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July 17, 2006, 6:13 pm
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I am posting this here as nearly all laptop users will probably have
the need for smaller unpowered, USB hubs.
I have two, both of which symptomatically have died in same
One is a Tevion 4 port USB 2.0 and the other a more portable Belkin
mini mobile unit.
I have never had to power either for the lightweight usage of USB
mice/Thumbdrives etc, but neither now seem to draw enough power from
either my IBM Thinkpad T23, or a T42 or desktop machine. I
disconnected all other USB devices so as not to reduce the port
All my USB devices seem to work OK when plugged directly into the USB
ports on the PCs mentioned or through a cardbus PC - USB2 card.
Any comments welcome.
Re: USB hub deaths...
Whilst the hubs are plugged in, check devivce manager for any unknown
devices or devices with yellow exclamation marks over them (windows key +
Pause Key; select device manager). Uninstall these (right click and select
uninstall). Unplug, pause and plug in again and see if they reinstall. If
they don't, they may be genuinely knackered (though why two should have
failed is not clear at this point)
The USB spec requires that removing other devices should not make more power
available to any individual port (Ony 100 mA can be available from each port
on a bus powered hub). Check the power available to the hubs from the root
port (tab in device manager on the root ports). If it is showing as 100 mA,
then the hubs will not enumerate. Again try ininstalling and reinstalling.
500 mA must be available before a bus powered hub will enumerate.
If this does not solve the problem, USB hubs are cheap enough that it is not
worth spending excessive amounts of time on this.
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