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Discussion Starter #1
Bit of a theoretical question here but would the accuracy of a given automatic/mechanical chonograph be determined by the accuracy of the movement itself? i.e. if a Valjoux 7750 is keeping time to +2s/d then the chonograph would also be accurate to the same error as its being driven by the same balance wheel, escapement, mainspring etc. I say this assuming there is nothing slowing or speeding the system up between the shared timekeeping heart of the movement and the gears driving the chronograph.

I would love the input of someone who knows their mechanical watch anatomy.

Is this answer different perhaps based on the movement itself i.e. perhaps yes for a Valjoux 7750 or Lemania 5100 but no for the Dubois Depraz modules?
 

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Ordinarily, the rate of a chronograph is dependent on the rate of the balance. So, you will see a timing error in the stop watch similar to the error in hour/minute hands.

This is true of all chronographs whether integrated or modular.

That said, if the chronograph is not properly adjusted, you will see a rate change, as drag on the base movement can affect balance amplitude, and thus rate. (Also true of both integrated and modular, but generally, modular chronographs, such as the 2894-2, are more sensitive to poor adjustments in the module.)
 
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Discussion Starter #3
Ordinarily, the rate of a chronograph is dependent on the rate of the balance. So, you will see a timing error in the stop watch similar to the error in hour/minute hands.

This is true of all chronographs whether integrated or modular.

That said, if the chronograph is not properly adjusted, you will see a rate change, as drag on the base movement can affect balance amplitude, and thus rate. (Also true of both integrated and modular, but generally, modular chronographs, such as the 2894-2, are more sensitive to poor adjustments in the module.)
Thanks, thats very informative.

Based on that then, a well adjusted chrono should keep time at the same rate of the base movement while a poorly adjusted chrono can affect timekeeping of the min/hour hands as well as the chrono hands, in other words both top down and bottom up.

i.e. a watch keeping good time might slow down/speed up with chrono engaged (assuming poor adjustment?)

Is that correct? Might I extrapolate further and assume that changes in timekeeping with chrono engaged vs. off suggests that service is due?
 

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Yes, the rate of the stop watch portion are alway the same as the rate of the time portion.

Does it indicate a service is due? Not really, some places don't do a very good job adjusting chronographs at the factory or they get out of adjustment during casing. And, once adjusted, they really should not drift, they are mostly positioning stop locations.
 

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Discussion Starter #5
Excellent. Thanks for sharing your knowledge!
 
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