USB Strange behaviour

Discussion in 'MacBook Pro' started by isianto, May 4, 2007.

  1. isianto macrumors regular

    Joined:
    Feb 12, 2007
    Location:
    Indonesia
    #1
    Dear all, I have a macbook pro, and I use external usb dvd-rw. It works great on my toshiba portege, anyway everytime I use the same drive to my macbook pro, either on windows (bootcamp) or on macosx, I always have warning that usb doesn't have enough power to use this drive (even though I use it with my power adapter plugged to my macbook). What is wrong? Other than using external power supply for my external dvd, do you guys have a pointer I could follow?
    Thanks'
     
  2. szsiddiq macrumors 6502

    szsiddiq

    Joined:
    Dec 21, 2005
    #2
    Does it happen on all USB ports? Give it a shot on another MacBook Pro (apple store or a friends) and see what happens. If it does it again, it's most likely a driver bug. If it doesn't it most likely a hardware issue.

    Does the drive have its own power source? does the same issue happen with other devices? (iPod, etc.?)
     
  3. PDE macrumors 68020

    Joined:
    Nov 16, 2005
    #3


    I've found that to happen quite frequently with my macbook. Not with a drive, but with any powered USB device.Iffy and not reliable. Sometimes one port doesn't work, at others times the other one doesn't work properly. This was the case with all macbooks I've had. I would say up time for both ports is about 96%, with the 4% downtime distributed rather evenly between the ports.. Anybody else?
     
  4. deadpixels macrumors 6502a

    deadpixels

    Joined:
    Oct 30, 2006
    #4
    is it plugged through a hub? if yes, try to plug it directly.
     
  5. tilman macrumors regular

    Joined:
    Feb 28, 2006
    #5
    I would suggest the opposite :) I have never seen an external bus-powered burner. Apparently, the drive wants to use more power than the USB ports on your MacBook Pro can supply. I don't know the specs for the MacBook Pro, but it is quite common for laptops to have only limited power available on the USB ports. To work around that, use an external power supply for your drive, or plug it into a powered USB hub. Then the power is drawn from the hub's power supply, and not the MacBook Pro.
     
  6. isianto thread starter macrumors regular

    Joined:
    Feb 12, 2007
    Location:
    Indonesia
    #6
    It has a jack for external power, but I didn't get the adaptor. It directly plug into usb on my macbook pro. But the question is the apple usb provide less power than other pc notebook usb? since I use the same drive with my compaq and my toshiba.
    Thanks for the reply
     
  7. mkrishnan Moderator emeritus

    mkrishnan

    Joined:
    Jan 9, 2004
    Location:
    Grand Rapids, MI, USA
    #7
    Yeah, it seems like notebooks from some of the PC majors are more generous with how much power they provide on the USB bus. This comes up occasionally with bus-powered USB on Macs -- there have been numerous discussions about this in the past on the Powerbook and iBook as well.

    I'm not really certain whether this is an issue of walking specs in the PC world (e.g. PC manufacturers accommodating drive assemblers who ignore the USB power specs) or if it's an issue where the Apple products should legitimately have more USB bus power. But either way, they don't. Meaning that an external power supply or a powered hub are your choices.
     

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