Chronograph not keeping good time

[Omar]

Hi All,

I have a seiko 6139-7100 chrono, the watch was serviced twice in the past three months by two different watchmakers and both can't seem to figure out the problem, the watch itself keeps excellent time, but the chronograph is 2-3 seconds fast a MINUTE, which is crazy, any ideas on what is the cause? how can the time telling function of the watch be keeping accurate time while the chrono is not?aren't they both supposed to be depending on the same 4th wheel?

Thanks.

[JohnR725]

was chronograph running fine before serviced? Then if you run the chronograph over several minutes does the error accumulate? In other words in one minute it's 2 to 3 seconds fast 10 minutes it's running 20 to 30 seconds fast?

[Melt]

From TheWatchbloke web site........A big potential problem with the 6139 (and 6138) is if the centre wheel vertical clutch is worn. This is the component that engages and disengages the power from the drive train to the chronograph hands and can be seen in the centre of the movement. Once these are worn there’s very little that can be done in the way of a permanent fix to bring them back to life. It means the hand slips when the chrono is running and it also will start resetting to random positions. The proper fix is to fit a replacement, if you can source one!

Edited September 10, 2018 by Melt

[rogart63]

Think it could be as Melt say. It's probably the chronograph wheel. It's nothing you can do except to replace or live with it. Either run the chronograph all the time and adjust the watch so it runs good. That is the best for the wheel as it doesn't slip in the clutch. Or let it be as is and when i break find a new wheel. They are superhard to find . 

[Omar]

Thank you everyone, I think I'll just live with it as it is hardly worn anymore  and i hardly ever use the chronograph anyways. the error does in fact accumulate as the 30 minutes counter actually counts around 28 minutes yet the hands resets perfectly every time.