Zorki 4K 1/30th sec question

[mordant]

First of all, huge thanks to everyone whose knowledge allowed me to CLA my 4K. However, I'm left with a perplexing problem - the 30th sec speed doesn't work properly as the brake cam gets trapped by the brake latch immediately after releasing the shutter (ie. acting like 'B'). All other speeds are fine. I have checked shutter curtain tension (5 turns and 3 turns as recommended). Can anyone offer any advice?

 

[ForestCap]

My Zorki-4 behaved exactly the same with yours when firing at 1/30. It acted like B.

I cleaned the dried grease in between some cogs and it works like new now. You need remove the front plate (where the lens mount sits on) to have the cogs exposed, at the lower part of the camera. By doing so you can also make the curtain drums exposed and do further examination. I'm not sure if you missed those cogs since you've done a CLA?

The tension on my Z-4 doesn't go as many as 5 turns. I think it's around 3.5 turns and 3 turns on mine. According to wolves3012's posts 5 turns would be too many.

There are some sticky posts in this sub-forum and they will be helpful.

 

[mordant]

Thanks for the reply. I did go that deep during the CLA - in fact there wasn't any obvious dried grease around those cogs. It does seem as though 1/30th is the most sensitive to any friction in the mechanism and the build tolerances are not that great so, at least with mine, I have to check the shutter at every stage of the rebuild to make sure a rotating part is not rubbing somewhere. However, the cam getting caught by the latch at 1/30th seems odd - and frustrating!

 

[wolves3012]

Tensions of 5 and 3 turns would be at the very top end of what I'd expect on a CLAd mechanism, which suggests something isn't as clean and free as you thought. Read the current "Zorki 4 back question" thread since I think you may have a related problem with the curtain latches. If the latches aren't working properly, it's usually highest speeds that work like B but it can be any of the "fast" ones or even all speeds.

 

[mordant]

Thanks for the reply Wolves3012. I'm putting a test film through at the moment but will review the tensions after (I think the 5 & 3 came from one of the 'other' CLA guides). This camera may have been messed with before as I found a 'long' screw in the left-side baffle that intermittently prevented the curtain roller from turning smoothly. Frustrating little beasts, aren't they!