Minolta (Maxxum/Alpha) 9000 AF: Removal of the mirrorbox/assembly, investigating the aperture issue, replacing the sticky damper in the shutter unit

[Andreas Thaler]

An SLR from 1985 that is not only beautiful but also technically innovative, but which you don't read much about:

Minolta Maxxum 9000 - Wikipedia

en.wikipedia.org

Inspired by @Paul Howell in

Impossible repairs: Who works on the latest electronic SLRs and digital cameras?

In my experience, the range of repairs reported here extends from cameras from the 19th century to around 1990. Newer devices - and thus the most advanced SLRs for film - are not included. Nikon's superlative in camera construction from 1996: The Nikon F5...

www.photrio.com

I would like to take a look at the inner workings of the 9000 and also get to the source of the well-known aperture problem.

In this case, the 9000 no longer forms aperture values correctly, see

www.9000.org - common faults

For this purpose, I have ordered a very worn Minolta 9000 at a reasonable price, which we will disassemble for this teaching project.

Stay tuned, even if it will take some time due to the large number of projects!

 

[Chan Tran]

It's kind of the first AF SLR. Others did have AF SLR before it but they changed afterward. The push button controls are the pain to use.

 

[Paul Howell]

I have 3, 2 working and one not working, the nonworking has the well know issue of not reading the aperture, I have not taken my nonworking body apart, all I tired was cleaning the contacts on the body and few lens to see if the issue is just dirty contacts. The A9000 has a lot of quirts be sure and read the manual. When loading film the meter will read 1/4000 of a second until you pass the leader to the first frame. Changing shutter speed and F stop is as noted by Chan Tran a bit of bother.

 

[Andreas Thaler]

Thank you!

I'm excited to see what happens.

 

[mrmekon]

If you find a fix for the aperture problems, I will certainly be eternally grateful. It is my favorite camera body of all time, but all three of mine are broken now.

Please, if you get to this project, take a trillion diassembly pictures for us! It's a supremely complex beast, and there is very little information available about diassembly/reassembly.

If you haven't seen it already, the best guide I've found so far is this one (in german). The service manual with parts list and exploded diagrams is also available, but it's... intense.

 

[Andreas Thaler]

If you find a fix for the aperture problems, I will certainly be eternally grateful. It is my favorite camera body of all time, but all three of mine are broken now.

Please, if you get to this project, take a trillion diassembly pictures for us! It's a supremely complex beast, and there is very little information available about diassembly/reassembly.

If you haven't seen it already, the best guide I've found so far is this one (in german). The service manual with parts list and exploded diagrams is also available, but it's... intense.

Thanks!

In any case, this will be a comprehensive photo report!

 

[Paul Howell]

What I recall is reading somewhere that the A9000 chip set is prone to crystal's forming shorting out the chip. It was an issue with 80s vintagie chips. It is thought that the U.S lost a couple of satellites due to the problem.

 

[Paul Howell]

I just dug out my non working body to check to see if by pulling the preview tab down a few would free up the aperture. Nope, the aperture is stuck on F22. Cannot advance the film. I can hear the shutter activate but lens stops down and stays stopped down. The preview tab, or switch is snappy, still might be the problem.

 

[Andreas Thaler]

There is a tutorial by Dirk Münchgesang on disassembling the Minolta 9000 and dealing with problems that we have already presented in the forum and which was recently mentioned again:

https://www.aphog.com/minolta-9000-...n-fehlern-und-kleine-verbesserung-der-kamera/

(German)

That means we already have a guideline on how to crack this nut.

I will stick to that and also to Minolta's service manual. Otherwise, we'll just see what we come across

In Dirk's pictures I see a solid construction with complex structures.

But also many attachment points for tools, which is not the case with newer cameras, at least not for classic screwdrivers.

I'm really looking forward to this journey.

---

The service manual is exemplary, everything is explained and illustrated down to the smallest detail:

Minolta Maxxum Alpha Dynax 9000 Service Troubleshooting Manual : Minolta : Free Download, Borrow, and Streaming : Internet Archive

The service manual for the Minolta Alpha/Dynax/Maxxum 9000 (or A9000/α9000) film SLR.

archive.org

 

[Paul Howell]

Looking forward to what you find. For collectors the A9000 is an odd bird. My guess is that the flack Minolta got for the XK which only in an unmotorized and a motorized body they did not include an integrated motor drive. The choice was manual wind, a motor winder and a true motor drive that takes 12 AA batteries. As far as I know it was the only pro level AF body without integrated motor drive. I just put a roll of film in one of my working bodies and loaded up the winder with a mere 4 AAs. I did shoot a roll with the motor drive, the full flash set up, 2 flashes a main and fill with a AA battery pack, in total, camera, motor drive and flash setup takes 32 AA. The bulk film back takes 100 feet.

 

[Andreas Thaler]

On page 1 of the Minolta Service Manual for the 9000 we are shown the scope for action, which I think is very useful to avoid disappointment:

 

[Andreas Thaler]

If we want to get to the shutter, which can obviously have problems with contamination, we will have to remove the mirror box, which is therefore not recommended.

Or this note refers to the mirror box, which is part of the front panel and can be removed together with it.

I don't know yet.

The aperture control should be on the mirror box. That should be the location of the problems with closing the aperture.

We'll see, my candidate is still in the mail and I'll look through the service manual over the weekend.

Unfortunately I haven't found any article about the 9000 in my SPT Journal issues, which would be very helpful. Maybe I'll discover something after all.

The above post by Dirk is very helpful, even if it is not a complete tutorial.

In any case, we will see interesting things, that much is certain

 

[Andreas Thaler]

For collectors the A9000 is an odd bird.

This is certainly also due to the fact that the plastic leather covering becomes sticky. This doesn't look good, nor is it pleasant to hold.

We will also deal with this in this thread.

 

[Andreas Thaler]

For the 9000 there is the beautiful and powerful Motor Drive MD-90, which I own.

We'll at least take a look at it from the outside.

www.9000.org - motor winder

 

[Andreas Thaler]

The reference site:

https://www.9000.org

 

[Paul Howell]

Need 12 AA batteries to power it up. Make sure set the counter on the motor drive to match the counter on the A9000, if you have 36 exposure roll but the drive is set for 24 the camera will stop at 24 until the counters match.

 

[Andreas Thaler]

I also have the Program Back Super 90 with features that are still incredible today:

www.9000.org - backs

 

[Paul Howell]

I dont have the program back, just the bulk film back which I have used just one time.

 

[Andreas Thaler]

I dont have the program back, just the bulk film back which I have used just one time.

If you ever want to part with it please send me a PM

 

[Andreas Thaler]

Assessment of the chance of success after reviewing all available documents

Following Dirk's post, the aim is

• to dismantle the front panel with the mirror box,
• then you get to the shutter, which is also removed for cleaning if it is dirty, and you also get to
• the aperture mechanism and the magnets, which you can study and clean as well as possible.

This is reminiscent of the Nikon F4, which is constructed in a similar way.

The biggest challenge beforehand will probably be dismantling the flexible circuit board.

Dirk has given tips on what to look out for. The Minolta Service Manual is also very helpful.

I think we can manage it if we proceed carefully, slowly and systematically and document every step for the assembly.

 

[Andreas Thaler]

Minolta 9000 brochure:

http://www.massimoscottinelweb.com/Immagini%20ridotte%20per%20SITO%20web/Minolta%20Cataloghi%20e%20Pieghevoli%20in%20pdf/Minolta%209000%20AF%20-%209000%20507E-A1.pdf

Owner’s manual:

https://www.minolta.suaudeau.eu/ressources_iconographiques/Minolta_9000.pdf

 

[Andreas Thaler]

According to the service manual, the Minolta 9000 has a photointerrupter built in that is responsible for AF and aperture control, similar to the Nikon F4.

A rotating disk with openings interrupts a beam of light, generating electrical signals.

In the F4, which also has a common aperture problem, the cause is a lack of lubrication of the disk.

Perhaps the 9000 has the same problem.

We'll see soon.

 

[Andreas Thaler]

Checking for the aperture issue

I currently have four Minolta (Maxxum) 9000s here, which I have checked for the aperture issue.

The result: 3 x OK, 1 x defective

Great, now we have a candidate to disassemble and repair


Check procedure

The 9000 is wound up, set to MANUAL mode and the largest aperture is set on the lens (= smallest aperture number).

The stop down lever is set to the first of three positions.

You should only hear a click and see no diaphragm movement.

In position two the aperture should close to the smallest value.

Position three sets the aperture back to its largest opening.

See also:

www.9000.org - common faults

On the 9000 with a defective aperture control, there is neither a click nor does the aperture move.


Cleaning the leatherette

On all 9000 here, the plastic parts on the handle and back door are covered with a white coating and are sticky.

The coating can be easily removed with isopropyl alcohol on a cloth.

This also eliminates the stickiness


No sticky shutter

The shutters on all four 9000s work. There is no dirt visible on the rear shutter curtain.

I have not carried out any further checks.

---

The repair project

I will disassemble the defective 9000 to get to the aperture control by removing the front panel.

There I will look for the photointerrupter mentioned above and check whether it can be freely turned.

I will report on this live in steps.

We will start tomorrow Tuesday (CET).

Stay tuned!


+++

All information provided without guarantee and use at your own risk.

 

[Andreas Thaler]

Removal of the top cover

On page 30 (PDF) in the Minolta Service Manual there is an exploded view showing all the parts and screws that have to be removed to remove the top cover.

Some tips from Dirk were also helpful.

---

There are obviously two pins missing on the rotary ring for setting the exposure metering modes, which the cap of the rewind crank engages in to move it. The switch also turns beyond the positions.

I'll look at that later.

Two screws next to the eyepiece.

A screw on the side above the handle that holds the two AA batteries.

There is a screw under the metal cover plate on the knob for adjusting the diopter correction.

A screw holds the plastic cover over the metal winding lever.

The main switch can be removed after unscrewing the retaining ring.

There is also a screw under the labeled and glued plastic plate.

 

[Andreas Thaler]

The fold-out rewind crank is fixed by a retaining clip.

A retaining ring and a screw hold the rewind axle assembly with fork.

After disassembly.

When I used a screwdriver as a lever, a piece of the brittle plastic covering of the grip broke off. I then exposed a part to see the structure underneath.

The spot can be closed later with Sugru.

A screw in the battery compartment still holds the top cover.

Now the top cover can be removed.

Two cables connect the top cover to the housing and are desoldered.