Very strange USB port problem

Discussion in 'iMac' started by portreathbeach, Feb 24, 2015.

  1. portreathbeach macrumors member

    Feb 19, 2011
    I have been a Mac user for many years and have come accross a strange problem with a USB device.

    I do a lot of PIC microprocessor programming and have been using a PICKit3 (USB programmer) for a few years now. A week ago, the PICKit3 stopped working or being detected by the computer. I bought a new one and plugged it in. MPLabX, the programming software 'sees' the programmer, but when I go to actually use it, the software eventually says that it cannot connect to the programmer.

    Now, here's the strange bit. If I plug the programmer into one of the USB ports on my wired keyboard, it works fine. I thought tat it may have been a problem with one of the USB ports in the rear of the machine, so I removed the keyboard and plugged the programmer into the port it was in, still does not work.

    I then re-connected the keyboard and put the programmer into one of it's USB ports and again, it works. What can be causing this?

    Any help would be great :)
  2. dyt1983, Feb 24, 2015
    Last edited: Jun 1, 2015

    dyt1983 macrumors 65816

    May 6, 2014
    edit: To remove personally identifying information not relevant to the thread.
  3. portreathbeach thread starter macrumors member

    Feb 19, 2011
    I've been using it on this Mac for the last 2 or 3 years.

    Ok. After a chat with Apple, I have got it to work.

    If I have my USB card reader and the PICKit3 in the back, the PICKit3 doesn't work. If I have one of them plugged into the wired keyboard USB port on the side and one plugged in the back, they both work!

    They both have been working fine together for the last couple of years in the back, so I don't really know why they would stop working now.
  4. portreathbeach thread starter macrumors member

    Feb 19, 2011
    Ok. It's only working again if I use the keyboard USB!!!

    What is going on?
  5. iMac5,1User macrumors newbie

    Feb 23, 2015
    New Jersey
    I recommend dusting the USB ports or opening up the mac and see if one of the cables is broken or unplugged:apple::apple:
  6. portreathbeach thread starter macrumors member

    Feb 19, 2011
    The strange thing is, I have tried every port on the back with the keyboard, an old wired mouse, flash drives and hard drives and it's only the PICKit3 which doesn't work.

    When it's plugged in, the software can see it, and knows it's there, but it won't work. I can't understand how it works when plugged into one of the USB sockets on the keyboard though!
  7. matreya macrumors 65816


    Nov 14, 2009
    A possible reason it's working in the keyboard is that the keyboard is a USB hub... have you updated System software recently?
  8. portreathbeach thread starter macrumors member

    Feb 19, 2011
    I updated to Yosemite a while back and haven't changed anything recently. It just stopped working.

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