'Unknown device'

[Andre De Clercq]

On my xpsp2 pc I have a USB connector on the media bay and several on the
rear panel. They all work flawlessly with several USB devices. Today however
I got an MP3 player which was not recognized by the front connection
(unknown device), but worked perfectly on the back connections. Could
anybody give a hint why this happens? Thanks.

 

[Guest]

Andre,

Your MP3 player should have come with a CD containing the Windows drivers
necessary for communicating with the player through the USB interface. Many
MP3 players also come with application software on the CD that can be used to
transfer songs onto the player.

If your player did not come with a CD you might find the necessary drivers
and other software on the manufacturer's website.

 

[Andre De Clercq]

Thanks John, and indeed I have the CD which keeps saying that only Windows
98 needs drivers, and doesn't install them on my XPSP2. If drivers were a
must, why does the player do all I want when plugged into the back USB
connectors? The front connector itself is OK because there is no problen to
connect a memory stick, an exeternal HDD...

 

[Guest]

Sorry, I should have paid more attention to the details in your original
post. What you are seeing could happen if the front and rear connectors are
on different USB hubs or controller with different chip sets. You might be
able to determine this by looking in the Device Manager.

Have you tried going into the Device Manager and doing a rescan? You might
also try plugging in the MP3 player then restarting the computer with the
player plugged in.

Are you using a cable to connect the MP3 player or does it plug directly
into the USB port? If you are using a cable, the length of the internal cable
to the front media bay plus the length of the cable connecting the MP3 player
may be causing a problem.

 

[Andre De Clercq]

Thanks again John for your time and advise. It has indeed to do with the
cable length (very strange...). I will report more to morrow...it's over
midnight here..

 

[Andre De Clercq]

Strange things happen...
When I add to the 3 feet USB cable another 3 feet extension cable, the
device is being recognised (most of the time), BUT, when I connect with the
short cable the devise is no longer recognised as an"unknown device" but
apparently Windows shuts off the connection, even for other USB devices
when connected to the bay. And even more strange is that after this USB
shutoff my computer doesn't shutdown anymore (keeps prompting "computer is
shutting down"). I have to keep the powerswitch pressed to shut it down.
Why is all this happening? Bad USB MP3 player?...but works perfect on two
other computers..Thanks for any advise.

 

[Guest]

Many cables that are bundled with hardware are not of the highest quality.
I've run into lots of problems with inexpensive USB cables that only worked
some of the time and I believe it has to do with the cable's internal
impedance. This could explain why you were able to get it somewhat working by
adding an additional 3 foot extension cable. When dealing with the high
frequencies associated with USB 2.0 transfers it is important that the
impedance of the cable matches that of the device and hub.

 

[Andre De Clercq]

Thanks John. And it remains strange that a corrupted USB connection can
lock-up the computer.