Wow, I have seen a similar fault on PICs, I had a project that would run fine on my 5V power supply but fail in the unit with it's wimpier power supply. I believed at the time that I had some pins that were either zapped by static electricity, or had lost a Bus Fight*. How about overvoltage protection on your board? Is there a chance spiky juice is coming in through the power supply or through an external pin? -- Lawrence Lile *Bus Fight: Usually started when somebody throws an apple core at the bus driver but misses. Olin Lathrop Sent by: pic microcontroller discussion list 01/08/2003 02:06 PM Please respond to pic microcontroller discussion list To: PICLIST@MITVMA.MIT.EDU cc: Subject: Re: [EE]: Damaged ICs > It seems reasonable that the power supply that this customer is using is > occasionally doing something that our board finds disagreeable, but what? > And why only when first assembled and never in the field? It would be > extremely helpful if we had some idea what to ask this customer to > investigate... > > I'm hoping some of you PIC-listers might present some opinions that help > solve the problem - or at least help us start asking questions that lead to > a solution. This is just a wild guess, but maybe their power supply brings the various voltages up in an unusual order, maybe caused by other equipment also installed in the PC. This could cause I/O pins to be driven before the chip is powered up, which could cause latchup and damage to those parts. ***************************************************************** Embed Inc, embedded system specialists in Littleton Massachusetts (978) 742-9014, http://www.embedinc.com -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics