In message <4ced7e8b.9020...@emcesd.com>, dated Wed, 24 Nov 2010, Doug Smith <d...@emcesd.com> writes:
>Sometimes the shield can cause high frequency problems as it is just a >thick wire. I documented this in a paper published at the EMC'94 Roma >Symposium. One problem can happen when CM shield currents land on a PC >chassis and then get into the internal circuits through seams in the >chassis. This is what I described in the Roma '94 paper. It's known in professional audio as the 'Pin 1 problem', because the shield is connected to pin 1 of the standard 3-contact XL connector. If you connect pin 1 to the printed board, you inject all the CM signals where they can do the most damage. Pin 1 should be connected to the (conducting) enclosure, preferably to its outside surface, thus preventing UHF and above signals radiating >from the inside surface to parts on the board. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK If at first you don't succeed, delegate. But I support unbloated email http://www.asciiribbon.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 <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ 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...@radiusnorth.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
