[Stickle]

Hi I am not sure this is the right place to be posting this as this is my first post, so any help is appreciated!

I have recently purchased a Lexon chronograph with a valjoux 7730 movement. The base time keeping part of the watch seems to be functioning correctly, however whenever I run the chronograph, the second hand stops at 55 seconds and does not continue. The second hand does reset if the chronograph is stopped and reset. I am wondering if anyone has encountered this before and how one would go about repairing the watch.

I have noticed it appears to be missing a screw in one of the plates. I am not a watch maker but do have experience with mods and some basic service.

Thanks!

 

[Stickle]

I have just noticed as well that the chronograph will continue to operate if I apply pressure to the start/stop pusher from 50s to 5s. Also the watch is fully wound.

 

[Archer]

The watch is stopping when the extra load from flipping the minute counter is starting. This can be for a few reasons, but they are generally too much load, or not enough torque.

For too much load, for example the jumper for the minute counter is set to have way too much tension, that may be stalling out the movement.

For not enough torque, if the watch has poor balance amplitude when fully wound and the chronograph is not running, it won't have enough power to flip the minute counter even if the jumper is set properly.

So without more data on the service history of the watch, what the balance amplitudes are like, what the condition of the lubrication is like, it's difficult to give specific advice. Given that a screw is missing and may be floating around inside the movement, and the performance issues you are describing, I would say step 1 is a full service.

If you have not serviced a chronograph before, this probably isn't the watch to learn on.

Cheers, Al

 

[Stickle]

Thank you for the reply Al. That makes sense. I have found the screw and removed it from the case, and will look into getting it serviced.

Out of curiosity what would be a good chronograph movement to learn on? I have practiced on a unitas 6497 and a few vostok calibers so far.

Cheers,

 

[DonLuis]

Dry common with 7730/3

Besides of that is mentioned, 7730 has a pinion used to pass the minute recorder and a time setting gear, force when wha ting time in a movement what is nor property oiled can move it out of angle and cause fricción in the minute recorder.