Minolta XD7 (XD, XD11): Cleaning the pneumatic mirror shock absorber

The Minolta XD7 (XD, XD11) has a pneumatic mirror shock absorber built in, which consists of an air cylinder, air piston and a spiral spring.

The proper functioning of the shock absorber can be impaired by dirt in the cylinder, which results in a delayed release of the triggering process.

The mirror shock absorber can be removed without much effort for cleaning and lubrication.

However, as I found out, the subsequent reassembly is not that easy.

The removal and cleaning of the mirror shock absorber is shown in this video (German):




Let's look at the process.

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Removal of the pneumatic mirror shock absorber

I am working on my practice XD7, from which I had already removed the aperture simulator ring as a spare part, see









The aperture simulator ring around the bayonet is missing here, see above.






The spring for the aperture simulator ring, which is attached to a hook that is obviously not an original part.

The original hook is likely to be loose without spring tension after having removed the ring. It should therefore be removed so that it cannot fall into the interior of the camera (see video).






Two plastic tabs for securing the bayonet cover.

Therefore, the base plate must be removed so that the bayonet cover can be dismounted.






Position of this intermediate ring.






The cover plate of the pneumatic mirror shock absorber is held in place by an adhesive tape.

Here the adhesive is already in transition to sticky grease.




The cover plate can now be removed.




A plastic film for sealing flattened here.




The air cylinder with recessed piston in its bottom.

The piston presses against a clutch lever below through the built-in spiral spring.

Cocking the shutter, bulb mode is set.




The shutter is released, the mirror is flipped up. The clutch lever folds down, followed by the piston.




The shutter is closed again and the mirror is folded down. The piston is back in the air cylinder.




Two screws hold the cylinder.




After loosening the screws, the cylinder can be removed.

Be careful of the spring so that it does not jump away.


Cleaning



The individual parts of the pneumatic mirror shock absorber.

Top down:

• air cylinder, screws
• spiral spring
• piston

Clean the inside of the cylinder and the piston with isopropyl alcohol. Dry with the bellows before reassembly.

Moisture can make it impossible to remove the piston from the cylinder if you test without the spring.

The piston can then be lubricated with a very small amount of light oil. I am undecided here, as oil may inhibit the flow.


Assembly





There are recesses in the cylinder (top) and piston (bottom) into which the ends of the spiral spring can snap. The longer end goes into the piston.




The chamber for the mirror shock absorber, on its bottom the clutch lever for the mirror mechanism.




The narrower side at the top of the cylinder points away from the camera.




Be careful that this spring does not come loose and fall into the interior of the camera.




I fix the plastic film with an adhesive strip so that it does not interfere with the installation of the cylinder.

I let the piston, which is pushed away by the spring in the cylinder, snap against the clutch lever. Then the cylinder can be inserted into the chamber.




Done




Fasten with the two screws.

There is a sealed adjustment screw on the cylinder that is not inserted into the opening above it in the camera housing.




Test in bulb mode, the piston moves, the triggering process is quick as it should be.




The cover plate is inserted …




… and fixed again with the adhesive strip.




When the adhesive strip was removed, the plastic film came off with it.

No drama.




The greasy adhesive strip contaminates tools and gloves.




Our test candidate and the parts that still need to be installed.

Conclusion

• Removing the mirror shock absorber is easy, but installing it with the spring-driven piston is a bit tricky.
• It took me some time to understand that the adjustment screw on top of the air cylinder is not placed in the opening above it.
• I cannot answer whether you should oil the piston or not, but Larry Lyells recommends it in The Camera Craftsman (see below, p. 37) and he is of course always right

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Technical Information


Here the technology of the Minolta XD11 (XD7, XD) is described in detail by Larry Lyells.