GOSSEN - Gossen Lunasix Repair Article

Comprehensive technical guide dedicated to the repair and complete servicing of the Gossen Lunasix 3 (S) light meter. This document covers the full disassembly and maintenance procedure for this classic light measuring instrument. Main sections include thorough cleaning of internal mechanisms, particularly the friction discs responsible for self-rotating ISO scale functionality, and grease replacement procedures using Molykote 44. The guide features extensive photographic documentation showing all three Lunasix 3 (S) variants with their respective weights (190g, 180g, 170g) and displays every internal component in detail. A significant section addresses calibration and recalibration procedures, presenting resistance tables, response curves, potentiometer identification charts, and PCB circuit diagrams. Calibration procedures are thoroughly detailed with reference measurements using the Gossen Sixtomat Digital as comparison instrument, complemented by practical advice for achieving optimal accuracy during adjustment. Important recommendations cover the use of natural light sources and methodology for adjusting offset and slope parameters across both low and high measurement ranges. The document also includes troubleshooting tips regarding battery conversion considerations and housing closure requirements during potentiometer adjustment.