Changing the Aperture
The 939 instrument was designed to allow you to quickly change the aperture and target window. X-Rite provides three aperture kits especially designed for the instrument. These Available kits are 4mm, 8mm (standard), and 16mm. To change the aperture size:
1. Unplug the AC adapter and click the battery switch to the Off position.
2. Hold the shoe next to the instrument housing and lift upward on the spring-loaded latch. Open the shoe perpendicular to the instrument housing. Refer toUnlatching the Instrument Shoe in Section One of the operators manual.
3. Carefully rotate the instrument over and rest it on its top.
4. Using your fingers, rotate the sensor nose to the left (counter-clockwise) until it stops.
5. Carefully remove the sensor nose by lifting upwards and set aside.
6. Position the appropriate end of the aperture wrench on the existing aperture and remove by turning to the left (counter-clockwise) until it is free. Set existing aperture aside. CAUTION: Extreme care should be taken not to contaminate the optics with any dust or dirt when installing the new aperture.
7. Align new aperture over opening in optics and secure by using the appropriate end of the aperture wrench.
8. Position corresponding sensor nose over the optics opening in the bottom housing and rotate to the right (clockwise) until it stops.
9. Using your fingers, press the target window out from the topside of the shoe. Press against the ring and not the clear window.
10. Note the alignment of the new window and snap it into place from the bottom side of the shoe.
11. The aperture setting in the instrument must now be set to match the new size.