Shane AO Electronics
Shane AO IRCAL Filter Stage, 
EL-3814
Schematic: schematics\SAO_ircal_filter_sh_1.pdf
Page last updated: November 20, 2012
Simplified Diagram - Refer to first page of schematic for more details
The Shane Adaptive Optics IRCAL Filter stage is a ThorLabs model FW102C comercial unit. The schematic shows how the unit is wired and how the feedback signal is wired to I/O bit 7 of Galil controller number one.
From the Thorlabs manual:
2.1 Changing and Removing Filters
Prior to changing filters, ensure that the power is off and the unit is disconnected from the DC source.
The filters can be changed by first removing the filter wheel cover, which is held in place with a single thumbscrew. Filters can then be inserted into the desired locations. The filters are secured to the wheel via SM1RR-1CT retaining rings, which are included with the unit. For easy access, the entire filter wheel can be lifted out of the filter wheel housing. Please note that the rear edge of the threaded filter holes contain a retaining lip that secures one edge of a Ø1" filter. Some filters with a Ø25 mm may need to be mounted between two SM1RR-1CT retaining rings.
When replacing the filter wheel in the housing, slip the wheel over the shaft and turn slightly to allow the gears to mesh. Replace the cover and tighten the thumb screw. It is not necessary to return the wheel to any particular orientation, since the unit will reorient automatically when the power is turned on.