Minolta X-700: A renovation project

koraks · Jan 23, 2024

Andreas Thaler said:
The question is whether the signal from the sensor - I assume it is a photodiode - needs to be amplified for this.

If it's low impedance enough to be recorded by a phone, it's definitely low impedance enough to be viewed with a scope without any interfacing. And indeed, this has been done; I think there's a thread with some pics from a few weeks ago where people were troubleshooting this thing.

KerrKid · Jan 23, 2024

This writeup blows my mind. I'm not worthy. I think I'm handy, but Andreas is on another planet.

Andreas, thank you so much for this renovation project. I learned a lot.

tjwspm · Jan 23, 2024

I think it would be nice if I could always see the entire curve, like the 1/1000 s measurement. Then I could easily measure the duration of the full opening on the time axis.

Andreas Thaler · Jan 23, 2024

KerrKid said:
This writeup blows my mind. I'm not worthy. I think I'm handy, but Andreas is on another planet.

Andreas, thank you so much for this renovation project. I learned a lot.

Thank you!

I just try to work precisely and consistently and learn every time. I still don't understand 99 % of the X-700.

Andreas Thaler · Jan 23, 2024

tjwspm said:
I think it would be nice if I could always see the entire curve, like the 1/1000 s measurement. Then I could easily measure the duration of the full opening on the time axis.

The instructions for the Photoplug state that only the beginning and end of the curve are relevant for measurement:

ANALYZE THE MEASUREMENT
The App displays a waveform with two peaks.

Zoom into the signal (two finger pinch) to maximize the signal to the full screen width.

Select the target shutter (the speed you set on your camera) on the bottom left corner.

Use the two blue sliders to measure the distance between the two peaks. Measure from the start of the first to the start of the second peak.

Filmomat — PhotoPlug

www.filmomat.eu

Andreas Thaler · Jan 23, 2024

forest bagger said:
Great work, Andreas, as always!

Thank you!

I have learned a lot from you over the years, in the German photo forums, via correspondence, where you gave me friendly advice, and through your professional repairs on my devices.

A long friendship that I am very happy about.

Andreas Thaler · Jan 23, 2024

Andreas Thaler said:
View attachment 360596

This is about adjusting the coupling for the aperture simulator (source: Minolta Service Manual for the X-700).

At this point I had removed parts so that I could clean them. Assembly went without any problems, but is the adjustment correct now? I'll check that out.

I must not forget to check this.

I just went through the previous report again and saw how the contacts are adjusted there.

Since this is also my repair log for the project, I'm making this note.

tjwspm · Jan 23, 2024

Andreas Thaler said:
The instructions for the Photoplug state that only the beginning and end of the curve are relevant for measurement:

I understand. Thanks for the tip.

Andreas Thaler · Jan 24, 2024

The finish line is in sight!

What's still missing is repainting the areas on the top cover that were repaired with Sugru, checking whether everything is OK, assembling and testing for functionality.

Let‘s start!

Repainting

The areas repaired with Sugru have hardened after 24 hours.

I use fine-grained sandpaper to smooth the areas.

Sugru can be easily scraped off the copper areas with the Spudger.

There shouldn't be any Sugru there, because I can repaint these areas directly.

Sanding

Paint over with black gloss paint and let dry.

Check the clutch for the aperture simulation

Here I wanted to check whether the contact plate is seated correctly.

Everything is ok, there is only one position because I only loosened the left screw (red) but not the second one to fix it (green).

Check before assembly

Before assembling, I check the camera again to make sure everything is seated correctly.

There is still rust on both screws.

The switch for the self-timer and storage of the exposure measurement value can be moved in both directions, as it should be.

The screws get a bath in Durgol.

In the meantime, I'm assembling the ASA/Exposure Compensation Wheel, which I had disassembled to clean.

The parts waiting to be assembled.

Andreas Thaler · Jan 24, 2024

Both screws are rinsed in Aqua Purificata and then quickly dried with the Dremel Versatip butane gas burner on a heat-resistant silicone mat.

An attached hot air nozzle reduces the heat and can be controlled better than when working with an open flame.

This looks good now.

Same procedure for other screws with rust.

Assembly

The casing for the bayonet is put on for testing, without the button for the lens release and stop down button inserted.

Now with the buttons and fixed with its two screws.

The spring and screw on the self-timer/measurement lock button are slightly rusty.

I apply Ballistol universal oil, which dissolves and protects rust.

The right part of the cover is assembled.

Likewise the one on the left.

These two parts of the leatherette are self-adhesive. Still, after around 40 years!

The rust-free screws are now ready for installation.

The base plate is screwed on.

I put three marking points for three installed blue tantalum capacitors. So I don't need to check this X-700 later for expired electrolytic capacitors.

The piezo element for sound generation is located in the top cover.

Andreas Thaler · Jan 24, 2024

The cables from the top cover are soldered back to the board.

A cable that couldn't be soldered securely kept me busy.

But now everything is in place.

The parts under the ASA/Exposure Compensation Wheel are attached.

The remains of the milled screw next to the eyepiece prevent me from putting the top cover on.

I solve this with the Dremel with a tungsten carbide cutter.

Some of the plastic underneath came off.

This is not nice indeed, anyway this spot will no longer be visible

The top cover can now be put on.

The winding lever got a new spring (left) because the old one was weak. But it can no longer be locked in the unfolded position.

It's annoying, but I won't bother with it now.

Maybe I will check this later along with removing and cleaning the focusing screen.

However, the screen is only slightly dirty and I don't want to remove it if not required because it is very sensitive to scratches.

Here my bag of original X-700 spare parts saved me once again.

The ASA/Exposure Compensation Wheel is mounted.

The screw for attaching the cover to the side is missing.

Another screw is unscrewed from an assembled X-700 for reference.

A replacement is quickly found in stock.

Rewind crank and back door are installed.

Functional test

Everything works as it should

Shutter speeds are now displayed in the viewfinder without jumping when the aperture ring is rotated.
All switches and buttons can be operated without any problems.
The transparent plastic viewing windows are clear, and the displays underneath are now perfectly legible.
The camera fires.
I had already tested the shutter speeds yesterday with the Photoplug.
The self-timer and storage of the exposure measurement value work, the LED also lights up and the signal tones are there.
ASA setting and exposure compensation work.

I'm relieved

Andreas Thaler · Jan 24, 2024

I attach the remaining third part of the leatherette to the handle with Pliobond.

The exposure metering is also OK.

The measured values agree with my Nikon F3/T

On the catwalk

An X-700 that still shows that she has been used intensively sits on the table, clean and ready for use.

It looks quite different now than it did at the start of the project.

Replacing the light seals and mirror shock absorber is a follow up project.

Anyway, the next film is hers!

+++

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

Andreas Thaler · Jan 24, 2024

Thank you for reading and all comments!

This project was fun!

Now I'll take a break and then I'll finally continue with the R3 MOT owned by @miha

Stay tuned!

KerrKid · Jan 24, 2024

I noticed you used Ballistol. Excellent product that a lot of people still don't know about.

I like how you listed the tools and chemicals you used like Durgol, Pliobond, and the Ballistol. I looked up Durgol and found that it is sulfamic acid. Also the Spudgers. Those are nice. I also noted the Vessel JIS tools.

Of course, the camera was still an X-700 when you got done. Turning it into an X-570 would have been nice.

Andreas Thaler · Jan 24, 2024

KerrKid said:
Of course, the camera was still an X-700 when you got done. Turning it into an X-570 would have been nice.

You mean because of the tracking display in the viewfinder for manual exposure adjustment?

That would be a nice electronics project, but I'm afraid no one can do it.

You would have to deal with the complex circuit in detail and know what the four ICs are talking to each other, that is not documented.

Andreas Thaler · Jan 24, 2024

KerrKid said:
I noticed you used Ballistol. Excellent product that a lot of people still don't know about.

Yes, everyone who owns a gun probably knows Ballistol

Andreas Thaler · Jan 24, 2024

KerrKid said:
I like how you listed the tools and chemicals you used like Durgol, Pliobond, and the Ballistol. I looked up Durgol and found that it is sulfamic acid. Also the Spudgers. Those are nice. I also noted the Vessel JIS tools.

Yes, it took a while to get my things together. I am confident in what I use here, so I recommend it.

But, as I said, I don't make any money from it

Andreas Thaler · Jan 24, 2024

Now, of course, I'm interested in whether the system accessories on this X-700 work, especially the Minolta Auto Winder G.

But I don't want to exaggerate, I'm glad that this worthy example with history works so far.

The Minolta winders will also be on the workbench this year.

I had some Auto Winder G's that surprisingly suddenly stopped working.

I stupidly gave them away at that time, but I got some repair candidates for the purpose of studying

miha · Jan 24, 2024

Andreas Thaler said:
Thank you for reading and all comments!

This project was fun!

Now I'll take a break and then I'll finally continue with the R3 MOT owned by @miha

Stay tuned!

Hopefully a much easier fix I'm looking forward to

KerrKid · Jan 24, 2024

I still think a Maxxum 7 base plate aperture issue would make an interesting repair since it is rumored to be a very difficult.

Andreas Thaler · Jan 24, 2024

KerrKid said:
I still think a Maxxum 7 base plate aperture issue would make an interesting repair since it is rumored to be a very difficult.

Who volunteers?

Andreas Thaler · Jan 24, 2024

KerrKid said:
I still think a Maxxum 7 base plate aperture issue would make an interesting repair since it is rumored to be a very difficult.

Dirk Münchgesang in the German APHOG took a look at the inside of the Minolta 9000.

APHOG: Troubleshooting the Minolta 9000

Repair reports for the Minolta 9000 are rare. It is all the more gratifying when you find a report that addresses four problems at once. In his report on the German APHOG, Dirk Münchgesang reports on shutter cleaning, fixing a known problem with the aperture, contact errors and how to get more...

www.photrio.com

Andreas Thaler · Jan 24, 2024

I think a lot can be done, ultimately it's all about disassembling and reassembling. Provided you have a spare part or can repair the broken one.

This requires energy, endurance, time, motivation and pedantic documentation.

forest bagger · Jan 25, 2024

Again THANK YOU, Andreas, for this report!

I have but a question: Why don't you remove this PASSED badge and clean the place where it was, as you cleaned the rest of the top cover?

Andreas Thaler · Jan 25, 2024

Mini tutorial: Removing and installing the focusing screen

Since I wanted to get rid of the dust and dirt underneath the prism and on the top of the focusing screen, I looked at how to go about it.

These are the instructions for removing and installing the focusing screen in the Minolta service manual for the X-700.

I understood the fastening principle, but couldn't handle the recommended tweezers.

I decided to try the plastic Spudger, which now accompanies me on every project because it can be used universally.

Of course, any other suitable tool can be used.

In addition to the Spudger, there are also bellows and lens brush.

The fastening system is simple:

The clamp at the back (red arrow) holds the focusing screen, the tab at the front with opening (green arrow) fixes it.

To release the focusing screen, I push the tab upwards with the Spudger.

The nipple on the screen then slides out of the opening of the tab and the screen is free.

The camera stands upright so that gravity pulls the focusing screen out of its position.

It would be ideal if I placed the tip of the Spudger in the middle of the tab to prevent bending the edges. But then I don't have a holding point for the Spudger on the screen and I can't press it down.

It would be possible to work with two hands and fix the camera, you have to try out what suits you. In my repeated attempts I didn't bend the tab or it already was.

The focusing screen can now be moved further down and pulled out of the mirror box.

Be careful, the screen can easily jam when pulled out in the mirror box. Since this only affects the edges of the screen, it cannot get scratched.

I wear gloves here and work with my fingers because I don't want to use tweezers due to the sensitivity of the screens surface.

Done

Now the underside of the prism and the focusing screen can be blown off with the bellows. The brush also helps.

To install the screen, I place the camera on the top cover.

The side with the elevations of the microprism ring and cross-sectional image indicator faces the underside of the prism.

Again, no tweezers

I carefully push the screen into the mirror box up to its holder.

Minolta X-700: A renovation project

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