# Regulating A Valjoux 7750 Movement



## Chromejob (Jul 28, 2006)

My new Chenevard chrono (Valjoux 7750 inside) seems to be losing 5-10 secs per day ... not a very auspicious beginning. I've been tinkering with my basic Seiko movements, but wondering if anyone here has suggestions for regulating this movement. Dare I open the case (oops ... need a new case opening tool), or should I use a pro for such tinkering? TIA....


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## Chromejob (Jul 28, 2006)

Oh ... I just remembered that some have mentioned *new watches need to "settle in" *(like audiophile headphones).

How long do you blokes generally allow a watch to "break in" before tweaking? Do you use any routine of wrist + case + winding during this period?

(Be gentle with me. It's my first new Swiss movement. All others have been pre-owned.)


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## JoT (Aug 12, 2003)

Dead easy  wrap some duct tape around your hand sticky side out and use this to take the back off then give the regulator a poke with a cocktail stick, job done! Here's a close up of the 7750 to give you some idea. As for breaking in I have never bought into that hypothesis, certainly not for a Swiss movement.


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## Chromejob (Jul 28, 2006)

JoT said:


> Dead easy  wrap some duct tape around your hand sticky side out and use this to take the back off then give the regulator a poke with a cocktail stick, job done! Here's a close up of the 7750 to give you some idea. As for breaking in I have never bought into that hypothesis, certainly not for a Swiss movement.


Not sure if the duct tape will work on a dive watch, but ... hrm, worth a try. But MUCHAS GRACIAS for the pic, tells me exactly what to expect.


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## Defender (Jan 27, 2009)

Hi there,

I think you'll need one of those 'squashie ball' type back removers and a case vice for that back?

My Fortis B42 Pilot Professional (7750) Chronograph runs very slightly fast, never bothered to regulate it though, can't comment on it needing breaking in as it was 'pre owned' when I got it.

Best regards,

Defender :astro:.


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## Chromejob (Jul 28, 2006)

JoT said:


> Dead easy  wrap some duct tape around your hand sticky side out and use this to take the back off then give the regulator a poke with a cocktail stick, job done! Here's a close up of the 7750 to give you some idea. As for breaking in I have never bought into that hypothesis, certainly not for a Swiss movement.


Great advice, but when I opened up my Chenevard, the "eccentric screw" and adjustment arm were not there, just a little hole where the adjustment arm might go. ... I moved the bar on the lower right a smidgen, presuming that the other bar (with the gold pinion/thing) is the isochronism regulating arm.

Oddly (more like disturbing), no "ETA" or "7750" marks are visible anywhere on the movement (seen from the removed caseback).


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## Chromejob (Jul 28, 2006)

David Spalding said:


> ... I moved *the bar on the lower* right a smidgen, presuming that the other bar (with the gold pinion/thing) is the isochronism regulating arm.


OOPS. Wrong. :blush:


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## clockworks (Apr 11, 2010)

hard to be sure from the pics, but I think that the one with the gold stud is the regulator (curb pins) while the one with the silver stud is the beat adjuster.

I guess you've just realised this?


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## Chromejob (Jul 28, 2006)

clockworks said:


> hard to be sure from the pics, but I think that the one with the gold stud is the regulator (curb pins) while the one with the silver stud is the beat adjuster.
> 
> I guess you've just realised this?


Yep, ah, is the "beat adjuster" the same as an "isochronism" (term I picked up from someone's DIY servicing guide using a Seiko 7S26 as an example). This puppy will probably need a few minutes on a watchsmith's Greiner(?) regulating device. Though I've now got it gaining x seconds a day, not losing (which I prefer).

Movement revealed.... Click the pic to see the 1280W version.


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## clockworks (Apr 11, 2010)

Sort of connected, but not really the same. If the watch is out of beat, isochronism will be poor - the rate will change more as the spring runs down.

If you look at the 2 "adjusters", one is at the end of the spring, holding it firmly. Moving this one will alter the resting position of the balance, since the balance is connected to the other end of the spring. This, in turn, will alter the resting position of the impulse jewel relative to the pallet fork. The idea is to set this stud so that the balance swings equally either side of the pallet fork. AFAIK, this should also give the maximum amplitude to the balance (biggest arc of movement), and a nice, even, tick.

It's a lot easier to see the effect of an escapement being out of beat on a pendulum clock. The principles are the same, but the parts are a lot bigger, and move slower! A pendulum clock that's in-beat will have an even tick - tock - tick - tock. Out of beat, it'll go tick-tock - tick-tock. If you lift up one side of a mantle clock, you can hear the beat change. By moving the case, you are altering the resting position of the pallets, same as moving the beat adjuster on a watch.

The other stud, which is further in towards the centre of the spring, doesn't grip the spring tightly. At rest, the spring doesn't actually touch anything on this stud. When the balance is moving, the spring spiral expands and contracts. It hits the stud in one direction, and a pin in the other. Moving this stud alters the effective length of the spring, and thus the rate. A shorter spring makes the balance "vibrate" faster, a longer spring makes it "vibrate" slower.


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## Chromejob (Jul 28, 2006)

I learned more in that last post than I have in a couple of weeks of reading DIY web pages ... thanks!


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## rambutan (May 7, 2010)

that's why this forum is so good - you can learn a lot from the guys who know


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