Important Note: This is a part of the original Emergency Handbook. It has been renamed the Troubleshooting Handbook and substantially revised. Click Here to go to the current Troubleshooting Handbook.

Problems With USB Devices is part of Chapter 2: Problems With Your Computer, pp: 33-34 of the iMac Emergency Handbook.

Message appears saying the device can't operate because it needs more power than is available.

• If the device has a power cord, make sure the cord is plugged into a working electrical outlet.
• Plug the USB cable from the USB device into a USB port on your computer or another USB device that is plugged into a power outlet.
• If the device is connected to a USB hub, do the following:
• If the hub has a power cord, make sure the cord is plugged into a working electrical outlet.
• Try unplugging one or more devices from the hub.

Message appears saying a device may not provide all of its functions because it requires more power.

• If the device has a power cord, make sure the cord is plugged into a working electrical outlet.
• Plug the USB cable from the USB device into a USB port on your computer or another USB device that is plugged into a power outlet.
• If the USB device is connected to a USB hub, try unplugging one or more devices from the hub.

• If the device has a power cord, make sure the cord is plugged into a working electrical outlet.
• Plug the USB cable from the USB device into another USB port on your computer or another USB device that supplies power (such as a hub).
• If the device is connected to a USB hub, try unplugging one or more devices from the hub.

The device isn't working, but no message appears.

• Make sure the USB connectors are plugged in properly.
• If the device has a power cord, make sure the cord is plugged into a working electrical outlet and the device is turned on.
• Some USB devices, such as printers, need to warm up for a few minutes after you turn them on. For more information, see the documentation that came with your device.
• Make sure you've installed the necessary software to use the device. USB devices use software called "drivers" that allow your computer to check the device when it's connected to make sure it gets enough power and speed. Some software drivers are already available on your computer in the Mac OS. However, with some devices, you may need to install the software drivers. For more information, see the documentation that came with your USB device.
• If you suspect a mouse problem, clean your Apple USB mouse as described in the online documentation that came with your computer. Then, plug the mouse into an open USB port on your computer. If the mouse works, then you may have a problem with the keyboard. If the mouse doesn't work, borrow an Apple USB mouse from another computer and connect it to yours. If that solves the problem, you may need to repair your mouse. Consult an Apple-authorized service provider.
• If you suspect a keyboard problem, borrow an Apple USB keyboard from another computer and connect it to yours. If that solves the problem, you may need to repair your keyboard. Consult an Apple-authorized service provider.
• Make sure the cables on your device are not damaged or frayed. If so, contact the manufacturer of the device or see the documentation that came with the device.

• To find out more about USB and your computer, see the online documentation that came with your computer.
• To find out more about your USB device, see the documentation that came with the device.

To view the other sections of Chapter 2: Problems Using Your Computer, click on any of the links below:

• Article 43039: Problems with Applications, Documents and Memory
• Article 43040: Problems with Hard Disks, CDs, and Other Storage Media
• Article 43042: Problems Printing
• Article 43043: Performance and Other Problems
• Article 43044: Problems with Networks and File Sharing
• Article 43045: Problems with Sound and Video