Mamiya 80mm C Lens: Replacing the Seiko 0 Speeds Escapement
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
Servicing a Mamiya 80mm C lens. This lens had several issues, main one being that the shutter was not working properly at the slow speeds. Usually, cleaning the speeds escapement will resolve this but in this case, I needed to replace the speeds escapement to get consistent shutter speeds.
Mamiya used five slightly different versions of the Seiko 0 shutter for their C series lenses (I am referring to the black shutters, early on they used chrome front shutters). And many of the parts do not interchange. Unless you look very carefully, all these shutters look alike. Photo three shows two speeds escapements, they both came out of so called “blue dot” Seiko shutters and they are not interchangeable.
The shutter that I am servicing in the photo is what Seiko called a 730 (Tentative) model. The later 730, looking identical externally, used several different parts (including the speeds escapement). So you often do not know what model you have until some disassembly is done. That’s one reason I have to stock so many parts for these shutters!
