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'[EE] USB devices resetting PC upon plug-in'
2006\05\22@113155 by Aaron

picon face
My computer at work has a very frustrating and nasty habit of resetting
when I plug in a USB device.  Sometimes.  Must have something to do with
the phase of the moon or dead fish as it doesn't always do it.  :)

It will also (sometimes) reset if I take a meter lead from my Fluke and
just touch it to the metal rim surrounding the outside of the USB
connector.  The other end of the meter lead can even be disconnected
from the meter.

Before I complain the the IT guy, has anybody ever seen anything like
this before?

Aaron

2006\05\22@115512 by M. Adam Davis

face picon face
The metal shield should be grounded.  I'd be interested in the
resistance from the metal shield to the ground pin of the power cord,
and whether the outlet is correctly grounded.

Do all of the USB ports react similarily?  There may be some on the
front and rear of the computer.  Those on the front may be connected
to the motherboard by faulty wiring.

If you experience no other problems with the computer (rebooting with
other peripheral connects/dsiconnects) then the fix may be as simple
as adding a USB card to the computer and using those ports instead of
the one that's built in that's failing.

As far as talking to the IT guy, try to find a method (a particular
USB device, etc) that will consistantly demonstrate the problem
quickly.  Ideally you can get to the point where it resets every five
insertions (after five tries they'll get board and start reading your
cubicle posters)

-Adam

On 5/22/06, Aaron <spam_OUTaaron.piclistTakeThisOuTspamgmail.com> wrote:
{Quote hidden}

> -

2006\05\22@124707 by Peter

picon face


On Mon, 22 May 2006, Aaron wrote:

> My computer at work has a very frustrating and nasty habit of resetting when
> I plug in a USB device.  Sometimes.  Must have something to do with the phase
> of the moon or dead fish as it doesn't always do it.  :)

More likely the grounding is floating in air somewhere.

Peter

2006\05\22@125221 by John Pfaff

picon face
Sometimes when I plug in my Zaurus (PDA by Sharp that runs Linux
out-of-the-box) my PC will reset, but only if I plug in the cable to the
PC before I attach the Zaurus.  I haven't seen it happen if I plug the
Zaurus in to the cable, then the cable into the PC (at least not yet).  
I've also seen it happen if the cradle is attached to the PC and I set
the Zaurus in the cradle.  Again, if the I attach the cable to the PC
while Zaurus is in the cradle it's OK.

Aaron wrote:
{Quote hidden}

2006\05\22@161747 by Richard Prosser

picon face
I've had this happen with a home-made USB connector that appears to
momentarily short the +5V line on the USB connector to "something
else".
If there is a lot of free play in the connector see how you can create
the problem consistantly or better yet, avoid the problem
consistently.

RP

On 23/05/06, John Pfaff <.....jpfaff1528KILLspamspam@spam@verizon.net> wrote:
{Quote hidden}

> -

2006\05\23@080059 by Aaron

picon face
M. Adam Davis wrote:

>The metal shield should be grounded.  I'd be interested in the
>resistance from the metal shield to the ground pin of the power cord,
>and whether the outlet is correctly grounded.
>  
>
The metal shield is grounded.  Less than 0.5 ohms to the power cord's
ground pin.  As measured with a Fluke 87.  The outlet is wired &
grounded properly.

>Do all of the USB ports react similarily?  There may be some on the
>front and rear of the computer.  Those on the front may be connected
>to the motherboard by faulty wiring.
>  
>
Front USB ports are the ones that show the problem - rear ones seem to
be OK, but I rarely try to use them.

>If you experience no other problems with the computer (rebooting with
>other peripheral connects/dsiconnects) then the fix may be as simple
>as adding a USB card to the computer and using those ports instead of
>the one that's built in that's failing.
>  
>

Computer otherwise works fine.

>As far as talking to the IT guy, try to find a method (a particular
>USB device, etc) that will consistantly demonstrate the problem
>quickly.  Ideally you can get to the point where it resets every five
>insertions (after five tries they'll get board and start reading your
>cubicle posters)
>  
>
Demonstrating it shouldn't be a problem.  Happens 90% of the time.  Got
any good Dilbert/IT posters I can hang up in preparation for their
visit?  :)

>-Adam
>  
>
Forgot to mention the only USB device I ever plug in is a memory stick.  
Most of my real work gets done on the laptop...no IT department insanity
on that one. :)  If I power down the computer and plug in the memory
stick and start it up, it works fine.  No amount of wiggling can trigger
a reset.  Even unplugging the memory stick is fine.  Just the fact of
plugging it in and tapping the outside rim of the USB port (in
preparation for insertion) causes the reboot.

Aaron

2006\05\23@080327 by Aaron

picon face


Peter wrote:

{Quote hidden}

Nope, see my other response to Adam Davis.

Aaron

2006\05\23@082503 by Rolf

face picon face
Aaron wrote:
> M. Adam Davis wrote:
>
>  
> [snip]
>>  
>>
>>    
> Demonstrating it shouldn't be a problem.  Happens 90% of the time.  Got
> any good Dilbert/IT posters I can hang up in preparation for their
> visit?  :)
>
>  
> Aaron
>  


All the good sysadmins went off dilbert a long time ago.... good
sysadmins now read UserFriendly.... ;-)

http://www.userfriendly.org/

Rolf

2006\05\23@101147 by M. Adam Davis

face picon face
The only thing I can think of (given a reset happens when you touch
the shield with an unconnected lead)  is that a bypass cap or two on
the motherboard near where the front USB connectors attach are no
longer useful.

0.5 ohms with a few thousand volts (electrostatic discharge) is enough
to cause the ground line to drive other low impedance wires.
Depending on the motherboard routing you may be causing a data bus
fault that causes a reset or you may actually be driving the reset
line (which is sometimes routed near the front of the motherboard for
case switches which are usually no longer installed)

Easy cheap fix - get a USB extension (male A to female A) and use the
back ports.

Easy fix - get a USB hub and connect it to the back ports.  Could
probably connect it to the front without a problem as well.  Given how
cheap these are getting you may find this as cheaply as - or cheaper
than - the cable above, and it's a better solution.  Try to get one
with its own power supply - I would treat your PC power supply as
suspect.

Ideal fix - replace the computer.  This should not be happening and
may indicate worse problems.  Of course, my inlaws have a computer
whose USB was blown up by lightning (USB DSL modem), and the video
chipset went bad.  Still works - new video card, new USB card, and
everything is still running just fine.  So you may be okay with the
simple fixes above- it's a risk/reward calculation you (or your IT
dept) gets to make.

-Adam

On 5/23/06, Aaron <aaron.piclistspamKILLspamgmail.com> wrote:
{Quote hidden}

> -

2006\05\23@102223 by Mike Hord

picon face
> Ideal fix - replace the computer.  This should not be happening and
> may indicate worse problems.  Of course, my inlaws have a computer
> whose USB was blown up by lightning (USB DSL modem), and the video
> chipset went bad.  Still works - new video card, new USB card, and
> everything is still running just fine.  So you may be okay with the
> simple fixes above- it's a risk/reward calculation you (or your IT
> dept) gets to make.

That seems a bit harsh.  If it's just a cap on the little
daughterboard on the front of the case where many PCs keep their USB
jacks, replace that and see what happens.

Mike H.

2006\05\23@105628 by kravnus wolf

picon face
> Forgot to mention the only USB device I ever plug in
> is a memory stick.  
> Most of my real work gets done on the laptop...no IT
> department insanity
> on that one. :)  If I power down the computer and
> plug in the memory
> stick and start it up, it works fine.  No amount of
> wiggling can trigger
> a reset.  Even unplugging the memory stick is fine.
> Just the fact of
> plugging it in and tapping the outside rim of the
> USB port (in
> preparation for insertion) causes the reboot.
>
Open the casing and check for connectivity between the
USB wires when tapping them. There maybe a short
circuit.

John

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2006\05\23@184902 by Brendan Moran

flavicon
face
I get a similar problem at my work.  I have a USB hub that will
sometimes spontaneously die when I plug my USB drive in.  If I just
leave it alone for a minute, it will recover.

This all started, however, after a power surge in my building.

My hub is built from two CY7C65640-LFCs. Only one of them blew.  As I
work for an elex company, I had two ICs brought in, and replaced the
faulty one.  This is all fine except for that one annoyance.  And just
like with your problem, it only happens sometimes.

The idea about the faulty caps sounds good.  Also sounds easy to fix for
my situation.

Some of that might help you out.

If nothing else, ask your IT guys for a better surge protector.

--Brendan

Aaron wrote:

{Quote hidden}

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