Minolta X-7: Artefacts on the prism; view under the top cover

[Andreas Thaler]

This beautiful Minolta X-7 has been sitting in my box of new acquisitions that I still have to check out for some time.

Today I took a look at it.

When I look into the viewfinder I see this interesting artifact. It looks like the remains of rotten foam and is reflected above the focusing screen. So I assume that this strip is on one of the sides of the prism.

I wanted to see if I could get to the prism and took off the top cover.

The steps for dismantling are essentially the same as for other Minolta X cameras and are self-explanatory.

You should be careful on the left of the main switch, the dial clicks into place over a ball on a spring. Similar to the aperture click on lenses.

Removed the top cover and desoldered five cables to the camera.

To get to the prism, I would have had to remove the flexible circuit board and do some disassembly work. Since I had no idea how the circuit board was soldered to the contacts underneath, I decided against it.

I suspect that the silver layer was removed by rotten foam on one side of the prism. Maybe I could have repaired it with conductive silver, but that wasn't worth the effort and risk of dismantling.

So I took the opportunity to look at the two ICs on the board and their labels. I'll see if I can find anything about it on the web.

Only after assembly did I check whether the self-timer works. It does, but if I tilt the camera to a certain angle, the countdown stops. This is reproducible. A contact is probably loose.

Disassemble again and troubleshoot?

No, it is not important, just like the fact that the signal tone croaks briefly when I activate the light meter. The X-7 will have to live with that in the closet

When I put on a Minolta MD 50/1.7 and checked the distance setting, I noticed that infinity was displayed at about 7 meters. It was the same with an MD 50/1.4.

As I had tried to remove the focusing screen when disassembling it earlier, I gently pressed it with the spudger and it clicked into place. Then the distance display was correct again.

We spent an interesting two hours together and I was able to get some cleaning work done.

Light seals and mirror shock absorber should be replaced. But I only do this on cameras that I use to take photos. As long as the mirror shock absorber doesn't fall off when the shutter is released and contaminates the mirror box area, nothing bad will happen.

It is pleasing that I have not seen any electrolytic capacitors in the X-7, only tantalum capacitors. This means that there are no problems to expect with damage caused by leaking electrolyte.

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Minolta X-7 at subclub.org


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[mshchem]

Fascinating! I very much appreciate your repair posts. Thanks for sharing!!!

 

[Andreas Thaler]

Fascinating! I very much appreciate your repair posts. Thanks for sharing!!!

Thanks!

I didn't repair anything this time though

 

[mshchem]

Thanks!

I didn't repair anything this time though

You have documented what is under the cover. In the future when a fellow photographer goes looking for information your posts will be a great help.
One more reason for forum members to use and support this forum.

 

[Andreas Thaler]

Considerations

• It would be nice if you could repair everything - if you weren't afraid of the effort involved. But reality sets limits.
• In this case, it would of course be possible to expose the prism in order to attempt a repair. But to do that, the circuit board has to be removed first.
• The circuit board on top is connected to the circuit board in the bottom of the camera via a conductor track on the left.
• Both boards are soldered on top of each other, and it is not clear how they make contact.
• If I unsolder them now, it will be an expedition into the unknown, and there is a high chance that I will never return.
• If I return, I can fold the circuit board over the prism away. Or I can try it from the right, the situation is similar here. Then I have to remove the cover over the prism and then I should be able to see the damaged area.
• The rotten foam has to be removed without increasing the damage. Then liquid conductive silver could cover the areas. But that is no substitute for mirroring.
• All in all, a lot of effort with an uncertain outcome. The decision not to do anything is probably the better one. The problem shouldn't get any worse, as the foam has already rotten. And when you look through the viewfinder, close to your eye, the dark stripe is hardly bothersome.
• If I had spare parts for everything, the chances would be better.

There are limits to DIY

sometimes narrower, sometimes wider. That can be pretty frustrating.

So I try not to make everything dependent on the success of a repair, and to be happy about partial successes.

For example, if a disassembly is successful, I see some of the technology and can put it back together again without any mistakes.

 

[Andreas Thaler]

You have documented what is under the cover. In the future when a fellow photographer goes looking for information your posts will be a great help.
One more reason for forum members to use and support this forum.

Thanks, then it makes sense

 

[Andreas Thaler]

This camera is probably about 40 years old.

Apart from the rotten foam, its age is only evident in the design, the state of the electronics and the fact that it is made for film.

It is scary how its owners age more noticeably