Resolved G3: High-pitched noise, only when monitor is ON

Discussion in 'PowerPC Macs' started by GameX, May 30, 2014.

  1. GameX, May 30, 2014
    Last edited: May 31, 2014

    GameX macrumors newbie

    Joined:
    May 27, 2014
    #1
    Hi,


    I've noticed what cause this high-pitched sound I hear when I use my iMac G3 (slot-loading). I couldn't identify the problem first.

    It's the monitor that causes this...
    I installed SwitchResX for changing the resolution first - The G3 monitor seem to support a maximum of 1024x768. I plugged it to an external monitor (Which support a maximum of 1280x1024), and SwitchRedX allowed to use 1280x1024 with the external monitor.

    Choosing this resolution will work with the external screen, and cause the iMac screen to turn Off. And the high-pitched sound is gone!
    It's not related to the OS, because it does it during the Apple logo, and on Linux as well, when the monitor is ON.

    It's weird... Definitely hardware related, but I can't tell what's wrong (Not worth it to fix it for me, I'm curious about it).

    Thanks!
     
  2. FreakinEurekan macrumors 68040

    FreakinEurekan

    Joined:
    Sep 8, 2011
    Location:
    Eureka Springs, Arkansas
    #2
    Pretty common symptom of high voltage power supply failing on a CRT display.
     
  3. GameX thread starter macrumors newbie

    Joined:
    May 27, 2014
    #3
    So if I used a different power-supply (I believe only those from Apple would work!), the problem should be gone, right?

    The iMac was unused, left sitting in a shed for 8 years, if that's important to know.
     
  4. FreakinEurekan macrumors 68040

    FreakinEurekan

    Joined:
    Sep 8, 2011
    Location:
    Eureka Springs, Arkansas
    #4
    No, it's the internal power supply - the high voltage supply for the CRT, that converts the line power up to 20-30 thousand volts for the picture tube.
     
  5. GameX thread starter macrumors newbie

    Joined:
    May 27, 2014
    #5
    Thank you.

    I won't do anything to the iMac, it still work without the sound, when screen is off, connected to another monitor.
    Will mark the thread as solved.
     

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