. But now this has been added to the problem.
    Again, it disappears after sliding the brightnes up and down a few times (the original buzzing always remains though at the lower brighntess).
    Any clues of what I am dealing with?
     
  2. Btom macrumors 6502a

    Joined:
    Nov 19, 2009
    #2
    Problem (probably unstable) led back lite power supply.
    Apple Care, Apple Care, Customer Relations, New Computer (in this order).

    Tom B.
     

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