Repairing unreliable aperture ring on Minolta Maxxum 9000

[mrmekon]

I recently picked up a Maxxum 9000, unaware of their history of aperture ring problems, and my "fully functional" new camera turns out to be only semi-functional. It's quite an annoying problem: the aperture stops down perfectly reliably as long as you shoot continuously. If I pause for longer than about 10 seconds, the next frame will always shoot wide open. Likewise, it always shoots wide-open after turning it on or attaching a lens. Using the shutter unsticks it, though, so after one wide open frame it starts stopping down correctly until the next pause/power cycle/lens swap. When it is working, it works 100% reliably, which I consider quite odd. I can toggle the DoF preview on and off a thousand times in a row, but pause for 10 seconds and it sticks until the next shutter release.

I found quite a few people complaining about similar issues, but very few discussing how to actually fix it. Most references are on long-dead forums, where they say "send it to your local Minolta repair shop"... but it's 2022, and my closest Minolta repair shop is somewhere on the other side of a time machine.

So, maybe this is a long shot, but does anybody have any experience with fixing this issue? I found two very old forum posts saying it can be fixed by "merely" cleaning a magnet, though that magnet is very deep inside the camera. I would be willing to give it a try, but would like a little bit more confidence that just cleaning it is likely to work. It doesn't seem like there is any way to test it while everything is open, and it would be a shame to spend several hours tearing it apart and rebuilding if that's unlikely to fix it.

Thanks!

 

[BobD]

Aperture ring on a Maxxum? Do you mean the aperture lever on the rear of the lens or in the camera body?

If you have a lens with an oily, sluggish diaphragm, it can behave as you describe. The cure is to clean the diaphragm blades.

 

[mrmekon]

It's definitely the ring in the camera body. I have plenty of A-mount lenses and two other Minolta bodies, and everything works except this 9000. This happens with any lens mounted.

The aperture ring in the body is supposedly held in place by a fixed permanent magnet, and modulated by an electromagnet when the shutter releases or the DoF preview lever is pulled. I have seen claims that old grease/oil migrates to around the fixed magnet and causes this, but unclear if that claim is true.

The electromagnet clearly hasn't completely failed, since it works reliably when used continuously. That could indicate that there is some sticky old separated oil in there somewhere, and it only works while the oil is warmed up a bit by friction? But power cycling the camera immediately causes a failure, so maybe not.

 

[John Koehrer]

sorta kinda useful(less?) information here but Minolta has had sticky magnet problems in the past. Earlier
X700 had a common release magnet failure so why not this one?

 

[mrmekon]

Yes, I think this same problem occurs for several models. Has anyone successfully fixed any of them?

 

[Paul Howell]

Nope, I have 3 9000s, one is totally inoperative, aperture is fixed at smallest F stop, F16 to 22 depending on the lens. One body as you described, and one still fully functioning. Checked with a few repair tech, no one will one work on the 9000, lack of parts, hard to find shop manuals. I use my 800si, 9xi and 9, only the 9000 on occasion. With fresh batteries it will shoot a tad faster than the 9.

 

[Andreas Thaler]

Have a look at

Post in thread 'The Minolta 7000 AF repair marathon'
https://www.photrio.com/forum/threads/the-minolta-7000-af-repair-marathon.211737/post-2872483

Post in thread 'Minolta (Maxxum/Alpha) 7000 AF: Aperture issues resolved/shortcut; LCDs, aperture ring, shutter unit replaced; aperture solenoid cleaned'
https://www.photrio.com/forum/threa...aperture-solenoid-cleaned.211422/post-2867930

The aperture rings of the two sister cameras, the Minolta 7000 AF and 9000 AF, were supposed to be identical.

In each case with the 7000, there was a mechanical defect on the ring, which could easily be repaired from the outside or by exchange.