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Repair guides and disassembly information for Apple's Macintosh personal computers.

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Reactivating my USB hubs

Hello and help…

I’ve a Mac Book which I lent to a friend for the weekend and they rather stupidly tried to test an external CD player they’d bought second hand via the laptops USB ports. Apparently the laptop powered down and now everytime I power up the laptop this message appears.

“USB over current notice. A USB device is currently drawing too much power. The Hub it is attached to will be deactivated”.

The laptop powers up ok and all other applications seem to be ok. There’s nothing connected to the USB ports but as per the message, I can’t use anything via it, like web dongle, memory stick etc.

Any idea’s as to how to reactivate the USB ports safely?

Thanks muchly

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We need to know your exact machine, please give us the last three figures of your serial number. Try each of the following steps in this order before you reset the SMC. Test the issue after completing each troubleshooting step to determine if the issue still occurs.

Press Command + Option + Escape to force quit any application that is not responding.

Put your Mac to sleep by choosing the Apple () menu from the upper-left menu bar and then choosing Sleep. Wake the computer after it has gone to sleep.

Restart your Mac by by choosing the Apple () menu from the upper-left menu bar and then choosing Restart.

Shut down your Mac by by choosing the Apple () menu from the upper-left menu bar and then choosing Shut Down.

If your Mac appears to be running normally but isn't responding, force the computer to shut down by pressing and holding the power button for 10 seconds. Note: You will lose any unsaved work in any open applications.

For Mac portables experiencing issues related to the MagSafe power adapter and/or battery, try:

Unplug the MagSafe power adapter from the Mac and the wall power socket for several seconds.

Shutdown the Mac. Physically remove and re-insert the battery (if it's removable) and startup the Mac.

If the issue is still not resolved after following the troubleshooting items above, an SMC reset may be necessary.

Reset your SMC system management controller

Shut down the computer.

Disconnect the MagSafe power adapter from the computer, if it's connected.

Remove the battery.

Press and hold the power button for 5 seconds.

Release the power button.

Reconnect the battery and MagSafe power adapter.

Press the power button to turn on the computer.

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