How to Trigger USB PnP connection?

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I have an external hard drive connected via USB.  It is supposed to
automatically be picked up by the computer's XP PRO SP2 when I turn it
on.  Sometimes it is,  sometimes not.  Many times I have to unplug the
drive and plug it up again to get the computer's PnP to detect it.  I
wonder why XP is missing its presence?  It is getting tiring to do all
the connects/disconnects.



Re: How to Trigger USB PnP connection?

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I have seen this problem caused by a partially defective USB cable, a bad
solder joint at on the USB connector at the PC or hard drive, a power supply
not providing enough 5 volts to the USB port, and a partially corrupted XP
system software.

You will need to identify the problem using the process of elimination.
Unless you have two computers I'd start by trying a different USB cable and
go on from there.

Intermittent problems are some of the hardest to identify since the problem
can not be made to occur on demand.

Re: How to Trigger USB PnP connection?

Jethro wrote:

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besides the great response by mist, i would add that you can
unplug/plug at the usb end or the AC end. You flick the on/off switch
at the AC end.

you say it's tiring. so maybe try that other way!  

Also, could try differnet usb ports of course. But that's just an easy
part of the larger troubleshooting thing that mist mentioned.

I had almost forgotton the word 'intermittent'.. It's not that
intermittent in such a bad way though, in that you aren't waiting
around for ages.. You don't have to 'keep an eye on it for a long time
and see if the problem persists' (a common instruction to an end user
when an intermittent problem). For you though it's Just a matter of
plugging it in and out, and you'll see the problem. I don't think
there's much you can do excep try diff usb ports, even a diff drive. In
the end most likely you'r going to have to not use something. hopefully
a usb port rather than a drive. Maybe you'll end up labelling a PSU
dodgy in that area. And that's if you get it solved.


Re: Re: How to Trigger USB PnP connection?

On 12 Aug 2007 22:35:58 GMT, ""

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I moved the USB connection on the computer to a second computer.  It
seems to work some better there, but still is intermittent.  I have
already tried switching USB ports with same results.  I have already
tried unplugging USB plug and power plug on the external case (yes my
internal drive is in a external case)  itself which almost always
works first time.

Thanks for response


Re: How to Trigger USB PnP connection?

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i meant switching the AC/MAins switch on/off. That may be near you, or
you could use an extension lead to make it nearer. THat may make it
less annoying . It's easier to flick a switch than plug/unplug a

But a really good thing i forgot to mention.

pci-usb adaptor .  will give you new working usb ports !!

you may also want to try switching your mbrd's usb off or on 5VSB.
Moreso off. 'cos it may be a PSU issue, maybe USB is supplied by 5VSB
and the 5VSB rail isn't supplying enough amps or volts or whatever to
the USB ports.

ps2 or usb could be on 5vsb
you can test if USB is on 5vsb if you have some usb speakers, see if
they get powered when you plug them in.
(side note- for testing if ps2 is on 5vsb, i plug a ps2 keyb in and
see the lights flash. Oddly, a usb keyb plugged into usb, doesn't
flash. A usb keyb with a usb-ps2 adaptor, plugged into ps2, does

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