Dell Latitude USB Port problem

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I have a Dell Latitude D840 laptop. I have been using an external drive
on the system to back up files and occasionally retrieve them. The
external drive is a pretty generic case with a Hitachi drive in it from
my old Dell. About 5 months ago, I plugged in the external drive and
got an error stating that the device had caused a power surge in the
USB ports and they would be shut down to prevent damage. I rebooted,
but the ports were fried. Dell replaced the mobo, and everything was
back to normal for a while. About a week ago, the drive quit working in
the laptop. It works great in a desktop, but not in that particular
laptop. I called Dell again, and they replaced the mobo again today.
This didn't fix the problem, though. So I used an externally powered
USB hub to connect the drive, and everything was fine.

Without the external power for the hub, though, the drive light will
turn on, and I can hear the drive start to spool up, but then it shuts
down again and starts over. The startup-shutdown process for the drive
takes about 1/2 second and repeats ad infinium. The device manager
reports either that there is no problem or that the drive cannot start.

I have re-loaded the drivers for the USB controllers and for the USB
ports, and for the drive, to no avail. I have tried a wireless mouse
transmitter in the ports, that works fine. The ports are both reported
to be supplying 500 mA, and the mouse controller is pulling 50 mA.

Any ideas here would be really helpful. The big confusion for me is
that the problem varied from port to port, there are two, for about
five months, then both went out. This says to me that something is bad
in the motherboard, but the new mobo should have fixed that.


Re: Dell Latitude USB Port problem

I think that the drive is just drawing more power than the laptop can
supply.  The solution here is kind of obvious, to power the drive
externally.  The only other option would be to get a new drive that
draws less power.  The drive probably draws 500ma, more or less (and
perhaps a lot more on startup), and the USB to IDE controller in the
drive case draws a bit also. wrote:

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