The Minolta 7000 AF repair marathon

[Andreas Thaler]

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 battery holders severely corroded by battery electrolyte to broken handles and a thumb rest for the shutter release held together with adhesive tape, all types of damage that have occurred through intensive use are there.

I haven't checked the eight Minoltas for functionality yet. Anyway I expect there to be errors and problems here too.

An ideal gathering to get to know the 7000 better and to try repairs. It also offers the opportunity to check the robustness of the housing against heavy use.

I will examine the cameras one by one, check for damage and faults and try to assess the chances of recovery. If a candidate cannot be repaired, it will provide spare parts. Among other things, there are three flawless main LCDs.

A real hit

I would like to take a closer look at the Minolta 7000 AF.

It is an interesting camera, a real hit on the market when it was introduced in 1985. The first SLR to offer fully integrated autofocus with numerous setting options and a modern design at the time.

But it is also exciting from a repairman's point of view, an electromechanical SLR with eight ICs, computer-controlled and still with discrete components.

Of course, it is wrapped in a layered flexible circuit board with numerous cable connections, ideal for DIY repairs.

This project will accompany me over the next few weeks, but first it will continue here:

Minolta (Maxxum/Alpha) 7000 AF: Make the aperture control functional again - repair versus shortcut; viewfinder display replaced, main LCD exchanged

With the Minolta/Maxxum/Alpha 7000 AF Minolta ushered in the autofocus era in 1985. Similar to the Minolta 9000 AF, the Minolta 7000 AF can have problems with the aperture control. No matter what aperture is set, the 7000 always creates the smallest aperture. I suspect that the contact...

www.photrio.com

Stay tuned!

 

[Andreas Thaler]

A first quick functional test showed some working, some not responding and 7000s that won't trigger.

Unfortunately, there isn't one whose aperture always closes to the smallest value, so I'm still looking for a 7000 to verify my proposed shortcut. But there's enough work to do anyway!

 

[Andreas Thaler]

First aid for battery holders heavily corroded with battery electrolyte.

A bath in Durgol descaler solution.

 

[forest bagger]

Hello Andreas,
I have a question about Durgol: Such decalcifiers are used in coffee machines and hot water makers. The acid is diluted with water and heated.
Does it work without heating?

 

[Andreas Thaler]

Hello Andreas,
I have a question about Durgol: Such decalcifiers are used in coffee machines and hot water makers. The acid is diluted with water and heated.
Does it work without heating?

I use Durgol concentrated at room temperature and it works perfectly.

 

[Andreas Thaler]

Durgol doesn't undo damage to the coating and metal, of course, but it removes the battery electrolyte and so stops corrosion.

If the contacts have lost their coating, they are more susceptible to rust.

Maybe applying conductive silver will help, but I don't know if it is suitable for high currents.

If necessary, I use the small Dremel for rework and then spray electronic cleaner onto the contacts, which forms a protective film for a while at least.

Rinse well with water and then dry with a blow-dryer to prevent rust from forming.

 

[Andreas Thaler]

I've looked through the assembly, it's going to be interesting.

The shutter on a 7000 is probably beyond repair, I have one for replacement.

The idea is also to show, that you can repair the 7000 to a large extent once you've made the trip to the mirror box and back. It's hard the first time, but the second time it's almost routine. You can get spare parts from a 7000 that you're giving up on.

It's a shame about all the good cameras that are thrown away because of what are essentially trivial faults.

 

[Andreas Thaler]

I haven't found any repair reports on the 7000 on the web, just instructions on how to get the aperture magnet working again. This was written on Usenet (now Google Groups) 25 years ago and is incomplete.

I'm surprised that no one has published anything about it since then.

The only repeated advice I've found is to buy a new, used 7000 if the old one is broken, as it's cheaper than repairing it. But if you do it yourself, it doesn't cost anything.

 

[ogtronix]

Guess that remains true; they're still pretty cheap. But I suspect an ever higher percentage of those "untested" units at the lowest prices are going to turn out to have the classic issues. I got lucky with mine but that's probably just making up for all the Praktica B200's i've bought that turned out to be broken and failed to repair. I really like their 'anti-personnel' aesthetic... but man Pentacon really rushed that particular design when trying to catch up with the Japanese manufacturers.

Still i'm excited to see the shortcut to the aperture tried in anger. Or a detailed tutorial on how to reach it the normal way through removing the mirror box. These cameras are still cheap enough that it could be a fun project with some clear steps, even if there's still a chance of failure.

 

[4season]

Part of me wants one because it's kind of iconic, but another part wonders if it's just too much crumbling 1980s plastics. I get to thinking how the rubbery bits could be used to create molds for new silicone replacements, but it could be a lot of work, and how badly do I want the camera?

 

[4season]

all the Praktica B200's i've bought that turned out to be broken and failed to repair.

What went wrong? I have that camera (branded as Jenaflex) and was able to get it working. Beneath the rather brittle plastic shell, the camera is mostly metal.

 

[Andreas Thaler]

Still i'm excited to see the shortcut to the aperture tried in anger.

Help someone who is not a native English speaker

What anger do you mean or is this a figure of speech?

 

[Andreas Thaler]

Part of me wants one because it's kind of iconic, but another part wonders if it's just too much crumbling 1980s plastics. I get to thinking how the rubbery bits could be used to create molds for new silicone replacements, but it could be a lot of work, and how badly do I want the camera?

The brittle plastic is manageable:

the handle, the battery holder BH-70S (AAA) and the thumb rest on the back panel.

The handle can be replaced or left out, the BH-70S can be swapped for the BH-70L (AA, it doesn't have a coating that falls off) and the back door can also be replaced. I have some replacement parts here that are fine.

 

[ogtronix]

Help someone who is not a native English speaker

What anger do you mean or is this a figure of speech?

Yeah it's an idiom meaning something along the lines of 'used in the real and intended situation as opposed to tests.' I think it's from a military/ weaponry euphemism. And what I mean was; can't wait to see how the aperture repair shortcut works in a real repair attempt.

What went wrong? I have that camera (branded as Jenaflex) and was able to get it working. Beneath the rather brittle plastic shell, the camera is mostly metal.

I can't quite remember... The first couple had electronic faults I couldn't solve, there was the 3rd one i'm struggling to remember anything about (I might've just gotten bored or lost and fully disassembled it), and the last one I made a real attempt with was seized almost solid with an alarming amount of cigarette smoke residue. The main issue I remember is that removing the mirror box requires removing a bunch of ancillary stuff first, and then has a bunch of stuff goes thunk out of place and it's a hell of a thing to try get it back together. The service manual I found was fairly vestigial and not much help. I was thinking I could try just get a working Jenaflex and put the cool waffle leatherette on it, I've read the Jenaflex branded ones tend to be more reliable, but i've got a complex about not feeling like I really own a device if I don't at least think I can repair it. And I don't think I could repair that series of cameras. It's like, if it might just break suddenly with no recourse then it's as if you're borrowing it from a scary dude that may suddenly demand it back at short notice.

I've got a working BX-20 that I think is pretty good too though. The problem with those is some rubber bumpers in the mechanism get brittle, fall to bits, and can get stuck in places they shouldn't be. They're nicely laid out internally though, very modular, and it's a shame they're kinda dull otherwise. I think they'd look cool repainted safety orange like one of them Genba Kantoku cameras, but you draw too much attention to yourself already just with a normal boring camera...

Secretly though i'm sulking after slightly missing the focus on nearly a whole roll of film, which is why i'm back with these funny autofocus cameras.

 

[Andreas Thaler]

And what I mean was; can't wait to see how the aperture repair shortcut works in a real repair attempt.

It's a curse, I now have eleven 7000s but I just can't find a second one that has this common error.

But the shortcut was already successful with the 7000, where I had soldered too much on the plastic housing of the aperture magnet. In the end, the aperture worked after I had removed the plastic residue from the two contact surfaces of the magnet.

It's definitely worth a try, if it doesn't work that way, the mirror box will have to be removed anyway. That's a bit of work, but it's doable, as we've seen.

 

[forest bagger]

I now have eleven 7000s but I just can't find a second one that has this common error.

Maybe this error isn't as much common as you think?
Another thought: Many 7000s items with this 'common error' were thrown away instead trying to sell them.

 

[Andreas Thaler]

Maybe this error isn't as much common as you think?

The error with the ever-small aperture is often mentioned with the 7000 on the web, and there are already instructions for fixing it in 2000:

I fixed my Minolta 7000 (aperture magnet problem)

groups.google.com

Another thought: Many 7000s items with this 'common error' were thrown away instead trying to sell them.

I'm afraid that a lot of 7000 were discarded because of this error, which is a great pity.

 

[forest bagger]

The same thing happens with many Nikon D300 and D700 who have the same problems with their aperture controls.
Nikon does nothing to repair these because there are no spare parts available, and even if they were, the labor costs would be higher than the current market value of D300 and D700.
My labor costs are also relatively high, but I still have the problematic magnets in stock.

 

[Andreas Thaler]

The same thing happens with many Nikon D300 and D700 who have the same problems with their aperture controls.
Nikon does nothing to repair these because there are no spare parts available, and even if they were, the labor costs would be higher than the current market value of D300 and D700.
My labor costs are also relatively high, but I still have the problematic magnets in stock.

What is your diagnosis of the Nikon magnet problem?

 

[forest bagger]

The permanent magnet on the core of the electromagnet, which is supposed to overcome the magnetic force of the permanent magnet only when triggered, has lost its magnetic force. As a result, the permanent magnet no longer holds the armature, so that the lever of the aperture mechanism no longer stays up.

 

[MattKing]

The permanent magnet on the core of the electromagnet, which is supposed to overcome the magnetic force of the permanent magnet only when triggered, has lost its magnetic force

Somehow, it seems that this ought to be put to music and sung

 

[forest bagger]

The Nikon magnet problem is very often to see on the Nikon D700:

 

[Andreas Thaler]

I'll pass it on here soon, with the experiences I've gathered in this completed project:

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

With the Minolta/Maxxum/Alpha 7000 AF Minolta ushered in the autofocus era in 1985. Similar to the Minolta 9000 AF, the Minolta 7000 AF can have problems with the aperture control. No matter what aperture is set, the 7000 always creates the smallest aperture. I suspect that the contact...

www.photrio.com

The aim is to make the best of the eight repair candidates, to learn about the technology of the 7000 and troubleshooting, and to get additional spare parts in any case.

All available technical documents and parts are available for this project, so there should be a good chance of success.

When dismantling the 7000 and doing repairs that have already been made, I refer to the existing threads to keep it as short and clear as possible here.

If the myth that such cameras are not suitable for DIY repairs is refuted, some defective 7000s that were previously gathering dust in the cupboard or destined for disposal should find their way back to work.


Really against all odds?

With this I would also like to contradict the master Thomas Tomosy, whom I greatly admire.

He writes about this camera class using the example of the Canon T90, which was released almost at the same time in the mid-1980s:

The Canon T-90 is a fully automatic SLR with a manual focus. It was the first camera with this rounded modern shape that is in vogue today. The Canon EOS looks similar in appearance and offers autofocus, as well. It is not recommended that you attempt to repair this camera. It is included here only to show what you’re up against when it comes to fully automatic electronic SLRs.

Thomas Tomosy, Camera Maintenance & Repair, Book 1, Buffalo: Amherst, 1999


We will see if this succeeds

 

[Andreas Thaler]

Candidate Yellow: Resurrection of an intensively used Minolta 7000 AF

The first of the eight Minolta 7000 AF from the bundle of defective cameras is given the main color yellow. It has been used intensively.

The adhesive tape around the shutter button is interesting.

The plastic falling off the handle and back door affects many 7000.

First cleaning with bellows and brush.

After attaching the battery holder BH-70L (4 x AA), the main LED shows all digits flashing. The 7000 does not respond to any inputs. After cleaning the battery contacts and removing/attaching the battery holder several times, the display is stable.

According to the technical documentation, the flashing means that the batteries are empty, which is not the case according to my measurements with the multimeter.

However, the 7000 responds to inputs only unreliably or fails completely.

The eyepiece falls out of the housing.

Removing the top cover and checking the circuit board with contacts.

At the front are the trigger contacts, behind them are the two push pads for the blue arrow keys for setting values.

Dirt on the inside of the base plate.

After closing the back door, the lock gets stuck. Despite all attempts, the back door cannot be opened again.

 

[Andreas Thaler]

Prying open the back door would probably damage the brackets on the housing. So the big Dremel has to help. For the back door I have a replacement.

I look at where I can cut open the back door without hitting the film pressure plate on the inside.

Using a steel ruler and a marker pen with a tungsten carbide tip, I mark the back door.

Cutting the back door is easy with the thin metal cutting disc.

It smokes, smells and the back door has become quite warm

Now the two parts can be removed.

Only a small amount of metal dust that can be blown away carefully not to damage the delicate shutter curtain.

Overview

Here I got into the housing with the cutting disc. But it is not serious damage, it can be repaired later with Sugru.

I compare the area with the rear housing of a disassembled 7000 from the spare parts bag.

The contacts for the automatic film feed when the back door is closed.

Now I understand why I see these contacts: the locking mechanism remained on part of the back door.

The red arrow points to the broken bracket of the back door locking mechanism on the case. This happened when the back door was removed.

The turquoise arrow points to a circlip that is stuck to the adhesive residue on the plastic cover. How did it get in there and where was its position?

I don't know it.

I remove the front panel to be able to work on the spot.

On the left is an intact back door lock from the spare parts box with bracket, on the right is the one removed from the 7000.