Urgent help needed: can't power off PC

[Terry Pinnell]

I installed a 4-socket self-powered USB hub today on my XP Home PC. My
various USB devices seemed to work OK (with exception of the new one,
a QX3 microscope, that had prompted the purchase, but that's a
separate issue). Here's a picture of it:
http://www.terrypin.dial.pipex.com/Images/USBHub.jpg

But, on switching off my PC, which seemed to power down as usual, the
amber and green power lights on the Mesh Athlon 1800 didn't go out.
And the PC wouldn't then respond to being switched on again. Nor did
Reset have any effect. Nor holding the power button depressed. Serious
worry and seems to defy logic.

The power lights would go out if I removed either the DC power to the
hub, or the USB lead connecting it to the PC. But even then the PC
wouldn't start up again. Removing and replacing mains plug, or on/off
button at rear of PC had no effect either

Somehow, after fiddling around, cursing a bit, it DID then respond.
But naturally I am now very nervous about switching it off. Using
Start>Turn Off Computer>Restart works OK - it's just the full Turn Off
that doesn't.

There's nothing to help in the single page 'User Manual' (headed USB
1.1 Hub GUH-01 GUH-02, with no contact or web info.

Can anyone offer any help please?

 

[Guest]

Have you checked/changed the power options in your system
Bios? Worth a look.

 

[Terry Pinnell]

Have you checked/changed the power options in your system
Bios? Worth a look.

Thanks, no I haven't. One more thing to try. Meanwhile, I now reckon
the power problem (as opposed to the microscope problem) is a
fundamental design issue, caused because the arrangement must look
like this:

External
5V supply
|
|
diode \/
--
| USB DC supply bus
|_____________________________
|
|
|
/\ diode
--
|
|
Internal
5V supply


The same behaviour occurred when I connected the powered USB hub to my
alternative W98 PC in my shed/workshop. It's incredible that the
manufacturer makes no mention of this fundamental flaw in the
accompanying sheet ('User manual'!)

I side-stepped the problem by removing the USB DC supply before using
Turn Off. In fact, I've now removed the powered hub altogether, as I
can't get the device (Digital Blue QX3 microscope) working on my XP PC
anyway, with or without it. And, after much effort and totally
inconsistent behaviour, I have got it working on my W98 PC, without
the hub.

=========================

On the microscope issue, elsewhere (the asus mobo newsgroup) I had a
post advising that sw doesn't work on XP. Which if so is a revelation!
I had given suppliers, Digital Blue, a detailed description of what
was happening on my XP PC, and they didn't so much as mention any of
those key points. In particular, no suggestion that sw doesn't RUN on
XP...

I had mixed success on my alternative W98 PC. I did get it running on
Saturday, after several hours involving half a dozen installation
attempts. But then when I tried Sunday it failed. Again it was that
'Having trouble communicating' message, as on XP, interspersed with
messages telling me microscope wasn't connected, when it plainly was.
I then tried with a self-powered USB hub I'd ordered specially, but
that gave no more joy.

Then, suddenly, late yesterday afternoon, it started working. No idea
how or why. I had done nothing special. It was just one more desultory
attempt (connected to one of the direct USB sockets, not to the
powered hub, although I suspect that's irrelevant.) I expected it to
then fail next time I booted/reran. But so far, over several repeat
runs yesterday, it still ran OK. Of course, when I try TODAY, that
might be back to square one again. Go figure...