Hi John-
I know you have received a lot of advice re: grounding,
shielding and isolation.
But so far you have not identified which is
the cause – either the mouse or the PC.
I agree with Charlie Blackman’s comments: a few debug steps
can be taken to help isolate the problem:
1- Keeping all other parameters the same, swap the mouse, re-test, then
swap the PC, and re-test.
a. use a completely different mouse type and completely different PC.
b. Try to determine if the problem follows the mouse or follows the PC.
The results from that debug should remove a lot of uncertainty
about the source of the problem.
At a minimum it will remove ½ of the
configuration as not being the root cause.
Good luck, and keep us posted on your progress.
From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of John Cochran
Sent: Tuesday, January 05, 2010 12:44 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: RE: [PSES] ESD Test Failure of Stainless USB Mouse
The bottom is metal, but a separate piece. It is connected by a soldered
ground braid between the parts. Problem with connecting to the enclosure
underneath is not scratching the etched mouse pad surface or marking up the
enclosure surface. At one time the shell was not connected to the cable
shield and it caused greater problems, because the charge was definitely going
through the circuit board.
John
From: Ken Wyatt [mailto:k...@emc-seminars.com]
Sent: Tuesday, January 05, 2010 1:31 PM
To: John Cochran
Cc: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] ESD Test Failure of Stainless USB Mouse
Hi John,
Does the mouse have a metal bottom, as well? You'll want to divert the bulk of
the discharge out the bottom to earth with a direct path as possible. Examine
the discharge path carefully. It may be passing through the internal circuit
board on the way to earth. The object is to control the path of discharge
current, to avoid any electronics, allowing it to return to earth with a short
path.
Ken
Wyatt Technical Services, LLC
56 Aspen Dr.
Woodland Park, CO 80863
Email: k...@emc-seminars.com
Web: www.emc-seminars.com
http://www.linkedin.com/in/kennethwyatt
(719) 310-5418
On Jan 5, 2010, at 11:13 AM, John Cochran wrote:
During testing of an industrial control system, with a custom stainless steel
USB mouse, ESD testing failed. The standard used was IEC 61000-4-2,
Electrostatic Discharge. When a -4KV discharge was applied to the metal
housing of the mouse, the mouse and/or USB keyboard would stop functioning.
The function returned after testing, only if the USB connection to the
computer was broken and connected again. Suspected the ESD charge was
disrupting the USB communication in the computer, since the cable shield is
the only path to earth ground. Tried to break the cable shield and connect
the mouse end to the enclosure (earth ground), with no improvement. Looped
the cable through an Intermark RFC-20 ferrite which helped to pass testing,
marginally. Does anyone have any good suggestions for eliminating the
interruptions causes by a contact ESD discharge on a metal shelled USB mouse?
John Cochran
215-443-3400 x193
-
This message is from the IEEE Product Safety Engineering Society emc-pstc
discussion list. To post a message to the list, send your e-mail to
<emc-p...@ieee.org>
All emc-pstc postings are archived and searchable on the web at
http://www.ieeecommunities.org/emc-pstc
Graphics (in well-used formats), large files, etc. can be posted to that URL.
Website: http://www.ieee-pses.org/
Instructions: http://listserv.ieee.org/request/user-guide.html
List rules: http://www.ieee-pses.org/listrules.html
For help, send mail to the list administrators:
Scott Douglas <emcp...@socal.rr.com>
Mike Cantwell <mcantw...@ieee.org>
For policy questions, send mail to:
Jim Bacher <j.bac...@ieee.org>
David Heald <dhe...@gmail.com>
-
This message is from the IEEE Product Safety Engineering Society emc-pstc
discussion list. To post a message to the list, send your e-mail to
<emc-p...@ieee.org>
All emc-pstc postings are archived and searchable on the web at
http://www.ieeecommunities.org/emc-pstc
Graphics (in well-used formats), large files, etc. can be posted to that URL.
Website: http://www.ieee-pses.org/
Instructions: http://listserv.ieee.org/request/user-guide.html
List rules: http://www.ieee-pses.org/listrules.html
For help, send mail to the list administrators:
Scott Douglas <emcp...@socal.rr.com>
Mike Cantwell <mcantw...@ieee.org>
For policy questions, send mail to:
Jim Bacher <j.bac...@ieee.org>
David Heald <dhe...@gmail.com>
-
This message is from the IEEE Product Safety Engineering Society emc-pstc
discussion list. To post a message to the list, send your e-mail to
<emc-p...@ieee.org>
All emc-pstc postings are archived and searchable on the web at
http://www.ieeecommunities.org/emc-pstc
Graphics (in well-used formats), large files, etc. can be posted to that URL.
Website: http://www.ieee-pses.org/
Instructions: http://listserv.ieee.org/request/user-guide.html
List rules: http://www.ieee-pses.org/listrules.html
For help, send mail to the list administrators:
Scott Douglas <emcp...@socal.rr.com>
Mike Cantwell <mcantw...@ieee.org>
For policy questions, send mail to:
Jim Bacher <j.bac...@ieee.org>
David Heald <dhe...@gmail.com>
