One of my problems in solving this problem is that the industrial computers we use, pass the ESD tests with this mouse. The 2 systems that are failing have Dell computers. One is a Dell Optiplex 760 and the other is a Dell rack-mount server. I don't know if better grounding was used on the industrial motherboards and chassis, or if the Dell computers are more sensitive to ESD events. It appears from testing that we are not grounding the cable shield as it enters the stainless steel enclosure. A separate ground wire was attached to the mouse shell, then to the enclosure, which passed the ESD tests. I have some components ordered which should help me ground the cable shield to the enclosure, just inside the enclosure entry point. I know that a feed-through grounded cable gland would be preferred, but it aesthetically does not look good. I'll let you know if it works, but I definitely will test to see at what level it fails, like Doug suggested.
Thanks, John From: [email protected] [mailto:[email protected]] On Behalf Of Doug Smith Sent: Wednesday, January 06, 2010 1:16 PM To: John Woodgate Cc: [email protected] Subject: Re: [PSES] ESD Test Failure of Stainless USB Mouse Hi Everyone, Just a thought on ESD testing. The actual failure level should always be determined, not just that the test was not passed. For instance, suppose you are trying for 4 kV contact mode but fail and the failure happens at 1.5 kV. You try something, but unit still fails. However, the failure level increased to 3 kV. This is very important. Either more of the same technique should be tried or you have peeled one layer of the ESD onion and now another mechanism controls the response. I recently had a product that had three distinct mechanisms and all had to be fixed simultaneously for the product to work. A solution would never happen if one tried experiments one at a time and just looking at the pass-fail state on a product like this. Doug On 1/6/10 7:06 AM, John Woodgate wrote: > In message > <769907F0D19EFA45BD6F04FC6E896D6D220970D160@GVW0538EXC.americas.hpqcorp.n > et>, dated Wed, 6 Jan 2010, "Conway, Patrick R (bNB Houston)" > <[email protected]> writes: > >> 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. > > If totally confused, change the test gear. (;-) -- ___ _ Doug Smith \ / ) P.O. Box 1457 ========= Los Gatos, CA 95031-1457 _ / \ / \ _ TEL/FAX: 408-356-4186/358-3799 / /\ \ ] / /\ \ Mobile: 408-858-4528 | q-----( ) | o | Email: [email protected] \ _ / ] \ _ / Website: http://www.dsmith.org - 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 <[email protected]> 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 <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]> - 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 <[email protected]> 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 <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
