At 02:52 PM 4/6/2006, Wouter van Ooijen wrote: >I customer returned a motor controller to me. It contained two parallel >1 Ohm carbon resistors, which both had failed open. Nothing to be seen >on the outside, just infinite (> 5 MOhm) and high (~ 500kOhm) >resistance. Is this a known failure mode? Possible causes? Seen if often. Metal film and carbon film both have lousy peak power ratings. I tend to use wire-wound or metal oxide resistors in those applications. Watch out for just which metal oxide resistors you get. The ones I have had the best luck with have a continuous film over the entire surface of the resistor. Those with a spiral cut do not have as good a peak power rating as those without. dwayne -- Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 22 years of Engineering Innovation (1984 - 2006) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist