Strip down and attempted repair of a copal-X shutter – part 1

I acquired a Rank Mamiya Auto-Lux 35 Fixed lens SLR a few days ago and although I’m pretty sure it was working when I first received it the shutter and aperture stopped functioning pretty soon after I first tried it. So I thought I’d have a go at finding out what I needed to do to fix it and recorded it in case anyone else ever needs (well wants really – I can’t imagine anyone would need to repair one of these cameras) to do the same.

As it happens I haven’t been able to get to the bottom of the problem yet, but I’m publishing this record so I can remember the steps I took and the reassembly information ready for when I next get the opportunity to work on it. Just for the record this camera is fitted with a copal-X shutter / aperture assembly.

The symptoms of the fault were that the shutter only properly tripped at 1/500 sec. At any other speed the shutter would act as if it was in B mode and remain open as the shutter release was pressed. Also, as I was looking through the camera to see if the aperture was stopped down I saw one of the shutter blades permanently stuck out into the centre of the lens. The shutter sounded like it might be a lubrication problem, but the aperture blades were obviously out of alignment and would need some TLC.

Apologies for the quality of the pictures which follow – these were taken with my Ricoh GXR as I carried out the work.

The first thing I did was to take off the bottom camera plate by removing the two screws which held it in place. Sometimes it’s possible to apply some lubrication here and work in into the mechanism, but once the bottom was off and I’d applied a bit of thin oil it was obviously not going to help so I carried on with more dismantling.

The next item to remove was the top cover which was a question of removing the wind on lever by unscrewing the centre with a pair of tweezers in the two small holes and pulling it off. The rewind crank was removed by unscrewing the top from the shaft in the usual way (hold the rewind crank inside the camera with a screwdriver through the splines and turn the crank). Then I removed the two small screws in the sides of the top plate and it came away. Be careful because the shutter button drops out as you lift it up.

Then I peeled back the cloth trim from the front of the camera to reveal 4 screws which held the shutter assembly in the camera. I removed these and found the lever at the bottom of the camera which cocks the shutter also needs to be disconnected by removing a circlip. Once these were all out, the whole of the middle of the camera came out of the camera body and I could look at what the problem with the shutter might be.

I set the focus to infinity and removed the three screws round the front of the lens which allowed the front to pull off. With that removed I could unscrew the lens front element from the camera which got me down to a plate covering the shutter assembly. I could see three small screws holding this plate in place so I removed them as well, but the plate wouldn’t pass over the ring in front of the plate, so I used a lens spanner to remove that ring first.

That ring was in fact the middle element of the lens and with that removed I could see a spring loaded cog assembly which adjusts the film speed pot. It looked like on this camera that arrangement wasn’t working and that seemed to be because the bracket that the cog sits in at the back of the shutter assembly needs to be slightly bent so the end of the rod is supported. I made a note of that so I could fix it as I reassembled the camera.

I thought that I must be close to the aperture now and there seemed to be only one screw to undo which would get me access so I tried removing that screw (in the middle of the lens assembly) next. What I found however was that it wouldn’t unscrew. It turned, but didn’t unscrew itself out of the body of the lens. It was at this point, as I was turning the camera over that the loose aperture blade fell out of the front of the lens! Interestingly, once the aperture blade was out the aperture would then stop down when the shutter was released, so the loose blade must have been the object fouling the aperture mechanism, although the shutter was still not firing correctly.

After playing about with the screw I suddenly realized that one side of the head of the screw was flat and I that the purpose of the screw was to act as a locking screw for a brass washer in the middle of the lens assembly. Sure enough, once I turned the screw so the brass ring could turn I could undo it. With that brass ring out I could remove the plate on the front of the lens assembly, and pull the film speed cog out of the camera.

This revealed the actual shutter mechanism which I examined to try to find what is causing the issue but at the moment I can’t work out the problem. That will be my ‘camera repair’ task for next weekend.


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