I started my chrono on my 861 to time my commute yesterday, forgot to stop it and then noticed that my watch had gone flat. To be sure I reset the time, wound it and started the chrono again. Six hours later, the watch stops. I wound it again but didn't start the chrono and it rand for the rest of the evening, all night and today. I was was still running this afternoon, nice as you like, so I wound it up and started the chrono. Again, six hours later and it's flat. It was only serviced recently so I'll have to send it back but any ideas as to the cause?
running the chrono on a 861 should only knock off about an hour of the power reserve (typically 50 hours on a full wind). does it start again if you stop and reset the chrono?
i'm sure Al will explain this better than I can but it looks like whoever did the service got the tolerances on the chrono running gear a bit wrong.
Could be a lot of reasons...too much tension on the friction spring, too much engagement between the coupling yoke and chronograph runner, or between the coupling yoke and drive wheel... Did you look at the hands to make sure they were not binding? Sometimes a counter hand will bind when it is in a certain position on the dial and the main hour hand comes around to contact it. Resetting clears the interference and the watch runs again. Like I said, could be many things..... Cheers, Al
Thanks for the input guys. I'm away now for a couple of days but I'll check your suggestions when I get back.
I tried it again today and as before, the watch stopped after around seven hours. However, when I pressed the start/stop pusher it started again. This was before I pressed the reset pusher. Ive sent it back to my watchmaker to take a look at but I'd be very interested to know the cause.