Minolta (Maxxum/Alpha) 7000 AF: Checking and adjusting

[Andreas Thaler]

After looking at how to access the shutter on the Minolta 7000 (by removing the mirror box), how to dismount it, and how to set the curtain travel times, this thread is about further checks/settings on the camera.

These are described in the Minolta Service Manual.

The nice thing about the 7000 is

that you can work with it largely without special equipment like the Minolta I/O Tester, which is not available.

This is no longer the case with the Minolta 9000 AF.

It can therefore be assumed that DIY adjustings will largely no longer be possible with the successor generation, the Dynax i series.

I therefore consider the Minolta 7000 AF from 1985 to be the last Minolta SLR that can be extensively serviced in a home workshop.

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The Minolta 7000 AF: A highly interesting SLR for DIY repairs

Anyone interested not only in the 7000 AF but also in the functionality of the first SLR with integrated AF, embedded in a comprehensive system, will be well served by this milestone in camera history.

Due to high production numbers, the 7000 is available cheaply on the used market, also for spare parts.

It still features a housing with no click fasteners (that are difficult to release) and offers an interesting combination of analog and digital technology.

Repairs are largely feasible; limitations are set by the electronics with multiple ICs/variants and the AF system, which requires the aforementioned Minolta I/O tester.

However, it is not impossible to successfully exceed these limits. ICs, indeed the entire circuitry, can be replaced with spare parts for the 7000, and alternative methods for the AF are described in the C & C Troubleshooting Guide and the SPT Journal.

This makes the 7000 AF a highly interesting SLR for DIY repairs.

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Step by step

I'll go through the individual topics here based on the Minolta Service Manual, with commentary.

We'll later work on the practical side of things.


Note

Not all of the following settings need to be made, as they are already achieved during production and experience shows that they do not change with normal use.

1. Preparation for checking/adjusting (p. 121)
2. Body back adjusting (p. 122)
3. Finder back adjusting (p. 123)
4. In-finder display position adjusting (p. 124)
5. Exposure adjusting (p. 125)
6. Manual shutter speed, X delay time checking (p. 126)
7. A/D conversion reference voltage adjusting (p. 127)
8. AE adjusting (p. 128)
9. Strobo level adjusting (p. 130)
10. AF checking/adjusting (p. 132)

Minolta Maxxum/Dynax/Alpha 7000 Service Manual : minolta : Free Download, Borrow, and Streaming : Internet Archive

The Minolta Alpha/Dynax/Maxxum 7000 service manual.

archive.org

(The page numbers refer to the reader version.)

 

[Andreas Thaler]

1. Preparation for checking/adjusting (p. 121)

To do this, the top cover is removed and the connecting cables for the flash shoe are desoldered from the circuit board.

The bottom plate is removed.

The power supply is provided via the battery holder.

Since the main switch is also gone when the top cover is removed, the corresponding switch contacts are bridged with jumper wire so that the 7000 is ON.

Now you have access to most of the board with potentiometers for adjustment and test points for measurements.

Since the ICs of the 7000 AF are susceptible to electrostatic discharges, ESD (electrostatic discharge) safe work should be carried out, see:

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-2867118

 

[Andreas Thaler]

2. Body back adjusting (p. 122) and 3. Finder back adjusting (p. 123)

This is about dimensional accuracy. For measurements and adjusting gauges and an autocollimator are required, which I don't have access to.

Since the factory settings shouldn't change here unless the camera has been subjected to force, I refer you to the service manual.

 

[Andreas Thaler]

4. In-finder display position adjusting (p. 124)

This adjusts the reflection of the LCD and the LEDs for AF and flash into the viewfinder.

To do this, loosen the two screws securing the in-finder display unit to the prism and adjust the viewfinder display according to your vision by pushing back and forth and tilting.

The goal is to position the display parallel to the lower edge of the viewfinder in a freely selectable area.

 

[Andreas Thaler]

5. Exposure adjusting (p. 125)

The AE level is set as a voltage value using a variable resistor (VR2).

This should allow the light meter to be calibrated using a camera tester.

I'll look into that soon.

 

[Andreas Thaler]

6. Manual shutter speed, X delay time checking (p. 126)

The travel times of the two vertically moving curtains (curtains travel times) are set to a target value (7.2 milliseconds) using two ratchet wheels. This changes the tension of two coil springs built into the Copal S shutter.

For this the mirror box of the 7000 AF has to be removed as well as the shutter.

If both curtains (C1, C2) move at approximately the same time, the image is evenly exposed.

The target value ensures that the shutter speed times are correctly maintained.

A shutter tester capable of displaying the curtains travel times is required for measurement (eg. Reveni Labs Camera Tester as shown on the picture).

Minolta (Maxxum/Alpha) 7000 AF: Tutorial for removing the mirror box and shutter unit, notes on assembly, adjusting the Copal S shutter

In order to access the shutter for repairs or replacement, the mirror box on the Minolta 7000 AF must be removed. The same applies to fixing problems with the aperture control or the mechanics of the mirror box. This tutorial shows the necessary steps. The basis for this is the Minolta Service...

www.photrio.com

The X delay time

is the shortest shutter speed at which the shutter is fully open.

The first curtain (opener, C1) has completely moved down, while the second curtain (closer, C2) has not yet started.

On the 7000 AF, the X delay time is 1/100 of a second.

This makes it possible to completely illuminate the image with an electronic flash, as it fires at the exact moment when neither curtain is visible.

With a faster shutter speed, at least one of the two curtains is over the image, following the principle of a focal plane shutter.

As far as I understand, the X delay time, including all other shutter speeds, is set correctly when the curtain travel times are adjusted.

The electronics of the 7000 AF control the release of the curtains at the correct time interval; I am not aware of any separate setting option.

 

[Andreas Thaler]

7. A/D conversion reference voltage adjusting

As a SLR with a clocked computer system, the 7000 AF converts analog values into digital signals for further processing.

These analog values are voltage values generated by sensors (eg. silicon measuring cells for brightness detection) or potentiometers translating a switch position.

Voltages are an analog quantity with any number of subdivisions; digital values are fixed, graduated ranges into which voltage values of a specified magnitude fall.

This conversion from analog to digital is the task of the A/D converter, which requires a fixed voltage supply. It is set as a target value via the variable resistor VR1 using a multimeter.

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See also „A/D Basics“:

A/D conversion

 

[Andreas Thaler]

8. AE adjusting (p. 128)

This adjusts the camera's exposure metering system.

The setup shown in the service manual is no longer available. Fortunately, there are new devices that can assist with this task, as the camera testers from previous decades are also unavailable.

The service manual describes the target values for the EV (exposure values) 6, 10, and 15, which are set using the variable resistor VR2 (see above 5. Exposure adjusting) for aperture priority, shutter priority, and program.

I will perform the procedure on the Reveni Labs Camera Tester and report back.

 

[Andreas Thaler]

9. Strobo level adjusting (p. 130)

This adjusts the flash duration of an electronic flash connected to the 7000 AF, which is controlled by the camera.

Time measurement from flash firing to firing-stop signaling.

Minolta Service Manual

The test setup, shown in the service manual, is also no longer available.

It may be possible to instead use a flash exposure meter and adjust the exposure using the variable resistor VR3. However, this requires developing each test shot, which is a time-consuming process.

So I'm hoping the factory settings are still valid for my 7000 AF

 

[Andreas Thaler]

10. AF checking/adjusting (p. 132)

This is about the heart of the then-revolutionary 7000 AF.

Minolta used its exclusive I/O tester to adjust the AF, which is no longer available and was presumably only operated by Minolta itself. Special AF targets are also required for testing.

But the SPT Journal puts this into perspective:

SPT Journal, 1987


An interesting alternative procedure for adjusting the AF is described by Larry Lyells in the C & C Troubleshooting Guide for the 7000 AF.

This should make it possible to adjust the AF as accurately as possible without special equipment.

I'd like to look into this soon and report on it.

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Further information on the topic „checking and adjusting“ can be found in the SPT Journal and C & C Associates Troubleshooting Guide, see below.

 

[Andreas Thaler]

Conclusion

• This information from the Minolta Service Manual, along with the other service and repair instructions listed, should make the Minolta 7000 AF repairable with a good chance of success, even in a DIY workshop.
• The 7000 AF, along with its big sister, the 9000 AF, has a reputation for being complicated constructed and difficult to repair. Based on my experience so far, I disagree.
• Given the excellent availability of spare parts and the outstanding service documentation available for the 7000 AF, almost any repair should be feasible.
• This also includes the infamous aperture magnets, which, if they fail, can simply be replaced with working ones from a spare 7000 AF.
• Tools you should have on hand for repairs: basic camera repair equipment, multimeter, oscilloscope, camera tester, ESD equipment; autocollimator, gauges, if you can find suitable ones.

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Sources

Minolta Maxxum/Dynax/Alpha 7000 Service Manual : minolta : Free Download, Borrow, and Streaming : Internet Archive

The Minolta Alpha/Dynax/Maxxum 7000 service manual.

archive.org

SPT Journal 1997

Issue dedicated to the Minolta Maxxum 7000

learncamerarepair.com

(Note: This is an edition from 1987)

C & C Associates Troubleshooting Guides - Electronic Troubleshooting the Minolta Maxxum 7000 (not available online)


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