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>
