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Aperture repair in Komuranon zoom 35-70 3.5-4.5
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PostPosted: Sun Sep 22, 2019 4:29 pm    Post subject: Aperture repair in Komuranon zoom 35-70 3.5-4.5 Reply with quote

Hello fellows, I ask for your hints and help for a nice and rather massive Komuranon zoom 3.5-4.5/35-70 on OM mount that I've received.



It zooms and focuses well, but the aperture does not move in any situation, neither when I push the side "ears" for automatic diaphragm management.

I said to myself I may try to fix it myself, if for example the spring slipped off its screw somewhere i the mount. Sorry for the "primitive" dust, I swept it after I took the shots.



So I unscrewed the four mount screws (the larger ring) and lifted off the mount. Here it is from the inner side, with a very small pin that does not connect with the aperture but targets the small AM switch.



Inside the mount I discovered a plastic gear wheel that must manage the aperture. What really puzzled me is a total absence of any pin linking the aperture ring with the lens' interior, unlike the primes I opened before. So, the lever mechanism is rather hidden deeper inside the lens.



I also unscrewed three screws retaining the aperture ring, but I didn't manage to pull it off with all circular and vertical movements I tried. So I could not see how the aperture is linked to the wheel. It slides off from sides but it seemed to be held by a kind of internal protuberance at one point. And the problem is still unsolved.

So I ask for your experience. Have you any suggestions how to withdraw the aperture ring in this type of assembly, without breaking it?

And maybe if you have an experience disassembling such a zoom, how the aperture control may be fixed?