external hard drive not even seen

Discussion in 'iMac' started by chips7400, Aug 13, 2010.

  1. chips7400 macrumors newbie

    Aug 13, 2010
    Hi, I am new to apple computers and have been spending the last week transferring files across. My Toshiba external hard drive is now empty though probably still formatted for windows. If I plug it into the USB port of my imac it is not even recognised and does not show up when I run disc utilities. How can I ever get this drive to work. It does seem that no one is able to get an answer to this and I am beginning to regret the move. Any suggestions.. Thanks
  2. Hellhammer Moderator


    Staff Member

    Dec 10, 2008
    Is it recognized on another computer? If it isn't, there is something wrong with the drive
  3. chips7400 thread starter macrumors newbie

    Aug 13, 2010
    external hard rive not seen

    Hi Thanks for the reply but it was recognised by my old pc and Iwas still able to copy files to it and delete them. On connecting to my imac it is not even seen. I have anew imac 21.5 inch 500 gb 3.02 with 4 gb of ram running mac OS X 10.6.4
  4. spacebased macrumors newbie

    Apr 11, 2010
    Yankee in the Deep South
    Same problem - stop & start resolved once

    This happens with one of my external drives (a seagate). I don't know why but I have to fiddle with stops and starts to get it recognized, i.e. stop the mac, unplug the drive from the usb, start up the mac and then plug it in and it's recognized. But if I stop the mac for any reason I get to do it all over again. The WD I use for Time Machine never has this problem so i suspect some type of formatting tweak is at fault.
  5. drambuie macrumors 6502a

    Feb 16, 2010
    Is it a drive that has its own power supply, or does it get power from the USB port? Also, does the drive's activity light indicate it is functioning when it power-on initializes, or is plugged into the iMac's USB port? I assume you did try it on all the iMac's USB ports.
  6. Greenjeens macrumors regular

    Aug 25, 2005
    I have had about every kind of problem and disaster you can imagine running lots of external drives and dock stations with my G4 and now an Imac Cor2Duo.

    SOmetimes NOthing can be seen on my Imac I unplugged everything INCLUDING THE POWER CORD and let it sit for about 15 minutes or so and all the external hard drives showed right up, once again. Whew!

    In the case of using a couple of HD docks, all I had to do was to finally remove any jumpers on the rear of the hard drives and poof! suddenly they were showing up on the desktop.

    I did have an unpleasant occurrence after purchasing 3 refurbished OWC Elite PRO dual HD Aluminum housings and stocking them with 2 new WD TB black drives. 2 of them just stopped showing up on my desktop about a month after purchase and never were seen again, except the one I sent back after "repair" stayed connected for a day or so. The third Elite pro HD box has been running perfectly since day one for a year and a half. Saving my extensive itunes library from oblivion!

    Needless to say the discs were in a simple RAID form to appear as one 2 TB single drive and once the drive enclosure failed so did the data accessibility:-(
  7. chips7400 thread starter macrumors newbie

    Aug 13, 2010
    The drive has its own power supply and the blue light is on to show it works. I have not yet tried it in every USB port. I have another drive that has no internal power and that has been picked up with no problems. Will reply further when I have tried all USB ports. TA
    Does not work on any of the ports but my WD drive is picked up immediately. Iwas hoping to use my empty toshiba drive as my TIME MACHINE drive.
  8. drambuie macrumors 6502a

    Feb 16, 2010
    It looks like the problem is with the Toshiba drive's USB interface. The signal levels could be marginal, and the iMac doesn't have much tolerance for low levels. The fact that it works on other PCs indicates that the Toshiba HD itself is good. If it has good capacity, and is worth using, you could remove the drive and buy another enclosure. Third party USB drive enclosures are inexpensive. For a bit more, you can get enclosures that also have eSATA and Firewire 400/800.

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