Reply With QuoteIf there's one thing I do when I haven't worn a watch for a while it's move the date forward a day using the crown before I wind it.
Personally I've never had a problem but I know a few who have.
Sent from a technical device.
Hopefully all owners of Valjoux 7750-powered watches are aware of the need to avoid using the quickset date function when the hands are between approx. 21:00 and 03:00 and the risk of damage if a determined attempt is made to do so. Here's why:
host an image
To the left of the 17 is the wheel that drives the date wheel when the quickset is actuated. As the crown is turned in the quickset position the wheel engages with the date wheel teeth to drive the date wheel forward. When the pressure on the crown is released this wheel springs back out of engagement. The date jumper (engaged at 31) enables the wheel to 'jump' in 1 day increments when either the quickset is actuated or during normal running of the watch at midnight (ish).
The brass coloured wheel at 23 drives the date wheel forward during normal operation of the watch or when the hands are set manually. This pic shows the position after the date has just turned over , the wheel has turned clockwise to engage with the date wheel, this would equate to around midnight. It can clearly be seen that the pointer is still engaged between the 27 and 28 positions and if an attempt to use the quickset was made the date wheel would be unable to move freely. If the crown is forced the date wheel teeth will invariably be damaged or the wheel driving the date will suffer. Either way it's a repair situation!
As the time moves forward to around 03:00 the pointer becomes free of the date wheel and the quickset can now be used safely. The pointer is now at 30 and is just clear of the date wheel teeth. In the next picture I`ve turned the crown in the quickset position thus causing the driving wheel to engage.
If setting the watch after it has stopped the sensible precaution is to wind the hands manually until the date steps forward and continue winding to around 04:00 before using the quickset. If any abnormal resistance is felt when setting the date do not try to overcome it!
If there's one thing I do when I haven't worn a watch for a while it's move the date forward a day using the crown before I wind it.
Personally I've never had a problem but I know a few who have.
Sent from a technical device.
Thank's for a very informative write up regarding when NOT to adjust the quickset date Paul. I knew when not to prior to this and that the date wheel teeth could be damaged, but not technically why, only that they could. Now I know, great explanation.
Best Regards - Peter
I'd hate to be with you when you're on your own.
Knew about that issue, but adding to the theoretical knowledge some actual live pics of the mechanism to properly understand what is going on in the movement is very helpful, thank you!
Thanks for that, I have been moving the hands past midnight and date change and on to 05:30am before using the quick set date for many years now. This is the best graphic explanation I have seen for this problem.
Bit of a flaw tbh , the Chinese clone 7750 movement have addressed this problem as posted here by the watch guy
https://watchguy.co.uk/valjoux-7750-...hange-feature/
Crazy to think the Chinese have improved on something instead of poor quality reproductions they are known for
I’m aware of the modification implemented in some of the Chinese clones, a similar design is used on other movements to safeguard against this issue, and it does beg the question why the design wasn’t modified years ago!
The Valjoux 7750 is hugely underrated in my opinion, but this us a weakness. The overall excessive thickness of the movement and the self- winding that only operates in one direction of the rotor are other weaknesses, but apart from that they’re excellent.
Winding in a single direction is often seen as a weakness / less desirable in auto movements, yes it can cause that wobble, but I would like to know of any other areas this could cause an issue? I presume less efficient winding, the unnerving wobble that soon becomes forgotten.Originally Posted by walkerwek1958
I agree the 7750 is an underrated movement, yes it’s thick but the base movement can be modified to do a whole host of things and in some ways it saved the mechanical watch business, virtually everyone used it or a version of it when mechanical watches became popular again, before ‘in house’ became a thing.
I have several watches with the movement and they are all accurate, robust watches, I have never had an issue with a 7750, the same cannot be said of other movements.
My first ‘proper’ watch was a Tag Heure Carrera which had a modified version of a 7750 in it. As others have said it was thick, heavy and had the rotor wobble. However due to it being my only good watch I wore it permanently and subjected it to all sorts of abuse. Mountain biking, running, DIY, outdoor sports.
It never failed me and never missed a beat.
Sent from my iPhone using TZ-UK mobile app
If the auto-winding design was modified to enable the watch to wind in both directions of rotor movement it would be better, the wobble would be eliminated too. However, to do this would probably make the movement even thicker, there isn`t room for a second reverser.
Generally I find these movements respond very well to straightforward servicing, can`t recall ever having problems with the balance, and they always give excellent amplitude. Despite not being COSC rated I usually find the positional agreement is within COSC range. A 7750 in good health only drops 10°-15° with the chrono running too, although this will deteriorate slightly after a few years of regular use. A poorly example will give around 230-240° and drop to 200 with the chrono running, but that's general when the watch hasn`t been serviced for 10 years.
Posting Permissions