External hard drive keeps disconnecting and then reconnecting

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External hard drive keeps disconnecting and then reconnecting

External hard drive on Time Machine, running via USB keeps disconnecting. Get the pop us that the drive wasn't disconnected properly. This Mac is brand new as is the hard drive. It is a Seagate 1T Free Agent.

After a minute or two it reconnects. I've run Seagate diagnostics and it says the drive is fine.

Any suggestions?

Mac I21

Posted on Dec 1, 2010 7:19 PM

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Answer 1

Dec 1, 2010 11:50 PM in response to foxdid

Usually when I see that it is a power problem on the USB bus. If I have my iphone, backup disk, and scanner all plugged in they're fine. If I then plug in my ipad, the entire thing will hiccup. All devices disappear and then reappear.

You can check this by running Console.app and selecting "All Messages" in the sidebar of logs. You should see a bunch of errors fly by about the USB having problems and various apps reacting to the reset.

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Answer 2

Dec 2, 2010 12:19 AM in response to foxdid

As zenspider said, this is likely a power issue. Try plugging the drive directly into the Mac and unplugging all other USB devices. Additionally, if the drive has an option for an external power supply, then use it.

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Answer 3

foxdid Author

Level 1

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Dec 3, 2010 7:41 PM in response to Topher Kessler

The external drive is using a separate power supply. I have my keyboard and external hard drive plugged in to the USB's and then a USB hub. The Hub works fine as does the keyboard. Never a blip. The problem doesn't seem to be particular about when it happens. This is making me crazy. I have to click okay when the warning pops up before I can do anything else.

Thanks for both responses I've received. Any further suggestions?

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Answer 4

Pondini

Level 8

38,863 points

Dec 3, 2010 10:09 PM in response to foxdid

See #A1 in [Time Machine - Troubleshooting|http://web.me.com/pondini/Time_Machine/Troubleshooting.html] (or use the link in *User Tips* at the top of this forum), for a handy widget that will display the backup messages from your logs.

See what that shows; there may be a problem with the backup, which results in TM ejecting the drive. If so, the disconnect may be a symptom, not a cause. If so, see #C2 there. If not, or if you're not sure, copy and post them here.

Also, to rule out other USB problems, disconnect everything but keyboard and mouse; connect the drive directly to your Mac (no hub).

Make sure all connections are snug and secure.

Try other ports, cables, and combinations of the two (a plug that works fine in one port may not make good contact in another one, and throw intermittent errors).

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