View Full Version : An odd issue

18th October 2007, 09:25 AM
Hi All,

A couple of months ago I poured coffee into the moniter of my Powerbook (1.67Ghz G4) powerbook while hung over and killed it. So I set it up as a desktop computer replacing my old crappy 800Mhz iMac.

About 2 weeks ago something strange suddenly happened to the USB ports. Only one port will work at any one time. Originally I thought one of the 2 ports simply died. But the weird thing is when I reboot the computer the broken port switches side.

So at the moment I have my HHD, printer mouse and keyboard all running through a 4 port hub which works but is annoying and I have to swap ports every time I turn on the computer.

Any thoughts as to what in the world is happening?

18th October 2007, 09:40 AM
Do you have a device that doesn't have external power in one ofr the usb ports at anytime?

This can lead to the usb port simply shutting down until a restart.

18th October 2007, 10:48 AM
The coffee might have corroded more than your display in that case.

18th October 2007, 11:06 AM
I'm with Curra, methinks your advanced experiment in fluid dynamics is having far-reaching consequences, and the resulting spread of corrosion is slowly but surely eating away at the extremities of your plagued PowerBook like a cancer.

As to your USB problem, what I strongly suspect is this: When you power on the computer, you are also powering on the USB devices (the hub, keyboard and mouse specifically) -- alas, that original demand for current temporarily overwhelms your USB port's ability to provide power, so the USB chip does what it was designed to, and shut that port down.

The solution is to buy a powered USB hub, something that can provide a proper 500 mA per device; a 4-port powered hub will come with a 2.5A power supply, 500 mA per device plus 500 mA for the hub itself.


18th October 2007, 11:07 AM
I don't know if it's the same with USB, but FireWire ports can shut down, and resusitated by resetting the NVRAM.

Worth a try?

1. Start up into Open Firmware by pressing and holding the Command-Option-O-F key combination during startup.

2. At the Open Firmware prompt, type: reset-nvram

3. Press Return.

4. When prompted for your password, enter it and press the Return key. It responds OK.

5. At the Open Firmware prompt, type: reset-all

6. Press Return.

18th October 2007, 11:33 AM
I'm using a powered hub...

I'll try the NVRAM idea and see if that works. Might try booting up without any usb devices attached as see what happens.

Hopefully the cancer theory isn't true. It's been 2 months and this has only happened in the last 2 weeks so hopefully this isn't the case (fingers crossed).

Edit: Ok I played around with it without doing the NVRAM thing. It seems it has something to do with the hub. I rebooted with the keyboard and mouse plugged in but not the hub and the same port works fine. Reboot with the hub and the port dies. So for now I guess I'll simply just only plug in the hub (using the printer or the HHD) when I need too.

Very odd though, both these devices use power (and the printer isn't even turned on) and the hub is also powered and plugged in. I wouldn't think over powering it is an issue but it seems it is.