GOSSEN - Gossen Lunasix Repair Article

Comprehensive technical repair manual for the Gossen Lunasix 3 (S) light meter, a classic exposure measurement instrument. This workshop guide walks you through complete disassembly, internal cleaning, and full servicing procedures. You'll find detailed sections on cleaning the friction discs that control the self-rotating ISO scale mechanism, with step-by-step grease replacement using Molykote 44. The manual includes extensive photographic documentation of all three Lunasix 3 (S) variants, showing their respective weights (190g, 180g, 170g) and displaying every internal component fully dismounted. A major section addresses calibration and recalibration, featuring resistance tables, response curves, potentiometer identification charts, and circuit diagrams so you can verify and adjust the meter's accuracy. Calibration procedures are explained in detail using the Gossen Sixtomat Digital as a reference instrument, with practical guidance on achieving optimal measurement accuracy during adjustment. The manual covers important considerations including proper use of natural light sources during calibration, methodology for adjusting offset and slope parameters across both low and high measurement ranges, battery conversion notes, and housing closure requirements during potentiometer work.