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Recover apparently dead USB ports Desktop Macs
The front USB port of my dual 2.0 gHz G5 desktop seemed to go dead. Flash drives would blink once and not mount. System profiler would show nothing in the port. A discussion on an Apple hardware forum had the solution: shut down the desktop and unplug the power cord for 30 minutes. Restart with nothing connected, then connect each USB component. I tried it and I found all the ports working again!

[kirkmc adds: You never know... I guess this has something to do with letting the capacitors somewhere inside the Mac lose their power...]
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Recover apparently dead USB ports
Authored by: mclbruce on Nov 03, '06 07:50:53AM

Pulling the PRAM battery will sometimes help with things like this. Remove the PRAM battery and then let the computer sit, with no power cord or battery attached, for 20 minutes or more.



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Recover apparently dead USB ports
Authored by: magir on Nov 03, '06 08:06:55AM

I can confirm that sometimes switching of the machine and waiting a few minutes indeed reactivates broken USB ports. Happened to me on a PowerBook G4.



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Recover apparently dead USB ports
Authored by: michaelj on Nov 03, '06 08:43:08AM

I've seen this documented elsewhere and had to use this trick to recover the apparently dead firewire ports on my mdd g4. It worked beautifully and the ports have been working great ever since.



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Recover apparently dead USB ports
Authored by: jmacak on Nov 03, '06 09:53:02AM
You never know... I guess this has something to do with letting the capacitors somewhere inside the Mac lose their power...

Actually, the described procedure results in resetting the SMU (System Management Unit) of a PowerMac G5. See this Apple technical note:

"How to reset the SMU..."

The article states that:
Resetting the SMU can resolve some computer issues such as not starting up, not displaying video, sleep issues, fan noise issues, and so on.

Cheers,

Jim M.
Apple Certified Help Desk Specialiast, Milwaukee, WI
YourMacDoc Macintosh Help and Consulting Services
YourMacDoc.com


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Recover apparently dead USB ports
Authored by: jasper9890 on Nov 04, '06 11:46:58AM

Yup - i had this problem on my powerbook g4. First the port on the right, then weeks later the other. Spent 5 minutes on the phone with tech support, AFTER clearing out company data from the hdd thinking i had to send it in for a new logic board or something. All better :)



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Recover apparently dead USB ports
Authored by: swisswuff on Nov 05, '06 02:40:36AM

I had the problem of "dead" USB mouse particularly with thin cables and dual CRT monitor setups (Mac, Windows or Linux), and I have this problem still occasionally on any OS (Mac, Windows or Linux).

It does not occur on the PS2 connection for some PC mice, and it rarely - but also - happens on USB keyboard connections.

The only OS where I know a real fix - that can be applied in software, on the fly, and right there - is Ubuntu Linux running on my laptop (ASUS A6T). Since it may be possible to apply a similar fix to Mac OS X, I thought it could be interesting in this context. Typically, my external keyboard and the external mouse stop working after a few minutes on my PC running Ubuntu.

However, this is recognized as a software problem, and the solution is a software solution. The commands are as follows and have to be issued as root:

modprobe -r ohci_hcd

modprobe ohci_hcd no_handshake=1

After keying in these two commands, the USB immediately turns back on, and it remains unfreezed until the end of that session (until the machine is turned off).

I guess there must be a way to do something similar on Mac OS X or Windows?



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Recover apparently dead USB ports
Authored by: Zeitkind on Nov 14, '06 01:46:25AM

For old systems with ADB, there was a little tool from Apple to reset the bus. Those utilities often come with developer stuff and SDKs, so it might worth looking into that direction. A simple modprobing the kernel modules won't work on PPC hardware I guess, but I never tried it.



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Recover apparently dead USB ports
Authored by: jeremiahblatz on Nov 05, '06 10:56:07AM

This worked for my MacBook Pro and its dead FireWire port. System Profiler said I had a FireWire bus, but nothing happened when I plugged in a FireWire device. Shutdown, unplugged, and removed the battery for 30 minutes, and my FireWire port started working again! Yay!



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Recover apparently dead USB ports
Authored by: wsdr on Nov 05, '06 02:11:47PM

One thing about this, you should also turn off/unplug each peripheral as well. What's good for the goose....

I've had several experiences with USB devices that would just stop working, and seemingly no amount of rebooting, etc., would do the trick. Most recently, we had an HP scanner just quit. The user unplugged the scanner, USB hub, and other peripherals. She turned off the computer, and all of the peripherals but one, an Epson printer. The printer sat on a shelf above, and she just didn't think about it because it was seldom used-- and was in fact, switched off. But even after all that, the scanner wouldn't work-- not until I unplugged the power from the Epson, anyway. Once I did that, it all worked perfectly.

So, unplug from USB AND Power all peripherals just to be sure.



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