Mamiya 7 65mm Lens: Shutter Not Latching, Release Magnet Cleaning
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
This Mamiya 7 65mm lens arrived with the symptom of a non-latching shutter. Whenever the wind lever on the camera was wound, the shutter would release on its own.
While this is obviously caused by part of the release mechanism not latching and while I would suspect the release magnet, I would not know until the shutter was apart at some level.
Photo three shows the shutter with some disassembly to access the mechanism and the release magnet is the red one at the top. Sure enough, it was not latching when the shutter was wound. This is usually caused by contamination on the magnet surfaces. Photo four shows a close up of the magnet surfaces, hard to see but there is contamination on the facing parts that is preventing the magnet to latch. These are actually combination magnets, part permanent magnet and part electromagnet, very common on cameras.
Photo five shows how I clean the surfaces with a tissue and contact cleaner and then in photo six I use a thin burnisher on the contacts.
When these sorts of issues come into the shop I generally estimate them for the worst case which is a complete shutter replacement. When it turns out not to need a new shutter, everyone is happy as the repair cost is greatly diminished.
