USB Overload Error

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Level 1

130 points

USB Overload Error

I'm trying to help a friend out with a problem. His eMac fairly frequently shuts down the USB bus that his keyboard and mouse is connected to. The error indicates that the stuff connected to the port is using too much power. It happens with the K&M plugged into either port. The printer doesn't seem to cause the same error. Yet, swapping a different keyboard and mouse doesn't seem to make the problem go away.

It almost sounds to me like an over-sensitive protection circuit in the USB hardware. Is this something that eMac's have a track record of? Is the USB hardware part of the motherboard in these machines? Anything known about fixes?

From the System Profile:

Host Controller Location: Built In USB
Host Controller Driver: AppleUSBOHCI
PCI Device ID: 0x003f
PCI Revision ID: 0x0000
PCI Vendor ID: 0x106b
Bus Number: 0x1a

Any experience, knowledge, wisdom will be appreciated.

null

1.25 GHz MDD, single processor, no Firewire 800, Mac OS X (10.5.6), Also a MacBook Pro, 2.4 GHz Core 2 Duo, 4 Gb

Posted on Jul 15, 2009 6:19 AM

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Answer 1

Best reply

Allan Jones

Level 9

68,600 points

Jul 15, 2009 8:30 AM in response to Roger Diggle

Hi Roger,

It would help to know the exact specs of the eMac. Early ones have only USB 1.1; later ones had USB 2.0. Might make a difference.

If anything is on a USB hub, the hub should be a self-powered version (has its own power cord). Bus-powered hubs that get power from the computer's USB bus often cannot deliver all that's needed to the various devices

USB ports on the keyboard are low-power and seldom can power anything more demanding than a mouse. None of our Macs with keyboard USB ports will mount a flash drive plugged into the keyboard, yet will when it's plugged into a logic board port.

Is the USB hardware part of the motherboard in these machines?

Yes. And no PCI slots to let you add ports. That's why a self-powered USB hub in your friend.

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Answer 2

Roger Diggle Author

Level 1

130 points

Jul 16, 2009 4:04 AM in response to Allan Jones

Thanks for your reply.
And for reminding that I forgot to paste the model info:

Model Name: eMac
Model Identifier: PowerMac6,4
Processor Name: PowerPC G4 (1.5)
Total Number Of Cores: 1
Processor Speed: 1.42 GHz
L2 Cache (per CPU): 512 KB
Memory: 512 MB
Bus Speed: 167 MHz
Boot ROM Version: 4.9.2f1
Serial Number (system): RM61511 ** <Edited by Host>

There's no USB hub in this system, other than the one in the Mac keyboard. I can imagine that a powered hub might take the tiny load of the keyboard and mouse off of the Mac's USB ports. However tiny that load is, it does seem to matter.

Message was edited by: Roger Diggle

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