Odd Mac feeling - ground loop?

krispiekrispie
Posted:
in Genius Bar edited January 2014
Sometimes my Mac Pro feels odd - is this related to 'ground loops' that I'm familiar with in the audio world?



If I touch my MacBook Pro, it feels normal.



If I touch my Mac Pro, it feels normal.



If I touch my Mac Pro with my left hand while touching my MacBook Pro with my right hand it feels normal.



EXCEPT when I move either hand. Then, it's as if the surface were rough. Like there's some vibration when moving fingers that's not obvious when they're still.



On each machine, there's no such feeling unless I'm touching the other.

Comments

  • Reply 1 of 4
    dac0nvudac0nvu Posts: 175member
    Quote:
    Originally Posted by krispie


    Sometimes my Mac Pro feels odd - is this related to 'ground loops' that I'm familiar with in the audio world?



    If I touch my MacBook Pro, it feels normal.



    If I touch my Mac Pro, it feels normal.



    If I touch my Mac Pro with my left hand while touching my MacBook Pro with my right hand it feels normal.



    EXCEPT when I move either hand. Then, it's as if the surface were rough. Like there's some vibration when moving fingers that's not obvious when they're still.



    On each machine, there's no such feeling unless I'm touching the other.



    I only have a MacBook Pro and I feel the same thing when I run my fingers over the cover. I used to think it was a (very slight) vibration, but now I just think it is the surface...not rough, but like you say, like a vibration. Weird 8)
  • Reply 2 of 4
    marc5marc5 Posts: 8member
    it ony happens when its plugged right? run the MBP on batteries and its fine?

    Its to do with the grounding on the machine, what you need to do is use the extension cord that came with your brick, that cord has a third ground pin, and that will take away the funny feeling you're getting.
  • Reply 3 of 4
    chrisdamacmanchrisdamacman Posts: 180member
    Do american plugs not all have 3 pins i.e. the third to ground the machine in case of short circuit. All britsh plugs for high power appliances have one and by law to be fused.



    So I'm not sure if using the extention cord would help most probably slight vibration. So i would say just stop touching up your computer if it was a women it would slap you
  • Reply 4 of 4
    splinemodelsplinemodel Posts: 7,311member
    It could be a ground loop, particularly if you are running the MBP on battery, or if your earth ground is not connected within the electrical outlet. Quite often it is not, and the AC-DC converters inside the computers are isolated, so they produce their own ground.



    You may want to inspect your wiring.
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