Minolta X-300 put back into service

An X-300 with some signs of wear and a dent on the side of the top cover, a bit dirty - a basement find, as the previous owner told me.

The shutter is cocked, the LEDs in the viewfinder remain dark when the trigger is tapped, pressing the trigger does not release the shutter.

Ok, let's see what can be done.

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Checking the power supply is always the first step I take when an electronic camera has issues with the LED display and shutter.

Therefore I begin with cleaning the battery chamber.

A little over 3 volts can be measured from the positive terminal of the battery to the battery chamber cover. This should mean that the contact to the negative pole is ok, as this value corresponds to the open circuit voltage of the battery.

New attempt, the LEDs now turn on (or had I overlooked it before?), but go out again after about 1 second.







I unscrew the base plate and look at the electrolytic capacitor and the circuit board installed there.

Apart from some dirt and a small spot of corrosion, nothing unusual can be seen.




I then unsolder the electrolytic capacitor and check it with the Peak atlas ESR 70 gold, a measuring device for electrolytic capacitors. (The picture shows measuring of another electrolytic capacitator).

The measured capacitance and ESR values are in target. Therefore the capacitor should be ok.

I solder in a new one because the old capacitor has already served for decades and could leak.




The operating voltage of 3 volts is present on the circuit board and also on the electrolytic capacitor.

That's good because it means the power supply works up to this point and the electrolytic capacitor is also charged.

But nothing changes, the camera still doesn't fire.

Looking at the rear shutter curtain, I notice a metal bar on the cloth peeking out from under the film window. Actually this bar shouldn't be visible.




I turn on the camera and carefully push the metal bar to the left using a case opener.

I hear a CLACK and - yes, the X-300 acts as if nothing ever happened.

Everything works again as it should

The fix for one of the more common shutter issues on Minolta X cameras has helped.

Now let's do a bit of cleaning and maybe I'll find a replacement for the missing thumb rest next to the shutter button


Cleaning (1/3)

Since the top housing cover in particular is dirty - and I would like to take a look under the hood anyway - it's time to disassemble.






The best way to clean the cover is in a bowl with water, dishwashing liquid and a toothbrush.

Otherwise I would have to clean all the nooks and crannies and that is not only tedious, but it also never gets as clean as when there is a full bath




Three cables need to be unsoldered.




The data center




The small plastic stop bar that forms the stop for the dial of the frame counter has broken off.

A common problem with the X cameras.

The dial then does not stop at the "S" position when the rear cover is opened.

But I have a replacement, at least I hope the disc from a Minolta X-700 will fit.






The dent on the side of the case cover did not continue inside.




Dirt has only stuck to the edges of the cover.

The circuit board itself is - like in all the X-Minoltas I've opened so far - clean.

Isopropyl alcohol dissolves but leaves streaks ...





... which can be removed with a little Aqua purificata.

Nice work!

Cleaning (2/3)








The attachment and components of the main switch on the inside of the top cover.






In order to be able to clean the rear side of the eyepiece, which closes with the prism, I remove it ...




... and reinstall it after cleaning is done.




To keep the removed parts until the next session I place them on a plate and put it away in a safe place.




There's a lot going on at the table - and a lot to clear away after work ...


What still needs to be done:

- replacing the defective dial in the frame counter
- cleaning
- replacement for the missing thumb rest next to the shutter button
- assembly



The frame counter




Fortunately, a working dial can be removed from an X-700 and taken over.

Above is the donor camera, which has already been heavily dismantled, and below is the X-300.




The dial can be removed after removing its holder.

To do this, it must first be lifted off a locking pin.




At the bottom left is the spring against which the disc rotates.

If you open the back of the camera after taking pictures, the dial snaps back to the "S" position.

That's what the small stop bar is for, which is now there again.




The replacment dial is inserted into the X-300.

Starting from the 36 on the disc, the disc must be turned counterclockwise once so that the spring takes up tension.

Then the holder can be put on.




Test passed.

The dial now goes to position "S" as soon as the back cover is opened.

Cleaning (3/3)









Dishwashing detergent, drying, blowing the moisture out of the joints with compressed air and a warm shower.

Now the parts are - almost - clean.

After assembly, I use cleaning sticks to clean up any dirt that still remains.



The thumb rest



At the front is another X-300 that still has the black thumb rest.

Behind it is the repair candidate.




Since I don't have a replacement, I have to build one.




Sugru - "the mouldable all-purpose glue" - is ideal for this.




The mass can be kneaded and shaped into any desired shape.

It hardens within 48 hours.






The holding plate is filled with Sugru.




The ribbing can be pressed in using the existing thumb rest as a stamp.

Done - now let it dry out,

Assembly






The main switch on the top cover connects to the switch on the circuit board via a pin.

A retaining ring fixes it from the inside.

Since the retaining ring no longer holds properly - probably because it was levered out previously - I melt the plastic pin a little with the hot air gun.

Now it sits firmly even without a retaining ring.






There is a transparent plastic film inside the top cover above the prism, which has come loose on one side.

Fixing with double-sided adhesive tape is quicker than with glue.




The three cables are soldered on again.




Returned to service

Film safe load signal does not work correctly


After installing the X-300, I saw that the film safe load signal, the orange bar behind a small window, shows a correctly transported film.

But no film is inserted.




Here is the position of the film safe load signal.




And with the top cover removed.


Knocking on the housing causes the orange bar to move.

The film indicator is obviously disengaged.

So I have to remove the top cover again.

To do this, I have to drill out the Sugru thumb rest over the two screw heads underneath in order to be able to remove the retaining plate. Only then can I remove the film transport lever.

Fine and precise drilling is therefore required in order to be able to loosen the screws.

Otherwise I would have to remove the thumb rest and redo the Sugru work.

So I just need to close the drill holes after the thumb rest is on again.

I'll take a look at it with the next Minolta X camera that comes in for a check.

Before that, I will consult the service manual to explore the mechanism of the film indicator.

Repair of the film save load signal (1/2)


The orange bar under the small viewing window to the right of the shutter button has a life of its own (see the thread above).

It should only be visible when the film is pulled through and should indicate its correct transport by moving steadily to the right without swinging out.

It swings back and forth in the X-300.

So let's get to work.




Since the thumb rest, which I recreated with Sugru, needs to be unscrewed before removing the top cover I use another X-300 to measure and mark the screw head positions underneath.




Now I can gently expose the screw heads using the Dremel Stylo and a suitable drill ...




... and can unscrew the thumb rest.

When everything is done, I close the holes again with Sugru.




An abandoned X-700 - in the picture below - whose film counter is still intact quickly shows the problem:

In the X-300, the film indicator lacks a spring that presses it against the axis of the film winding lever.

This makes it clear that the small bar has no support and cannot correctly display the transport of a film.




Here you can see how the spring is attached to the X-700.

The orange bar is placed on an axle and can be removed.




To do this, I first dismantle the dial of the image counter so that I don't have to lever out the bar and spring.




And two spare parts have already been collected




Assembly of the two parts in the X-300.

The arrow shows the attachment of the lower end of the spring to the housing.




When assembling, I thread the dial under the film indicator.

The arrow here points to the end of its associated spring, which hooks onto the housing.




Fixing the structure with the holding plate




Ready

The orange bar is now firmly seated and is held in position by its spring.

Repair of the film load safe signal (2/2), fixing the film advance lever and finish




After assembly I notice that the film advance lever runs against resistance.

The cause is the upper end of its spring which is too far up.




This causes the end of the spring to scratch against the underside of the thumb rest.

The effect can be seen here.




With this short length, trying to bend the end of the spring is futile.

Since the spring, inserted the other way around, also scratches, I reach for one of my heaviest weapons

The side cutter with an inserted carbide cutting edge from Knipex shortens the protruding part of the spring without any effort.




Now the scratching has stopped.

Since the thumb rest sits directly on the winding lever, I apply a thin layer of Ballistol silicone oil, which reduces friction.

I'm suspicious that the thumb rest and the film winding lever make contact.

Something in the ensemble may be bent here; a drop mark can be seen right next to it on the edge of the case.

I loosen the screws of the thumbs rest a little to add some clearance.








Now I can fill the holes again with Sugru.




The X-300 is fully restored.

The Minolta MC 50/1.7 to be seen on the picture will be its own repair project.

There is a dent in the filter thread and cleaning is also necessary.




Thanks to my two abandoned X-700s, who again willingly and selflessly made themselves available for study purposes and to donate spare parts!

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cerber0s said:

Nice work!

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Thanks

Great work! Always nice to see a camera coming back to life.

Flighter said:

Great work! Always nice to see a camera coming back to life.

Click to expand...

Thank you