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Thread: USB power

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    We have a Maxtor OneTouch Mini III (80Gb), which we use for server backup using Acronis.

    The Maxtor has a strange USB lead with 2 heads, 1 for power and 1 for data.

    It has been used (up to now) on a powered USB Hub, with great success. Being a Belkin hub as well as being very expensive it has also given up the ghost and has been given a decent funeral.

    The Maxtor was then plugged directly into the server and Acronis is now complaining that the media is bad or non-existant. The only thing I can think of is that the USB port(s) on the computer are not giving out enough wiggley amps.

    Does anyone know how much power the USB ports actually give out?

    David

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    [quote name='dd_uk' post='769246' date='05-Apr-2009 07:46']... Being a Belkin hub as well as being very expensive it has also given up the ghost and has been given a decent funeral.[/quote]
    I don't remember the "technicals" to answer your power question but I can tell you that I had the same problem several years ago and there may be a post somewhere here in The Lounge. MY experience was that the USB ports do NOT supply enough power to drive a hard drive and I too ended up buying a powered hub. Have not had a problem ever since, although my two current USB drives have their own AC power, so it could be a moot point. I'd recommend getting another powered hub but that doesn't come with technical expertise.

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    Super Moderator BATcher's Avatar
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    [quote name='dd_uk' post='769246' date='05-Apr-2009 12:46'][/quote]
    There's something about USB power draw limitations here.
    BATcher

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    Do you have BOTH of the plugs plugged in?
    I have never had to use the extra power as I have always been plugged into the Computer ports with NO external hub.

    Now running HP Pavilion a6528p, with Win7 64 Bit OS.

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    Uranium Lounger viking33's Avatar
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    [quote name='dd_uk' post='769246' date='05-Apr-2009 07:46']Does anyone know how much power the USB ports actually give out?

    David[/quote]

    Most USB ports are limited to about one half amp or 500 milli amps. Not enough to properly power a hard drive with only the USB power.
    An external power adapter is used or I wired up a cable with male and female 4 pin "molex" connectors to plug directly into one of the PSU cables inside the box.
    BOB
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    Super Moderator jscher2000's Avatar
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    [quote name='viking33' post='769291' date='05-Apr-2009 13:50']Most USB ports are limited to about one half amp or 500 milli amps. Not enough to properly power a hard drive with only the USB power.[/quote]
    There is a class of lightweight portable (often pocketable) hard drives that run fine with only power from a USB port, sometimes using a second port for supplemental power.

    Since it worked for the poster before, I would be more suspicious of the USB ports in the server. However, I don't know of any way to test them for proper output.

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    Super Moderator BATcher's Avatar
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    [quote name='jscher2000' post='770214' date='12-Apr-2009 21:12']There is a class of lightweight portable (often pocketable) hard drives that run fine with only power from a USB port, sometimes using a second port for supplemental power.[/quote]
    This uses-two-USB-ports requirement also happens for 'some' external USB CD/DVD drives; in preference I will be getting one which is separately powered.
    BATcher

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    I have a couple of these and I like them when I am on the road, but at home, the ones we use have their own power supply. I would NOT rely on the USB power for a long term use.

    Now running HP Pavilion a6528p, with Win7 64 Bit OS.

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    You can check this out with a few searches, but to the best of my understanding, the second lead is for USB 1 (1.1) only. And to my own horror and not-so-funny hilarity, I have just read your post with an old computer beside me that has only USB 1.1 slots and which I am backing it up to an unpowered external drive while using only the main lead of the pair.

    Yes, at this very moment. Since I'm obviously in need of information (and am using a different computer), I had better do the searches myself, and I will see if I can come up with some useful links for both of us.

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