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Apple Wired Keyboard USB port power

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I have an Apple Wired Keyboard with the USB ports. Problem is that they don't give a lot of power to the connected devices although the USB ports on my Hack do have the ability to power everything. For Windows7 there is a fix:




Is there a way to do the same in OSX by editing some plist file or something?

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I have that problem, too.

I read on the web that certain macs have 1000mA on usb ports, so they say you need to change wiring usb ports on boards.

When I see my system information ,apple keyboard require 300mA though 500mA is available.

I guess 100mA per each ports and 100mA for keyboard itself. so only 100mA device could work.

I hope somebody find solution for this through software method.

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I checked the ioregistry and I found there's difference in usbhub entry between cinema display and apple keyboard .

There's entries for 'extra power for ports' and 'extra power request' in keyboard hub.

Extra power for ports want 400mA and extra power request want 600mA.

So I guess it means that mac has 1100mA for usb ports.

But ioregistry of cinema display doesn't have those entries and hub supports 500mA and I can charge my phone.

If you can remove those entries in keyboard hub config, then maybe at least one port would work.

Maybe experts in dsdt could do that.



There's AppleUSBMergeNub.kext in iOUSBFamily.kext's plugin folder.

I think there's information that you need to change in info.plist of that kext.


I guess that display has its own power supply for usb ports.

I don't think it's possible to fix this problem with modifying info.plist.

Edited by kdtt

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Thanks for delving into this!


I have no idea how to edit this in a DSDT though.

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