Valjoux 7750 Running Issue

[mcoulton]

Hello 

I've never worked on a Valjoux 7750 (clone) movement and so I have some issues that have cropped up and am looking for some answers. 

1.) As I progressed through the assembly I noticed the balance wheel had stopped  moving just before I was about to put the hands on. So I started to disassemble the components and it wasn't until I disassembled the chronograph module (dial / automatic oscillating weight / calendar works / chronograph) that the balance wheel started up on it's own. My question is what could have prevented the balance from spinning? When the watch was assembled I tried to move the wheel using a probe, however it wouldn't spin up. It wasn't until I continued stripping the movement that the balance started oscillate on it's own. 

2.) When manually winding the movement I never get to the point where I couldn't wind it anymore. Is this a function of how the mainspring operates in an automatic movement or should I further strip the movement and check the mainspring to see its broken?

Thanks in advance for any help that can be provided. 

[tomh207]

1. I would suspect that when you add one of the chrono parts something binds. I don’t believe the 7750 is a module based chronograph, maybe terminology here?

2. In an automatic movement you can wind it forever as the spring is designed to have a controlled slip on the barrel wall with the appropriate braking grease.

 

Tom

[eccentric59]

If the movement won't run even with the chronograph disengaged, then the first place I'd look is make sure you have the oscillating pinion (shown below on the right) the right way around. It will fit either way, but I believe the one side is just a hair taller and if put in incorrectly will bind.

[mcoulton]

Thanks for the feed back. I will review Marks video regarding the oscillating pinion and see if I installed it upside down. Thank you for confirming the operation of the mainspring. Now I know I don't need to strip the movement completely down.