Mamiya 7 65mm Lens: Sticking Shutter Blades from Residue
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 had an issue with sticking shutter blades. While this is often caused by oil contamination on the blades, this would not be common on a Mamiya 6/7 shutter. My only clue was a very small bit of what appeared to be oil on the spacer blade that hangs into the shutter opening when the blades are closed. Photo two shows this spacer with a very small amount of what appears to be residue.
To resolve this issue, the shutter needs to be removed from the lens and taken apart to the shutter blade level to clean everything, including not only the blades, but the blade operating ring and the mechanism plates.
As a matter of interest, photo three shows the disassembly beginning and the aperture input board being held in the tweezers. When the aperture is changed on the lens, the wiper, show on the left, connects the appropriate pads to provide various resistance (around 8K for f/4.5 down to around 1K for f/32) to input to the camera so the meter will know what aperture the lens is set to.
After cleaning, the lens is reassembled and the shutter checked electrically once the flex cable is reattached. The video shows the lens, almost reassembled on a test fixture that simulates the Mamiya 7 body so that all speeds can be tested.
