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Changing Filters in the Main (A&G box) slides

The main neutral density and colour filters are held in two 5-position slides in the lower section of the A&G box. To change a filter within these slides the filter should already be mounted in a holder, which can be obtained from RGO technical staff.

To access one of the filter slides the slide to be accessed should be moved to position zero (out of the beam), and the other slide should be moved into the beam. For instance to access a filter in the COLOUR slide type:--

MAINFILTC OUT
MAINFILTND 4.

The access door on the A&G Box can then be unlocked with:--

AGACCESS.

This command will unlock the access door and will not return control to ICL until the door is locked again. The door is on the lower half of the A&G box, and has a shiny metal latch which can be opened manually. To remove the filter slide from the drive shaft a 3mm Allen key will be required. With the access door open an Allen screw can be seen in the centre of a rectangular latch which holds the filter slide in place. This screw should be removed and the rectangular latch can be swung aside, to allow the filter slide to be withdrawn from the A&G unit. The filter holders can then be interchanged using the same Allen key. The slide can then be inserted; the latch and Allen screw replaced. The access door can then be closed and latched. The AGACCESS procedure should then return an ICL prompt; and the interlocks should then be released. However the microswitch which detects that the door is closed does not always operate, and it may be necessary to open and close the door again until it does.