Valjoux 7750 chrono reset

[Ageorge1988]

I've just finished stripping down, repairing and servicing a 7750 (Chopard)

I was testing the chronograph function and noticed that each time I start, stop and reset it, the Chrono seconds hand is resetting to a later position.

So the first time it reset to zero, the second time it reset to 1 second past, second time it reset to 2 seconds past and so on. 

Really can't work this one out, my guess is the cam isn't resetting the hammer correctly or something in that location.

Any help would be really appreciated.

[JohnR725]

Another thing that can cause the problem is? Did you notice how fast the second hand moves when it resets like really fast. The chronograph hands usually have go on with a lot of force otherwise when resetting they may go past where there supposed to be. It's why a lot of the watch companies they don't quite hammer the hands on but they go on with a heck of a lot of force and usually trying to remove them you destroy the hands. It's a common problem with some chronographs. It also means they hands have to go on with the proper force and ideally the proper movement holder to support things on the backside so they don't pop out when to putting the hands on.

 

[CWRNH]

13 hours ago, Ageorge1988 said:

I've just finished stripping down, repairing and servicing a 7750 (Chopard)

I was testing the chronograph function and noticed that each time I start, stop and reset it, the Chrono seconds hand is resetting to a later position.

So the first time it reset to zero, the second time it reset to 1 second past, second time it reset to 2 seconds past and so on. 

Really can't work this one out, my guess is the cam isn't resetting the hammer correctly or something in that location.

Any help would be really appreciated.

The hand is loose on it's arbor.  You will have to stake it to tighten it.