AS-4000 User’s Guide Maintenance Cleaning procedure A Open the cover of the color measurement unit. B Clean the white calibration tile. Wipe off any dirt from the surface of the white calibration tile with a dry woven polyester/nylon knit cloth. C Close the cover of the color measurement unit. This completes this section. Cleaning the Spectrum Sensor Module If the spectrum sensor module, which measures color in the color measurement unit, is dusty and so on, it may affect the color measurement results. 86