Prontor-SVS stuck

[NorpA]

Hi there, I am really enjoining a small Mine-Six IIF in these days.
This camera is a little RF-folder produced around '50s. My version has a PRONTOR-SVS shutter associated with a DEEP-C lens. The camera is in good condition, with a nice finder and a smooth focus control, however I encounter quite often an issue with the release shutter mechanism. It simply stuck when released and I have to manually push it to restore the correct movement.

Is it common with Prontor-SVS?

 

[citizen99]

It seems that your Mine-Six IIF, which normally has a Japanese shutter, has been modified to take the Prontor-SVS, which I would expect to be the Size 00 version.

So,
1] I wonder whether the coupling to the shutter release has been correctly engineered.

Otherwise,
2] Does it happen with the 'fast' speeds (1/300, 1/100 ... ), or the 'slow' speeds (1. 1/2, 1/5 ...), or both?

If it only happens with the slow speeds, it may be only that the escapement needs cleaning.
Otherwise, if it affects the 'fast' speeds, there might be an additional problem.

 

[Solinar]

Prontor shutters do get sluggish. I usually remove the front and rear lens elements from the shutter. Remove the shutter from the camera. Then run the shutter at its slow speeds while immersed in bath of Rosinol for about 3 actuations. At which point I take it out of the cleaning liquid and let the shutter dry for a day. Retest the shutter before re-assembly.

Rosinol a.k.a. lighter fluid for Zippo cigarette lighters is naphtha and highly flammable. Naphtha is also used cooking fuel in old-school camp stoves.

 

[NorpA]

Does it happen with the 'fast' speeds (1/300, 1/100 ... ), or the 'slow' speeds (1. 1/2, 1/5 ...), or both?

If it only happens with the slow speeds, it may be only that the escapement needs cleaning.
Otherwise, if it affects the 'fast' speeds, there might be an additional problem.

Dear C,
it doesn't seem correlate to the escapement mechanism, since it also appears when shooting at 1/300.

Dear S.,
definitely an appropriate clean and lube procedure has to be consider soon.

Maybe in the near future I will post some pics to document this nice camera and evaluate with you its history.

 

[02Pilot]

Sluggishness across all speeds is often associated with contamination on the shutter blades themselves. The best solution I've found for this is careful cleaning with Ronsonol followed by gentle and sparing application of powdered graphite to the blades.

 

[NorpA]

tadaaa, I think we have a winner, dear P. your suggestion meets my observations. I truly believe the root cause has to be found in the lost lubrication among the shutter blades.

If I keep shooting (even with different speeds) I don' face the issue, whereas if I leave the camera unused for a while, it is highly likely to appear.

 

[NorpA]

This short video demonstrates how the issue occurs:

https://www.dropbox.com/s/h4aehfhbs90segv/Mine_Six_Prontor_SVS_b.avi?dl=0

 

[NorpA]

Solved unscrewing the front lens and gently cleaning the grease. The shutter works like a charm now.