Zorki 4 sticking RF cam

[OMboy]

While sorting out my recent FSU purchases, I have discovered that the rangefinder cam in my Z4 is sticking and consequently the rangefinder is not working correctly.

I have followed a servicing PDF found on the web and removed the top cover and I think the moving parts just need cleaning and lubing (if necessary).

Problem is - I can't undo the screw holding the cam lever from inside the lens mounting hole. The angle needed to get a small screwdriver in through the lens mount is restricting the amount of pressure I can apply to the screw head.
I have even removed the lens mount and shim but it made little difference.

As I understand it, after removing the cam link from inside, the linkage on top (between the viewfinder prisms and the RF prism) can be gently pushed aside and the actuator rod should push up through the upper plate to make cleaning a simple process.

Am I missing something? Is it possible that the cam return spring has just weakened...?

I also noticed a point of movement at the RF prism but I'm reluctant to dribble Ronsonol into this pivot point as I don't want to damage the RF prism.

I have searched for an hour or two in vain before resorting to asking another question here but didn't find any useful info relating to 'sticking RF cam' or 'Zorki 4 stuck rangefinder' and so on.

Any suggestions would be very welcome.

 

[batterytypehah!]

You may have figured this out on your own by now -- I think you need to pull the body shell and remove the cover plate and light baffles. (See Rick Oleson's pages and stickies in this forum.) Even so it's not a straight shot for that screw, but might be enough. Pulling the body is not a big deal, but do take notes where each screw goes, they're not all identical.

I haven't had to do this myself yet, so I'm not sure if you'll be able to get the screw like this. Might still need a small angled driver so as not to mess up the slot. I have my own Z-4 in pieces on my desk right now but the RF arm is not the problem.

 

[wolves3012]

It would be much easier to remove the whole RF mechanism by taking it out from above. Pop the top cover off - there's a sticky on the Z-4/4K at the top of this sub-forum. The RF mechanism is held on by about 4 screws (IIRC). That way, you can get at the whole thing quite easily. One thing to beware of: DO NOT touch the mirror behind the RF window. It's surface-silvered and you WILL damage it if you touch it or try to clean it. While you're in there, check that the return-spring is not simply displaced. The RF pivots don't normally seize up. A tiny drop of thin oil should fix it though. And the screw-head you are referring to is VERY tight. It would be best to avoid trying to remove it, you probably won't need to if you try this approach.

EDIT: I can't recall if all models used the mirror, yours may have a prism instead. The 4K certainly has a mirror.

 

[OMboy]

Thanks for the suggestions - I will try and remove the RF as a complete unit first and see how that goes.

 

[wolves3012]

Thanks for the suggestions - I will try and remove the RF as a complete unit first and see how that goes.

One more suggestion then - under the RF is one of the shutter tension roller pivots - oil it while the RF is off!

 

[OMboy]

Well I've had some success.

I managed to drip a tiny drop of Ronsonol onto the pivot point for the RF cam and worked it for a few minutes then left it overnight.
Next morning I worked it some more and it seemed much better so I dripped a tiny drop of 3-in-1 oil onto the cam pivot and the bearing pivot at the RF end of the mechanism and...no more sticking...!

I've just been having fun putting the top back together (don't you just love micro grub screws 😱) and the RF is now working beautifully.

I'm going to shoot a roll of Reala through it and examine the results.

Thanks again for the help.

 

[wolves3012]

I've just been having fun putting the top back together (don't you just love micro grub screws 😱) and the RF is now working beautifully.

For future reference, most of the grub-screws are better just loosened and not removed - for reasons you've discovered! I tend to loosen them enough to remove the component, then do them back up a turn or two once it's off, to make sure they don't fall out.

Glad the RF is sorted and working anyway - enjoy!

 

[batterytypehah!]

Excellent! Unfortunately, I don't think I'll ever be able to get the top off my own Z-4. Somebody messed up the advance knob grub screw before the camera got to me. Drilling it out would mean finding a replacement screw and (likely) advance knob.

Ah well, I only paid $25 shipped incl. an I-50, and for the moment at least, there is no real reason to pop the top. The RF works correctly and gives a good picture. So, for the moment, I'll live with it.

 

[OMboy]

Those grub screws are micro - I don't think the one in my Z4 had ever been out but it still took a lot of care.
If the grub screw in yours has been removed before it's very likely the head has been chewed up.

Thanks for the advice on just loosening rather than removing them in future Wolves...!

 

[wolves3012]

Those grub screws are micro

If you think that's micro, take a look at the ones on lenses! If you have the J-8 on that Zorki 4, look around the lens to see micro.

 

[wolves3012]

Excellent! Unfortunately, I don't think I'll ever be able to get the top off my own Z-4. Somebody messed up the advance knob grub screw before the camera got to me. Drilling it out would mean finding a replacement screw and (likely) advance knob.

Ah well, I only paid $25 shipped incl. an I-50, and for the moment at least, there is no real reason to pop the top. The RF works correctly and gives a good picture. So, for the moment, I'll live with it.

The grub screw only prevents the knob unscrewing, if you drilled it out carefully it would only mean the knob could be unscrewed when turned the "wrong" way, which wouldn't be an issue. I agree though, if it ain't broke - don't fix it!

 

[OMboy]

If you think that's micro, take a look at the ones on lenses! If you have the J-8 on that Zorki 4, look around the lens to see micro.

I do have a J8 on my Zorki - it's a good job I have excellent eyesight...!

I have three different miniature flat-bladed screwdrivers - 2.4mm, 1.8mm and 1.4mm - should I be considering some smaller ones...? 😱