Valjoux Chrono issue...

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artphotodude
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Valjoux Chrono issue...

Post by artphotodude »

So I've had an issue with a 1970's Valjoux chronograph (7734) for some time that I've been told relates to a cam adjustment. The minute register will often get thrown a minute or 2 when starting the chrownograph function. After 3 trips to the shop, the last one seems to have fixed the issue, but now sometimes if its been some time since winding, or when the calendar is advancing, the watch will stop when the chrono is running. So it seems the can is slightly too tight.
Considering, how hard the problem seems to be to correct, and considering how good the time-keeping averages, my current intention is to use it more to hopefully break-in the movement to this new adjustment, and see if it can aclimate to the new working setting. Are there any things wrong with this idea, or other measures to take?
Thanks!
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watchaholic
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Re: Valjoux Chrono issue...

Post by watchaholic »

The running chrono as well as the date change all take power from the mainspring. If the watch is stopping, sounds like a good wind would keep things working proper. Running the chrono shouldn't hurt anything, but I'm not sure its necessary.
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Re: Valjoux Chrono issue...

Post by Bahnstormer_vRS »

^^^^ Following on, what is the Power Reserve like on a full wind? Is it up to spec?

Other than that, to use it and let the current / new adjustment and any parts bed in, seems like an excellent idea.

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artphotodude
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Re: Valjoux Chrono issue...

Post by artphotodude »

watchaholic wrote: Thu Jun 17, 2021 12:48 pm The running chrono as well as the date change all take power from the mainspring. If the watch is stopping, sounds like a good wind would keep things working proper. Running the chrono shouldn't hurt anything, but I'm not sure its necessary.
That's exactly what I've done! When just using as a watch, it does great (+-4-7 sec/day), but whenever I use the chrono very extensively (like when exposing prints for photography), I will top-up the wind to hep it push through. This works great when I'm working my night job and time my lunch as the calendar is turning over. One watch repairman in LA wanted me to mail it in "Right Away" to avoid doing damage to it, but my experience is that watches are a lot tougher than we give them credit for and since the chrono after this last adjustment is finally working right, it makes sense to see if a new normal can be reached. It's an old watch, not even made of an exotic metal (a good user) and am hoping to lean on it a bit and see if it can reacquired equilibrium. Obviously, this probably does wear certain parts a bit of faster rate, so will probably open the back and blow it out (gently) in case some extra metal dust is being created during this process.
Bahnstormer_vRS wrote: Thu Jun 17, 2021 2:14 pm ^^^^ Following on, what is the Power Reserve like on a full wind? Is it up to spec?


Other than that, to use it and let the current / new adjustment and any parts bed in, seems like an excellent idea.

Guy
Not sure what spec is, but I normally get about two days.
Thanks for the replies!
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Re: Valjoux Chrono issue...

Post by rkovars »

There is some debate on the actual power reserve but anywhere between 40 and 45 hours seems about right for a movement of that age. Obviously running the chrono will eat into this number. Age on the mainspring would also lower this number. But, to your observations it seems about right.

My hand wind chrono I top up every time I put it on when I wear it for consecutive days.
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