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  1. #1


    Member Since
    Jan 24, 2011
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    Late 2010 Mac Pro 5,1 with 3.33Ghz 6-core, and 16GB RAM
    Unhappy MBP LCD Screen Humming Noise
    Hi All,

    I have a 2.16GHz Core Duo MBP and the LCD screen is making a humming / buzzing noise. If the display brightness is greater than 50% the buzzing stops and if it completely dark it stops, but from say 1% to 50% the buzzing gets worse the lower you go.

    I took apart the screen and installed a brand new display inverter board. That helped and was good for about a week, but it's happening again. I'm trying to figure out if the inverter board I got was bad, or if it is something else, maybe the bulb, or otherwise.

    Any recommendations?

    Some questions to pose...
    Are there any voltages, etc., to check on the boards somewhere to diagnosis the issue?

    If it is the bulb, do I need to replace it or can it be tuned; are they expensive?

    Anything else I might check into?


    Thanks for the input.
    Paras.


    MacBook Pro, Model A1175, 2.16GHz Core Duo, 2GB RAM, OSX 10.6.6, EFI Firmware 1.2

  2. #2

    chscag's Avatar
    Member Since
    Jan 23, 2008
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    Fort Worth, Texas
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    Late 2013 27" iMac, iPad 3, iPhone 6s+, iPhone 6+, 3 iPods, El Capitan
    I don't believe the buzzing is coming from either the inverter or the CCFD tube (backlight) since you changed out both. (The backlight is contained within the display assembly.) Check the positioning of the cables going from the logic board and inverter to the display. That includes the cable that carries video. There may be a grounding problem somewhere.

    For layout and take apart diagrams and instructions go to iFixit: The free repair manual.

  3. #3


    Member Since
    Jan 24, 2011
    Location
    New York City
    Posts
    81
    Specs:
    Late 2010 Mac Pro 5,1 with 3.33Ghz 6-core, and 16GB RAM
    cool... I will check that. The humming noise does change with movement of the LCD screen, so that makes sense. Just to clarify, I had not changed the CCFD tube; but let me check on the cable / grounding and I'll post how it turned out.

    Thx. Paras.

  4. #4

    chscag's Avatar
    Member Since
    Jan 23, 2008
    Location
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    Specs:
    Late 2013 27" iMac, iPad 3, iPhone 6s+, iPhone 6+, 3 iPods, El Capitan
    cool... I will check that. The humming noise does change with movement of the LCD screen, so that makes sense. Just to clarify, I had not changed the CCFD tube; but let me check on the cable / grounding and I'll post how it turned out.
    OK, I just re-read the original post and you're correct. You only changed out the inverter board. After checking out the cables, if they're alright, you may in fact have a noisy CCFD. Changing out just the CCFD is a difficult job. Apple recommends a new display instead.

  5. #5


    Member Since
    Jan 24, 2011
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    81
    Specs:
    Late 2010 Mac Pro 5,1 with 3.33Ghz 6-core, and 16GB RAM
    OK... I understand, but I might try to replace the CCFD anyway... any advice?

    But the humming has gotten better, so the cables may be the issue. Let me see how it's working for a bit.

    thx.

  6. #6

    chscag's Avatar
    Member Since
    Jan 23, 2008
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    Late 2013 27" iMac, iPad 3, iPhone 6s+, iPhone 6+, 3 iPods, El Capitan
    Quote Originally Posted by parasbuy View Post
    OK... I understand, but I might try to replace the CCFD anyway... any advice?

    But the humming has gotten better, so the cables may be the issue. Let me see how it's working for a bit.

    thx.
    The best take apart instructions are on iFixit: The free repair manual. However, as I stated before, changing out a CCFD is a difficult task involving getting inside the display area. Keep trying to re-orient the cables to see if it makes a difference.

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