We found out all about this in error after a software configuration issue. Leon has manuals for the 671 control boards that are found (one per mirror) in the Sutter MDR-6 control box. If you hear a loud resonance noise from scanners (often higher pitch than expected) turn off control unit, check software config and if all else fails consider tuning. Leon and Jamie know about this. Leon says that he has had to retune a couple of times for no particularly good reason and the mirrors have gone on to behave fine afterwards.

Tuning basically requires

• Taking the top off the MDR6
• identifying the mirror control board for the mirror with trouble
  • presumably the fast/X mirror
• getting the position signal off one of the pins on the J4 8 pin connector 671 connector
  • Howard from electronics made a simple adapter
  • Be very careful not to let any of the bare wire endings touch the grounded case (or anything else)
• … OR using an oscilloscope type probe to hook onto some rings on the board
• Hook up command and position signals to ITC18 / Igor and give suitable steps
  • suggestion 50mV command, 30 Hz initially
  • then whatever was giving the resonance.