Periodically, PRIMUS receives a call from the field regarding the incorrect insertion of a PSS500 EPROM. A number of years ago, this was fairly common, but with the evolution of consumer electronics, many end users have had exposure to control boards and understand how to properly key and insert an EPROM.

Proper Insertion of PSS500 EPROMS

All EPROMS have a key on one end which needs to match up with the socket mounted on the electronic circuit board. Care must be taken to prevent bending the pins when inserting an EPROM. Failure to properly insert this key typically applies power to the wrong part of the EPROM and severely damages it. The only solution at that point is to order new CAL and OPER EPROMS from PRIMUS using the Job Number and/or Serial Number of the sterilizer. PRIMUS only sells EPROMS in matched sets.

Below are photographs demonstrating the proper keying of the EPROMS on a PSS500 control board. Any work performed on solid state components should only be conducted utilizing a personal grounding method. This will ensure any static charge is discharged to ground prior to handling the solid state component.

Have a question or having difficulties? Talk to Dave Schall, our PRIMUS sterilizer expert who is here to assist you anytime at 877.679.7800 extension 1212 or email at

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