I have an HP 6213 power supply that has , +, - and ground terminals, hence a Bi-polar supply. The thing is, the negative side stopped working so now I can't power things that require a negative as well as positive voltage, mostly op-amps. It does not seem to be something simple like an old capacitor. Does anyone have any experience with this supply? It is the small green box-type, and if not, any suggestions on how to get it fixed? Thanks Matt mwb5@njit.edu -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist