Technical question re automatic chronograph movements

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UncleDicky
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Technical question re automatic chronograph movements

Post by UncleDicky »

I've recently (last week) purchased my first Automatic Chronograph, a 2016 flavour Hamilton Broadway AutoChronograph bought from a forum member for a very reasonable price indeed.

I've not had much of a chance to wear it, but put it on today. This evening I was cooking the kid's dinner and decided to use the chronograph to time it. It works ok except the second hand is very slightly jerky between the 5-10m and the 10m-30m. You have to watch very closely to see this - it's irregular and not the smooth action you would normally see.

I suspect that the chronograph function is suffering from lack of use and given the watch is nearly 3 years old, I will send it in for a service.

Question -
automatics should obviously be worn every now and then to ensure that they don't start to play up, seize etc. With clockwork chronographs, is it a good idea to run the chronograph every now and then, also, if placed in a watch winder, should the chronograph be activated?

thanks

Rich
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Amor Vincit Omnia
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Re: Technical question re automatic chronograph movements

Post by Amor Vincit Omnia »

It’s a good idea to run any chronograph once in a while, but not to keep it running all the time. I would not use the chronograph while the watch is on a winder.
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Re: Technical question re automatic chronograph movements

Post by TG3N »

That’s a Valjoux/ETA 7750 movement, and regardless of age/useage, they’re known to be jerky/stuttery in the fashion you have described. Quite normal, if irritating. Check it out on YouTube. But the time-keeping should remain accurate regardless of how displayed. In general, I’m not a fan of keeping chronographs working more than they have to - unless vertically-clutched, you’ll often find that the tooth profile of the Chrono wheels is sharper, of the sort designed not to catch/clash/bind on activation, rather than the smoother type found in the normal gear profile, which are designed for consistent & constant power transfer. Perfectly normal.
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Re: Technical question re automatic chronograph movements

Post by UncleDicky »

TG3N wrote: Mon Oct 15, 2018 7:34 pm That’s a Valjoux/ETA 7750 movement, and regardless of age/useage, they’re known to be jerky/stuttery in the fashion you have described. Quite normal, if irritating. Check it out on YouTube. But the time-keeping should remain accurate regardless of how displayed. In general, I’m not a fan of keeping chronographs working more than they have to - unless vertically-clutched, you’ll often find that the tooth profile of the Chrono wheels is sharper, of the sort designed not to catch/clash/bind on activation, rather than the smoother type found in the normal gear profile, which are designed for consistent & constant power transfer. Perfectly normal.

Thanks, that's very reassuring.
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Re: Technical question re automatic chronograph movements

Post by Bahnstormer_vRS »

Yup, definitely reassuring as, whilst I've not noticed it, I have several Valjoux 7750 powered Chronos and will probably now be checking them.

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