J3 assembly

[Teus]

serviced an Industar a few days ago, went smoothly. Now it was the turn of my J3, but I can't figure out how to re-assemble the helical: I can't turn the focus ring when I put the helical back in and screw in the guide pins. When I turn hard enough, I just screw out the helical again. The rangefinder coupling doesn't move at all.

What am I doing wrong?

 

[payasam]

Patience, Teus. Brian Sweeney or Kim Coxon will be along presently.

 

[Sonnar Brian]

I've been VERY busy at work, and at home so this one got past me!

Okay- re-assemble the Helical. There is a mechanism that controls the throw of the focus near the top of the mount. As you look at the mount, upright, make sure it is all the way to the left before you start putting the helical back together. Then, there are several possible starting locations. You need to hit the right start so that the guide pin lines up at infinity. SO- focus throw slider set at infinity, helical started at correct location. I just dealt with a Canon 85/2 that seems to have 16 possible starting points. And it was sent to me "needing help".

Kim's site:

http://pentax-manuals.com/repairs.htm