Arri 16S self regulating motor disassembly

[Marc Roessler]

Does anyone know how to disassemble the self regulating motor of the Arri 16S? I have the version without the external transistor.

I would need to tweak the motor it a bit, camera only has ever been doing 22 fps with that one. (Camera works with other motors, so it's not the rubber coupler causing this)

For motor disassembly, the knurled turn knob in the back must first be removed. In other pictures I found online, knob can be removed after removing a screw holding it in place. Mine does not have any screw or anything like that there. Is the axis threaded and the knob just screwed on tightly? Press fit, i.e. needs to be pulled off? Or does the whole axis need to be pulled out towards the back, after removing the roundish metallic coupler in the front?

Thanks, Marc

[Fabian Schreyer]

Forum member @Duncan Brown made a very detailed documentation of the disassemby here: 

It seems to be offline right now, but I would just try again later or maybe DM him.

[Duncan Brown]

I’m on the road still for thanksgiving and there was a ton of snow in Chicago while we were away so maybe something went wrong (it’s a server in my basement). I’ll check it out this evening when I get home. 

[Marc Roessler]

Thanks, Duncan!

I had found some google cached images from that page during my investigation, but none of them showed the disassembly of the knob. Would love to take a closer look at the original page once it's up again.

[Duncan Brown]

The page still works for me, does it not for you?

http://backglass.org/duncan/arri/constant_speed_motor_24fps_teardown/

My motor, with the eternal transistor, has the screw that holds the knob on, so that part may not be much help to you anyway.

Duncan

[Duncan Brown]

Ah - I see the OP is from Germany, and I've had weird problems before with people anywhere in Germany reaching my server.

Try this:

https://betlikeduncan.pairsite.com/16mm/constant_speed_motor_24fps_teardown/

Duncan

[Mark Dunn]

On 12/2/2025 at 1:18 AM, Duncan Brown said:

The page still works for me, does it not for you?

http://backglass.org/duncan/arri/constant_speed_motor_24fps_teardown/

My motor, with the eternal transistor, has the screw that holds the knob on, so that part may not be much help to you anyway.

Duncan

Not working here either.

Non-compliant with GDPR? Some US ISPs don't bother, just block.

Edited December 3 by Mark Dunn

[Duncan Brown]

That must be it!  Who knew.  I am in the process of moving all the sites from the existing server (OpenVMS!) to a Unix server and that would make it easier to get the proper certificates, I'll look into that.

Duncan