After installation of a PSS5 control board, the technician finds that some of the output relays are not being actuated.


Check the jumpers that are located out of sight under the SBC196 board and check the MP (Master Power) jumper for the proper configuration that matches the respective sterilizer’s output relay arrangement on the OPTO22 relay board.

The SBC196 board is often referred to as a “mezzanine board” because it is a small board attached to a larger control board. To reveal the jumpers, separate the SBC196 board from the control board by removing its 4 fasteners, noting the arrangement of the standoff sleeves and washers. Carefully lift the SBC196 board from its sockets.

If the relays are in the proper locations as defined by the software and sterilizer configuration, you can find the jumper settings by remembering the following:

  • Every output relay (the black relays and the pink buzzer relay) on the OPTO22 board gets a corresponding jumper under the SBC196 board, except for the Master Power relay which has its own jumper.

The Master Power relay jumper choices are labeled MP15, MP16, and MP23 and are found between the wide ribbon cable and the SBC196 board. If the Master Power relay is found in position 23 of the OPTO 22 relay board, then the MP23 pins must have the jumper. If the MP relay is found in position 15, then MP15 must be jumped.

The jumpers that are located under the SBC196 board are arranged in three (3) rows with letter designations. Jumper A is for relay position 0 on the relay board. Jumper B is for relay position 1. Jumper C is for relay position 2, D for 3, E for 4, etc.

It is typical to have the output relays located in relay positions 0 through 7. Therefore, there needs to be jumpers on A, B, C, D, E, F, G. Depending on the sterilizer configuration, there may be output relays in other locations, so just use this information to determine which pins need jumpers.

The white input relays do not get jumpers.

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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