Hi Dave, Those were the days. Computer not working, pull out all the cards and take an eraser to the gold fingers. Put it back together and Voila! everything works.
In a perfect world, my opinion coincides with those previously expressed. We should be testing with pristine equipment, as a customer can expect to receive. This means items direct from the manufacturing process. Perhaps many of the esteemed members of this group are in positions that afford them these resources. My personal experience has been one of receiving the latest prototype that has been passed around through many hands and has little cosmetic resemblance to that shipping to customers. In these situations, I believe that it is of mandatory importance, if your equipment is a card slot type or has removable parts/panels, to try to return the item to as pristine a condition as you can prior to test. There is just as much probability of connection debris preventing a ground loop that would have increased emissions/susceptibility as there is for it reducing them. To the specific question of the eraser: I heard a couple of eons ago that pencil erasures leave a contaminating residue and they should not be used, especially on gold flash, leading me to seek alternatives to the Good 'ol Days mentioned above. I use contact cleaner made for noble metals on edge fingers and frequently use a 50:50 mixture of denatured alcohol and distilled water to clean gasketing materials to remove oil and dust deposited by handling. One other design type note: If you are using steel, think about zinc plating. It is well worth the money. Your finish should not be so fragile if expected to stand up to normal wear and tear. Have a Great Day! Dave -----Original Message----- From: David Heald [mailto:[email protected]] Sent: Thursday, February 28, 2002 11:44 AM To: [email protected] Subject: Pencil erasers for pre-EMI cleaning? All, I'm preparing for an emissions test and I had started cleaning some of my chassis mating surfaces with a pen/pencil eraser then alcohol to ensure the surface to surface contact was good. A friend then told me that using an eraser would also remove the anti-corrosive coating that was on the metal (Thanks Paul!). So I would end up with a very short term benefit, then rust. What I am trying to determine is if maybe light rubbing with a pencil eraser might only remove surface contaminants and leave the metal and coatings intact. (the pencil eraser is much less abrasive than the pen side) So the real question is... Does anyone have direct good or bad experience with the aftereffects of using a pencil eraser to clean mating edges (card faceplates in a telco box for example)? I have both steel and aluminum surfaces to worry about so info for either type is welcome. (and don't worry the different metal types are not adjacent). Any feedback would be greatly appreciated as the system is really dirty right now. Thanks and Best Regards, Dave Heald ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
