Minolta (Maxxum/Alpha) 7000 AF: Aperture issues resolved/shortcut; LCDs, aperture ring, shutter unit replaced; aperture solenoid cleaned

[Andreas Thaler]

I'm not really sure why LCDs never seem to be connected with the gold contacts directly against to the ITO traces. Regular stiff PCBs won't be flat enough and you'd be stressing the glass to try press them together, so it makes sense to use something flexible there. But here maybe the conductive bond is more about making the assembly consistent and easy.

LCDs should be controlled by voltages.

If the contacts of the circuit board are on the LCD glass, which is an insulator, no significant currents can flow.

Obviously the electric field between the plus and minus terminals of the LCD is enough to align the crystals.

But I don't really know much about LCD technology,

 

[Andreas Thaler]

@ogtronix

I have now read your complete LCD story about the Minolta 9000 AF carefully and in detail.

We both worked on the same type of display, the display units of the 7000 and 9000 appear to be identical.

I am still surprised that the display on my 7000 maintains contact without a medium. Even shaking and applying pressure to the top cover does not change this.

Just like you, I struggled with the top cover, which pressed on the circuit board with the display contacts. The result was a game of cat and mouse with the digits disappearing and reappearing.

Anyway, the topic has been discussed thoroughly and there are solutions

 

[Andreas Thaler]

Next week I'll be getting a lot of Minolta 7000 AF that I bought for a very reasonable price. All of them are declared defective. I'm curious to see what faults the cameras have and what can be done.

Otherwise I'll continue with the problem of the aperture always being open (removing the mirror box, examining the encoder mechanism, reassembling, see the thread).

I'm getting more and more excited about the 7000. Let's see where the journey takes us

 

[Andreas Thaler]

Replacing the main LCD on the top side of the camera - test run

The main LCD on the Minolta 7000 AF tends to bleed, black spots appear on the edges, but the display is usually still legible.

Since I have a spare 7000 whose main LCD is still intact, I would like to use it to replace the LCD on my work camera.

Before that, I will look at removing it from another spare 7000 as a test run.

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The main LCD on a partially dismantled 7000.

The LCD is fixed by a silver retaining clip that is locked in place by two latches.

A latch is levered out with tweezers or a small flat-head screwdriver and the clip can be removed.

Now you can see the two zebra conductive rubber strips on which the LCD rests and is electrically connected to the circuit board underneath.

The board with the LCD can be lifted …

… and the holder underneath can be removed.

The LCD and circuit board are held together by the conductive rubber strips. I carefully pulled the flexible circuit board off the LCD. The conductive rubber strips remain on the LCD.

The circuit board with the two rows of contacts for the LCD.

The LCD with the conductive rubber strips from the front and back.

Removal instructions in the Service Manual on page 147 (PDF).

 

[Andreas Thaler]

Now it is also clear that the complete LCD unit cannot be separated from the camera with a connection to the board. The plate with the LCD contacts is part of the circuit board and cannot be removed as part.

 

[Andreas Thaler]

ESD safe working on electronically controlled cameras

Newer cameras contain integrated circuits that can be sensitive to electrostatic discharges (ESD).

To avoid harmful discharges, I work with an ESD work mat and a wristband connected to it.

The mat is connected to the ground connection of a mains power socket.

This means that we are all - me, the camera and the tools on the work mat - at the same electrical potential, namely ground.

Any differences in charge are gently balanced out via an inbuilt resistor.

This means that there is no abrupt charge equalization that allows high currents to flow and can therefore damage ICs or be felt on the skin.

Working with the bracelet takes some getting used to.

You can also solder on the mat, making it a full alternative to heat-resistant silicone work mats.

 

[Andreas Thaler]

Replacing the main LCD on my work camera

After the test run was successful, it's time to replace the main LCD on my work camera, which I'm currently preparing for photography.

The display is still in good condition compared to other 7000s. So I'll keep it as a spare part after replacing it.

Here is the flawless LCD from the second spare 7000. You don't see this nice condition very often.

In contrast to the test run, here the holder for the LCD is still screwed to the camera.

This time I had to loosen both clamps of the silver retaining clip.

The good replacement display has been removed.

Now the faulty one comes out of the work 7000.

Done

The replacement LCD is on board.

First test with top cover and battery compartment attached: the LCD works.

The display is incorrect here, it should be zero. When you press on different parts of the display, the display changes.

This is obviously a contact error, which then occurs when you put the top cover back on because it presses on the LCD.

Cleaning the contacts on the board and the two conductive rubbers with isopropyl alcohol does not solve the problem. But the treatment does no harm in terms of the best possible conductivity.

Only after I put on the silver retaining clip for the display from the spare parts 7000 did the display work correctly and remain stable even after putting on the top cover.

Apparently, after removal, the clip was no longer able to hold the LCD in place evenly due to a slight deformation. This probably happened when it was pried off.

In any case, no deformation can be seen.

Mission accomplished

 

[Andreas Thaler]

A problem with the alignment of the viewfinder LCD appears

After replacing the main LCD, assembling the 7000 and testing, it becomes apparent that the LCD in the viewfinder is misaligned.

So I take the top cover off again and check the display unit. A part of the mirror box is crooked and cannot be adjusted.

The two mirrors in the display unit are firmly in place, I don't see any deviation.

The display unit is attached with these two screws. Two slots accommodate the screws and allow adjustment back and forth.

By tilting it as far as possible I can obviously compensate for the tilt of the part on the mirror box.

It's not pretty, anway it should not affect the AF or the image plane. The first test film will show if everything is OK.

I have no idea how this came about, I certainly didn't work there when I replaced the display.

The LCD is aligned straight again in the viewfinder.

For comparison, here is the position of the viewfinder display on another 7000. The LCD is positioned significantly lower and there is no distortion in the bottom right.

Since the viewfinder displays are only reflected and should not have any influence on the image, I will not look into this any further.

It was another exciting session.

Greetings from HAL 7000, the brother of HAL 9000!


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

 

[Andreas Thaler]

A test of the viewfinder image with the Minolta AF Zoom 80-200/4.5~5.6 was successful. There is no blurring to see. The first test film then shows the whole truth.

The next station before that is the Reveni Labs Camera Tester to check the shutter and exposure meter.

Then it continues with the encoder problem (see thread) on the other 7000. I have several patients here from the same family

 

[ogtronix]

Honestly that viewfinder LCD being closer to the image frame seems like a huge improvement. A complaint i'd have with these cameras is how much you've gotta squish your eye into the viewfinder to see both the frame and the LCD. Distortion be damned it looks like you've got a real unicorn!

Also man HAL9000, BFG9000... I hope Arthur C. Clarke didn't popularize that particular model number. That creep in his senility lost whatever inhibitions stopped him admitting in interviews he moved to Sri Lanka for the child prostitutes.

 

[Andreas Thaler]

Honestly that viewfinder LCD being closer to the image frame seems like a huge improvement. A complaint i'd have with these cameras is how much you've gotta squish your eye into the viewfinder to see both the frame and the LCD. Distortion be damned it looks like you've got a real unicorn!

An argument for a premium selling price on eBay or even better Etsy for this customized 7000 AF!

 

[Andreas Thaler]

I consider this optimized arrangement of the conductor tracks to be a technical work of art. The aesthetic factor is enormous.

It is worth opening such cameras just to discover something like this.

 

[ogtronix]

An argument for a premium selling price on eBay or even better Etsy for this customized 7000 AF!

If it wasn't your best working model i'd be insisting you investigate exactly how things shifted more favorably!

 

[Andreas Thaler]

If it wasn't your best working model i'd be insisting you investigate exactly how things shifted more favorably!

In this thread I'm working on several 7000s one after the other or in parallel.

This one has no faults that I've identified, except for the main LCD. But it still has to go on the camera tester.

Hopefully that doesn't matter to the reader, because that way we can discuss several faults that a single 7000 (hopefully) doesn't have together.

 

[Andreas Thaler]

@ogtronix

I'll happily leave my thread on the 9000 to you, you have more to say than I do But I will definitely continue with the 9000.

But when I'm done with the 7000 as a topic, I'll write a summary of my experiences with recommendations from my point of view. I've done that with other cameras too, not least to remember myself the most important things.

As DIYers, we actually just tinker around with other people's technical works of art with the aim of getting them up and running again. It's definitely not "factory standard".

But what else can we do?

No repair shop will take a 7000 which is for EUR/USD 35 available on the market. And Minolta is long gone.

So crazy people like us have to step in.

There is no one behind us anymore

 

[ogtronix]

I think i'm gonna save any final thoughts/ summaries on the 9000 for if I ever get around to setting up a horrible website. With the ongoing collapse of social media and old style forums like this never really resolving their systemic problem with bone headed moderators, I think websites are gonna be the only reliable thing left.

The way cheaper cameras tend to not be "worth" repairing is interesting, being sold on in various barely-functional and near-death states that only helps them continue to accrue the reputation of being unreliable or low quality - and hence remain cheap and not particularly desireable. With the opposite of course being true for cameras and camera brands with a high value, which tend to be checked and repaired to increase their value before a sale, and continue being (often mistakenly) regarded as uniquely high quality or reliable.

I'd complain about the injustice of it all, people should recognise Pentacon and Ihagee more!!, but it does mean that you can still get very good and interesting cameras for very low prices if you're willing to attempt your own repair and enjoy frustration. Having good and freely available repair resources around for cameras like these is important for that. Unfortunately right now, so many resources are incomplete, behind paywalls, or spread thin between dead and dying websites that are largely only still available thanks to archive.org. But that itself is going to continue suffering attacks for the foreseeable future and may not survive in a fully accessible manner.

Plus individual websites can just be very goofy and fun!

 

[Andreas Thaler]

I think i'm gonna save any final thoughts/ summaries on the 9000 for if I ever get around to setting up a horrible website. With the ongoing collapse of social media and old style forums like this never really resolving their systemic problem with bone headed moderators, I think websites are gonna be the only reliable thing left.

For a long time I had my own website with a blog and my photos, not about repairs at the time, but about photography in general.

Due to the stricter legal regulations in the EU on image rights and data protection, I gave up the site. I didn't want to afford in-depth legal advice, and I would have had to migrate the extensive site to a mobile-compatible format, and that was just too much work for me; I would have had to set everything up again.

Forums like PHOTRIO are neither obsolete nor are they dominated by stubborn moderators. There is space here for serious information and exchange without the abbreviations and animations that are common on social media.

The moderator team here, in particular @koraks and @MattKing, is highly committed, supportive and fair. This is one of the reasons why I like being here, and I have already been active in a few forums before.

Overall, for me it is a meeting place with committed, competent and friendly colleagues. It will be difficult for me to build such a community with my own website if I want to have a discussion there.

 

[Andreas Thaler]

Aperture stays always open - repair

Earlier in the thread I reported on a Minolta 7000 AF that did not close its aperture, regardless of the aperture value set manually or automatically.

Today I looked into the problem.

Since my diagnosis was a problem with the aperture control (encoder), I removed the mirror box to have a look.

I have already reported on the removal of the mirror box in the thread, so I will only show some impressions of today’s project here.

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The 7000 has a lot of cable connections that need to be desoldered when disassembling.

To distinguish cables of the same color, I mark them with black and white paint.

The DC/DC converter, which has its own circuit board one floor below.

The mirror box has been removed.

I compare the aperture control on the back of the front panel with the aperture control of a 7000 that has already been disassembled. I can’t see any differences, and both mechanisms move the same.

So I continue to troubleshoot.

And I find something under the bayonet.

The aperture ring, which rotates in the bayonet, has jumped off its upper right roller (red arrow). The aperture coupling is also bent (blue arrow).

For comparison, here is an intact aperture ring sitting in its roller.

 

[Andreas Thaler]

The lens has obviously been removed from the camera by force, perhaps to release a blockage, I don’t know.

After removing the bayonet, the aperture ring can be clicked into its roller.

Here is the roller that has no drive.

The two rollers opposite have gears that engage the aperture ring and drive it.

To solve this problem, I didn't have to remove the mirror box. But I didn't know that beforehand.

So now I'm going to put the 7000 back together, which I haven't done before and that is a good exercise

The mechanism for the locking pin in the bayonet that fixes the lens is a bit of a game of patience.

Succeeded

It's time to solder.

 

[Andreas Thaler]

The 7000 is assembled to the point where it can be tested for functionality.

And it works

Obviously I didn't make any mistakes when assembling it.

Now the aperture closes again to the set value.

Mission accomplished

 

[Andreas Thaler]

Conclusion

• I had actually retired this 7000 because it was very dirty and had obviously come into contact with water. So I am all the more delighted that it has been resurrected. In any case, the area under the bayonet and in the mirror box will be cleaned. I will also replace the damaged aperture ring.
• The route you take to repair the problem depends on how you diagnose it. This was a long tour because I only had to remove the bayonet to do the repair, not the mirror box. But I wanted to do that anyway to practice the process of dismantling and reassembling.
• When dismantling, I had to solve again a few puzzles that I had not mentioned earlier in the thread when it was only about removing the mirror box. It involved a soldered mounting point on the mirror box that I only found after a long search so that I could finally remove the box. And a cable that had come loose and I didn't know where it was soldered to. And again, cables that I hadn't placed properly and which kept the front cover at a distance when it was put back on.
• The two camera parts are bulky after being separated, there are cables and loose circuit board parts everywhere, it is not easy to hold these parts securely. But everything is resilient even though it does not look like it.
• At the 7000, you are tested on your ability to solder. Desoldering braid and desoldering pump should be ready in order to be able to separate circuit board connections and mounting points. The circuit boards are tight, you should have a steady hand when soldering and keep an overview. Photos for documentation and marking cables of the same color to distinguish them were helpful.
• The process of removing and installing the mirror box is complex but manageable. The service manual, SPT Journal and hopefully my report will help.
• Anyone who takes on the task will have the key to further repairs to the 7000 in their hand.

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

 

[Andreas Thaler]

This project, in which several Minolta 7000 AF cameras were involved, is now complete.

But repairs to the 7000 continue:

The Minolta 7000 AF repair marathon

I was recently able to purchase a bundle of eight Minolta 7000 AF cameras that were advertised as defective at an extremely reasonable price. The cameras arrived today and have all been through a lot. From a cracked top cover and broken light inlet cover, a shredded shutter curtain or...

www.photrio.com

Stay tuned

 

[Andreas Thaler]

Here is a little review of things that caught my attention when working on this 7000.

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Squashed cables

Since I have no indication that this 7000 has been opened before, I was surprised to see several squashed cables.

This is generally problematic because it can lead to line faults or short circuits if the insulation over the cable core is damaged.

Here I have insulated a cable with an exposed core using heat shrink tubing.

When troubleshooting, I recommend keeping an eye on the numerous cable connections.

 

[Andreas Thaler]

Easily breaking fixation point

The mirror box snaps into place on the left side of the housing using a plastic pin that breaks easily. I have glued the pin back in place using Loctite.

You should be careful when lifting out the mirror box.


Milling out a screw head with the Dremel has proven itself again

On my spare parts 7000 I was unable to remove a glued screw in the bayonet.

Milling out the screw head was possible with almost no damage to the bayonet. I used a diamond cutter on the Dremel.

The scratches caused by slipping were caused by inattention and could have been avoided.

I used the Engineer PZ-57 pliers (Nejisaurus) to unscrew the rest of the screw from the bayonet support.

 

[Andreas Thaler]

No sticky damper in the Copal shutter unit

In contrast to its big sister, the Minolta 9000 AF, there is no damper for the shutter blades in the shutter unit.

Therefore, there are no problems with sticky plastic that dirty the blades and disrupts their function.

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Here is an overview of the individual shutter parts and its control with two switching magnets (pictures of a spare parts 7000, the blades have gone out of alignment here).

In the two control curves on the right there are two parts made of soft plastic, but they are in perfect condition.


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