Minolta (Maxxum/Alpha) 9000 AF: Tutorial for removing the mirror box, notes on assembly, cleaning/adjusting the Copal S shutter

In order to access the shutter for repairs or replacement, the mirror box on the Minolta 9000 AF must be removed. The same applies to fixing problems with the aperture control or the mechanics of the mirror box.

This tutorial provides information with direct reference to the Minolta Service Manual for the Minolta (Maxxum/Alpha) 9000 AF.


Notes:

• Since the Minolta service manual for the 9000 AF shows all the steps including assembly clearly and understandably, I will limit myself here to some photos and notes on the individual stages of disassembly.
• I strongly recommend that you first read the instructions in the service manual in order to understand the process and adapt the implementation to your own skills.
• Prerequisites for the work are a confident handling of precision mechanics and electronics and solid soldering skills. Some cables have to be soldered in inaccessible places, and separating and assembling the housing and mirror box in particular requires sensitivity and care. If possible, the process should be practiced on a 9000 AF for spare parts.
• Be aware that the service manual may not cover all circuit board versions and modifications.
• Adjustments are not necessary after installing and removing the mirror box, at least I have not found any information about this in the service manual.
• The ICs of the 9000 AF are sensitive to electrostatic discharge. ESD protection should therefore be used.
• All information provided without guarantee and use at your own risk.

The following page references refer to the PDF version:



Removal of top cover and housing covers (p. 30)



The order of disassembly is not fixed and is shown in the illustration.


Overview of the soldering work (p. 114)



The instructions in the service manual refer to this page


Mirror box assembly removing (p. 120)



Detailed step-by-step instructions with illustrations


Mirror box assembly installing (p. 124)



Detailed step-by-step instructions with illustrations

Not all steps are listed here, they are given in the disassembly section, so refer there.

The rewind crank can be pulled out after removing the fork for the film cartridge.

This also eliminates the function for opening the back door, which should therefore be removed.

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Opening the locked back door with the rewind crank removed





Pry off the glued cover.




Push this lever up against the spring until the backdoor springs open.

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The small plate is glued on. Remove it using the flat blade of a small screwdriver, for example.




This label is also glued on and can be carefully pried off.

The screw underneath fixes an electronic contact between the top cover and the circuit board and must not be lost.




One of the retaining screws for the top cover is located in the battery compartment.




The eyepiece has a protective glass that is loose after removing the top cover.






The top cover is connected to the circuit board with two cables and is desoldered.

Bottom cover, three screws.






The side covers are glued on and can be carefully pried off.




The focus selector switch on the side of the front cover is set to „AF“ before removing the cover.




Overview

The dial is attached with this clip that slides on. It hooks onto a pin.




The spring under the dial hooks into the case here.




The spring must be attached the right way round as it has differently shaped ends.




Be careful with the delicate wipers, they bend easily.




Such solder joints can be easily separated using desoldering braid. Flux and brief, strong heat from a wide soldering tip help with this.




The counter base plate is a precision mechanics masterpiece.

To get to the flex pressure, I unscrewed the LCD unit, folded it away and secured it with adhesive tape.

Be careful not to overload the flexible circuit board and break it.




The circuit boards are fixed on two pins.




The plate underneath must be carefully pulled out from under the circuit boards.

A game of skill.




The switch for the battery holder.






It is attached with a screw and nut.




The screw is located in the battery compartment and does not need to be loosened.






This small pin must not be lost. It sits loosely under the end of the switch.




When the battery holder is inserted, it pushes the pin up against the switch and opens it.




Overview

The shield on the in-finder block is glued and bends easily, so remove carefully.




For the following desoldering work, I fixed the unscrewed in-finder block with adhesive tape so that it would not be in the way.




Desoldering the second of two board connections with desoldering braid.






Carefully prying off a glued plastic plate.

Removing the large connector plate that fixes three layered circuit boards. It is equipped with hard rubber pads on the underside.




Document all cable positions for later assembly.




Among others this light grey cable is mentioned in the desoldering instructions. It runs under the upper circuit board and is difficult to find.






The eyepiece with shutter is attached to the housing with two screws and is lifted out.

Another circuit board connection needs to be desoldered at the bottom of the camera. It is fixed with three soldering points; it helps to desolder the surrounding cables first.

I also saw a second version of this board with different cable positions.




According to the service manual, the mirror charge lever should be removed before removing the mirror box.

I couldn't do that because I couldn't find the right position to pull it out.






Instead, I removed these plain bearings, in order to be able to push the rod above it a little to the side.

When I later lifted the mirror box, the lever came out easily.

Before the circuit board underneath can be removed, the tripod plate must be unscrewed. This is not mentioned in the service manual. The screws are secured with adhesive.








The circuit board is fixed with two adhesive strips.

Make sure that the trim pots are not adjusted when removing it.




Done

Before and when lifting the mirror box out of the housing, make sure that no cable has been overlooked when desoldering and that the circuit board connections on the bottom and both sides of the housing are free.

Also pay attention to the charge lever if it is still installed.

If everything fits, the mirror box can be lifted out without any effort.










Overview mirror box …








… and housing.

Now various repairs and service can be carried out.

For example, removing the sticky damper from the shutter unit or replacing it, cleaning/replacing the aperture magnet, removing blockages in the mechanics and more.

It is important not to misadjust the AF control on the underside of the mirror box, as correction is not possible.

The factory settings in the camera should not be changed at all, unless there is a legitimate reason to do so.

See our repair thread for the 9000 AF:

When reassembling, the mechanics of the mirror box and shutter must be tensioned, see the service manual.

Reassembly is then carried out in reverse order.

There are instructions for this in the service manual, but they are incomplete. Therefore, consult the disassembly instructions.

Good luck and success with your work!


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

Cleaning the Copal S shutter on the Minolta 9000 AF, adjusting the curtain speeds

Once the mirror box is removed, access to the shutter unit is clear.

To replace/clean it the shutter unit must be removed from the back of the 9000 AF. This is easy; only screws have to be losened.

The 9000 AF's shutter contains a damper that rots and becomes sticky over the decades. This causes the shutter to no longer function reliably and requires cleaning.

To adjust the curtains, you need a camera tester that can measure the curtains travel times. For the Minolta 9000 AF this value is unknown to me. I suggest to try it with 3.3 milliseconds for each curtain. I use the Reveni Labs Camera Tester.

Adjusting the curtain travel times should be possible even when the shutter is installed.

Detailed information can be found here:




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