USB on my iMac not working

Discussion in 'iMac' started by jerrry, Aug 18, 2014.

  1. jerrry, Aug 18, 2014
    Last edited: Aug 18, 2014

    jerrry macrumors newbie

    Mar 27, 2011
    Hello, I have 27" (late 2012) iMac. Today I have tried to boot into Windows/bootcamp (in case to flash my smartphone). I did this normally 2-3x times per month for last one year with no problem. But today, for the first time, my iMac stuck on white boot screen. I hold Power button to turn off, wait a few seconds and turn in on again. Because I set (in OS X) to boot into Windows, iMac is now automatically booting into Windows.

    But the biggest problem is than iMac now can't recognize my wired keyboard (I bought new one 2 weeks ago). I tried to connect this keyboard to my MacBook Air (for check if is working) – and yes, it's working, so there is no program with keyboard.

    The problem is than my iMac is not detecting keyboard in anyone of 4 USB ports on the back side. So I can't do anything, because iMac don't recognize the Option key holding while booting (for change to boot back to OS X). Do you have any idea where can be a problem and how I can fix it?
  2. maflynn Moderator


    Staff Member

    May 3, 2009
    Did you plug in any other USB device to see of those get recognized?

    Its probably the logic board, i.e., some circuitry on the board that controls the USB.

    Call apple and/or take it in, because there's not much you can do at this stage, other then use a wireless keyboard.
  3. jerrry, Aug 18, 2014
    Last edited: Aug 18, 2014

    jerrry thread starter macrumors newbie

    Mar 27, 2011
    Thank you for reply. Yes, if I plug any USB device (smartphone via USB cable, USB Flash disk, USB external drive) - everything is working fine. But when I connect keyboard to iMac - it's not working. And when I connect this same keyboard to my MacBook - everything works perfect. And what is really strange, than iMac cant recognize this keyboard on booting screen. Btw, I don't have a wireless keyboard, I am using only this wired keyboard.

    edit: wohooo, I have no idea how this happens, but after few more restarts keyboard again working, ufff :)
  4. jerrry thread starter macrumors newbie

    Mar 27, 2011
    Okay, after few days the problem is back. I temporary solved it by USB hub with 4 ports, but…

    …when I connect my original Apple wired keyboard to anyone of 4 ports on the back of my iMac – keyboard isn't working.

    …when I connect my Apple wired keyboard to USB hub, which is connected to anyone of 4 USB ports on the back of my iMackeyboard is working.

    What the hell is this? :-D Can someone tell me how can be this caused? :) Because I am little bit confused right now.
  5. WilliamG macrumors G3

    Mar 29, 2008
    Sounds like something is wrong with the keyboard that is causing the iMac to not like it being connected directly (despite it working with other computers). Can you get another Apple wired keyboard and try it?

    To me it seems likely the keyboard is broken in some way, since when it wasn't working in your iMac - all other devices were. Best way to troubleshoot is to get another keyboard, and when the issue happens again on the original keyboard, swap in the replacement and see if that works immediately.

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