"usb device drawing too much power" error message pops up occasionally

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Level 1

4 points

"usb device drawing too much power" error message pops up occasionally

The error message goes on to say that the port it is connected to will be deactivated. I already lost power in my cinema screen's usb ports, so this message makes me really nervous (I only have 2 usb ports in the back of the computer). It seems to occur after several hours of computer usage, and nothing else has happened yet. The only usb devices I have connected are an inkjet printer and a 9x12 Wacom tablet. Anybody have an idea what's going on, and if there's anything I can do to prevent a failure?

G4 MDD 867, G4 Q'slvr 733 & iBook G3 900, Mac OS X (10.4.11)

Posted on Jun 18, 2010 5:44 PM

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Answer 1

Mike in LA Author

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4 points

Jun 18, 2010 5:50 PM in response to Mike in LA

My first post is not completely accurate: I also have the keyboard plugged into the back of the computer (since I lost the monitor ports) and the mouse and printer are plugged into the 2 keyboard ports.

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Answer 2

BDAqua

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Jun 18, 2010 6:02 PM in response to Mike in LA

It sounds like one of those devices is going bad or has a flaky power supply, which ones have regular USB A type fittings?

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Answer 3

Mike in LA Author

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Jun 18, 2010 6:13 PM in response to Mike in LA

hi: the tablet doesn't have a power supply of its own, it's powered directly from the usb port (which is why you have to use the ports on back of the computer to properly power it). I don't think that's the problem because I have two of these 9x12 tablets, and already switched one out for the other tablet, and am still getting that error message. The printer plugs directly into a power strip (no seperate power supply). I've turned the printer off and so far the error message hasn't been repeated.

What is an "A type" fitting?

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Answer 4

BDAqua

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239,213 points

Jun 18, 2010 6:37 PM in response to Mike in LA

I'd strongly consider an AC powered USB Hub or two to isolate your poor USB situation...

http://www.amazon.com/Hi-Speed-Powered-7-Port-7Ports-Adapter/dp/B001MWAS66

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Answer 5

Mike in LA Author

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Jun 18, 2010 6:45 PM in response to Mike in LA

OK I have type A (the older type) of usb I guess. I've thought about getting a hub too - sounds like a good idea.

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Answer 6

BDAqua

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239,213 points

Jun 18, 2010 7:14 PM in response to Mike in LA

Yeah, all Computers have the A type, that supplies power as well as data, I think if the other end is B type then it doesn't use power from the computer.

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Answer 7

Mike in LA Author

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Jun 18, 2010 7:18 PM in response to Mike in LA

the end of the cable going into the printer is the B type. The tablet has a fixed connection at the tablet end.

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Answer 8

BDAqua

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239,213 points

Jun 18, 2010 7:45 PM in response to Mike in LA

Yeah, but the Printer Data lines could still be bad.

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Answer 9

Jun 18, 2010 10:16 PM in response to Mike in LA

Hi, Mike -

Apple KBase article Article #TA26015 - Apple Pro Keyboard: Devices Connected indicates that you should not connect your printer to a port on the keyboard, because of the possibility of overloading the keyboard's ability to pass power via its unpowered hub.

I had an experience years back where an optical mouse connected to the keyboard was overloading the keyboard's hub. The solution for me was to connect the mouse to a different port.

In your case, you could get a self-powered USB hub and connect it to one of the two ports on the back of the Mac and then use it for both the mouse and the printer, leaving the keyboard connected to the other native USB port. Self-powered hubs connect to your power strip and provide operating power via the USB bus to other devices connected to it, thus relieving the Mac's PSU and USB circuits from the need to do that.

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Answer 10

Mike in LA Author

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4 points

Jun 18, 2010 10:17 PM in response to Mike in LA

I think you might be right about the printer. It's starting to act up, like it will skip lines in a document if I don't set the quality higher in the print settings. And I don't seem to get that error box when the printer is turned off. Time for a new printer. I'll consider my issue probably solved.

Thanks for your input.

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Answer 11

Mike in LA Author

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4 points

Jun 18, 2010 10:23 PM in response to Mike in LA

Hey Don, I didn't see your reply while I was typing my last one. Makes sense, this just started happening since I connected the printer to the keyboard hub instead of the back of the monitor. Come to think of it, if the monitor hub on the Cinema Screen isn't powered either, I wonder if that's how I lost functionality in those ports?

Thanks for the info.

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Answer 12

Jun 18, 2010 10:38 PM in response to Mike in LA

Hi, Mike -

Hubs in monitors are, in my experience, usually powered ones. I've never had one balk or complain about whatever I had plugged into it.

On the other hand, such a hub is provided as an extra or courtesy feature on a device that fundamentally has nothing to do with USB, so its design or components may not be the most robust. One might think that with the extra space available in a monitor that a hunky USB hub could be included; on the other hand, 'value engineering' requires that the minimum-cost components that meet spec should be used.

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Answer 13

Cm Tong

Level 1

9 points

Jul 1, 2010 11:48 PM in response to Don Archibald

My 2GB usb flash drive cannot be operated through the sockets of the Apple keyboard (with warning: a usb device can't draw enough power). I think it's unusual as such a drive is low-powered and I'm sure that it could be used perfectly not long ago. There must be something wrong or changed in the usb power output of the keyboard. I don't know exactly when the problem has started, but before 10.6.4 and persisted after the update.

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Answer 14

BDAqua

Level 10

239,213 points

Jul 2, 2010 12:01 AM in response to Cm Tong

Hi, but at the end of the day, nothing like an AC powered USB Hub to cure the problem! 🙂

http://www.amazon.com/Ports-Adapter-Support-Self-powered-Bus-powered/dp/B002MV7L 6Q

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Answer 15

Cm Tong

Level 1

9 points

Jul 2, 2010 9:30 AM in response to Cm Tong

Let me continue with my story. The usb drive seems to work fine with the ports behind the iMac but it's really inconvenient in doing so! At the same time, I have similar problems with my usb laser printer. Sometimes the iMac just ignores the already switched-on printer which is connected via a hub. These usb problems occur often only recently.

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