Zorki 4 - fast speeds are all the same

[domdel]

Hello,

I have just performed a CLA on my third Zorki 4 (based on the great sticky), and just came across a problem I've not encountered before: slow speed mechanism works like a charm, however all fast speeds (incl. 30th) act the same, i.e. the second curtain travels with the first one without any delay. Fiddling around a bit it seems like there is looseness in the rewind knob when cocking the shutter (it moves back slightly) and this seems to be the cause. If I retain the knob with the thumb once armed and then fire the shutter, my speeds work correctly (gradually increasing from 60 to 1000).

Apologies if I'm not able to describe it as accurately as I would like, english is not my mother tongue 😀

Looking forward to your expert feedbacks! 🙂

Greetings from Switzerland,
Dominique

 

[xayraa33]

Hello,

I have just performed a CLA on my third Zorki 4 (based on the great sticky), and just came across a problem I've not encountered before: slow speed mechanism works like a charm, however all fast speeds (incl. 30th) act the same, i.e. the second curtain travels with the first one without any delay. Fiddling around a bit it seems like there is looseness in the rewind knob when cocking the shutter (it moves back slightly) and this seems to be the cause. If I retain the knob with the thumb once armed and then fire the shutter, my speeds work correctly (gradually increasing from 60 to 1000).

Apologies if I'm not able to describe it as accurately as I would like, english is not my mother tongue 😀

Looking forward to your expert feedbacks! 🙂

Greetings from Switzerland,
Dominique

Clarify what you mean by "rewind knob", do you mean the knob at the end of the camera that you turn to get the exposed film back to the cassette, OR do you mean the A-R knob that is coaxial to the shutter release to disconnect from the gearing to make film rewind possible ?

 

[domdel]

Clarify what you mean by "rewind knob", do you mean the knob at the end of the camera that you turn to get the exposed film back to the cassette, OR do you mean the A-R knob that is coaxial to the shutter release to disconnect from the gearing to make film rewind possible ?

Apologies, I mean the film advance knob, on the right side of the camera (when holding it to take pictures), with the frame counter.

 

[xayraa33]

I would make sure that the shutter curtain tension on both curtains is correct , then check to see if the second curtain catches or latches are doing their job and the release pawl is in the correct position.

If you removed the slow speed escapement mechanism and re-installed it make sure it was installed correctly and not askew.

Wolves 3012 is the RFF forum member with the expertise on the Zorki 4 camera, give him a PM or wait for him to chime in, as he has helped many on Zorki 4 problems.

 

[wolves3012]

It's been a while since I worked on a Zorki 4 but I seem to recall the earlier versions have a non-return mechanism using a spring coil around the wind shaft and later ones have a ratchet and pawl (instead or as well, I can't recall). You might want to check that whichever parts are fitted are working properly. You'll need to remove the winder-knob and the take-up spool to access these parts but the pawl (if fitted) should be easy to see above the take-up spool.

If the winding mechanism slips back, it's possible the second curtain latch may fail to work properly. The latch is the curved arm by the speed selector and it should have a spring that pushes it downwards and inwards towards the selector. It would be worth checking that the spring is present and correctly seated while you're in there, since the slow-speeds don't rely on it.

Report back on what you find and if you're still stuck I'll try and point you in the right direction.

 

[domdel]

Hello both, thanks for the feedback already!

@wolves I have checked and indeed have the non-return mechanism using a spring coil around the wind shaft. It seems to work properly however I'm guessing the slipping back is the cause of my issue, the latch is failing to catch the second curtain in B mode for example.

The rest is fitted properly, including the slow speeds mechanism.

 

[wolves3012]

The first picture doesn't show the non-return spring, it's inside the spool spindle. I'm not sure if you thought the spring in the photo was the non-return spring or not?

Inside the spool spindle you'll find a shaft with a spring coiled tightly around it, the top end is anchored by the small, roughly curved-oblong block you can see next to the gears. I'd say that spring is not coiled tightly enough if the wind-on mechanics can slip back - that's likely to be the root of the problem.

I had a similar problem with an older Zorki 4 but not bad enough to give the problems you're having. On mine, it allowed just enough slip-back to upset the slow speeds. I cured it by fitting the secondary latch/shutter brake taken from a scrap Zorki 4K but that probably isn't helpful to you!

 

[davidnewtonguitars]

The non-return spring has a full S-bend-and-loop on the end, so make sure the spring is fully around both screws of the hold-down piece.

 

[domdel]

Inside the spool spindle you'll find a shaft with a spring coiled tightly around it, the top end is anchored by the small, roughly curved-oblong block you can see next to the gears. I'd say that spring is not coiled tightly enough if the wind-on mechanics can slip back - that's likely to be the root of the problem.

That sounds indeed like the most likely reason. I'll check this and revert.

 

[domdel]

Mmmm no luck so far. I've cleaned the winding mechanism (lighter fuel) and refitted the spring coil, seemed to work for a while (cocked and fired the shutter 20-30 times successfully with proper speeds for B, 1/30 and 1/60) and then it stopped working again, back to stage one :bang:

I've posted a small video on YouTube: https://www.youtube.com/watch?v=4gcXw60CLFM

This small backward movement is what is causing the issue. Could it be the gears (the ones that link the winding mechanism to the film sprocket)? I've put some grease there, maybe too much?

 

[wolves3012]

Looking at the video, the non-return spring is failing to do its job it seems. I don't think greasing the gears has anything to do with it but you should only grease them sparingly anyway. There could be some play at some point, such as the spring's attachment or a loose-fitting part somewhere - worth a check over. Failing anything obvious, I'd re-strip the spool drive and make sure it's all clean, dry and smooth (no grease/oil on the spring) and possibly then try coiling the spring tighter - not easy, I know - try and tighten the spiral so it's harder to re-fit over the shaft.

Other than that, you're a bit stuck unless you can obtain a replacement part (unlikely) or you can can acquire the latch from a 4K, like I did.

 

[domdel]

Thank you wolves, I'll clean again and try to tighten the spring. Fingers crossed!

 

[domdel]

So...:

• Tried to tighten the spring - didn't change anything...
• Tried to tighten the screws that hold the gears linking the spool spindle to the film sprocket (the one in the middle was a bit loose) - didn't change anything...
• I had put a bit of grease in the black shaft for the spool spindle (to make film advancing smoother), removed/cleaned it as I (correctly) suspected this was the culprit - didn't change anything...

Eventually I solved it with an ugly fix: I've put a very small bit of scotch tape on the spindle shaft and refitted it, it is now working perflectly as it acts as a brake and holds the spindle in place when the shutter is cocked (and it doesn't make it harder to turn the knob really) 😀
Maybe not the most elegant fix but it works for me.

Thank you all for your advice and help, much appreciated!

 

[Sumarongi]

Eventually I solved it with an ugly fix: I've put a very small bit of scotch tape on the spindle shaft and refitted it, it is now working perflectly as it acts as a brake and holds the spindle in place when the shutter is cocked (and it doesn't make it harder to turn the knob really) 😀
Maybe not the most elegant fix but it works for me.

Thank you all for your advice and help, much appreciated!

Dear Dominique ,
it's a Russian camera, you made a very Russian DIY-repair — that's perfect! 🙂

 

[domdel]

Indeed! 😀