Minolta X-700: A renovation project

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koraks

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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

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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

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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.
 
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Andreas Thaler

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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.
 
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Andreas Thaler

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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.

 
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Andreas Thaler

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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.
 
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Andreas Thaler

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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.
 
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Andreas Thaler

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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

1.jpg


2.jpg


The areas repaired with Sugru have hardened after 24 hours.


3.jpg


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I use fine-grained sandpaper to smooth the areas.


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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.


6.jpg


Sanding


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Paint over with black gloss paint and let dry.


Check the clutch for the aperture simulation

8.jpg


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

9.jpg


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


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There is still rust on both screws.


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


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The screws get a bath in Durgol.


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


15.jpg


The parts waiting to be assembled.
 
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Andreas Thaler

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16.jpg


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18.jpg


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.


19.jpg


Same procedure for other screws with rust.


Assembly

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


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Now with the buttons and fixed with its two screws.


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

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


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The right part of the cover is assembled.


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Likewise the one on the left.


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


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The rust-free screws are now ready for installation.


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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.


29.jpg


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

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30.jpg


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.


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


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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 🙃


35.jpg


The top cover can now be put on.


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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.


37.jpg


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


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The ASA/Exposure Compensation Wheel is mounted.


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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.


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Rewind crank and back door are installed.


Functional test

44.jpg


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 🙂
 
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Andreas Thaler

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45.jpg


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


46.jpg


The exposure metering is also OK.

The measured values agree with my Nikon F3/T 🙂👍


On the catwalk

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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.
 
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KerrKid

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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. 😝
 
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Andreas Thaler

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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.
 
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Andreas Thaler

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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 🙂
 
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Andreas Thaler

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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 👍
 
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miha

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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

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

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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.

 
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Andreas Thaler

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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

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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?
 
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Andreas Thaler

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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.


1.jpg


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.


2.jpg


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


3.jpg


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.


4.jpg


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.


5.jpg


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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.


7.jpg


Done


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


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


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


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Again, no tweezers


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


14.jpg
 
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