Oiling Dubois Depraz chrono module pivots (Omega Speedmaster Reduced)

[Simeon]

I have been recently servicing an Omega 3220A chronograph movement which uses a Dubois Depraz 2000 chrono module.  This has been quite a time consuming project, not necessarily difficult but with lots of steps.  Working on the chrono module is like working on the love child of a hugely complex keyless works and a Timex pin pallet movement. I do have access to a couple of Omega tech sheets and a couple of relevant Youtube videos (including Mark Lovick's Breitling series) so I feel confident that I have all of the required information.

The 'tractor' movement (effectively an ETA 2892) had no issues with obtaining 300 degree amplitude dial up / dial down and maybe a spread of 7 seconds across all of the positions.  I serviced the chrono module and when reinstalling it, this brought the amplitude down to about 260 degress with the chrono stopped and 200 with it running.  The Omega specification states that the chrono running should see the amplitude drop by no more than 40 degrees (from, I am guessing, the assembled amplitude i.e. chrono stopped rather than just the bare tractor movement).

Obviously this isn't good enough. I am going to have to redo the chrono module again.  Where I suspect I have a problem is inconsistent / over oiling of pivots.  For some reason the Omega technical guide states to apply oil to the bottom pivot of each wheel and then place in the jeweled base plate.  In practice, I managed to smear oil on the horizontal base of the wheel which would be smeared over the outside face of the jewel.  This also wouldn't be helped by dragging the wheel around trying to get the lower pivots to engage in the the jewel.  When I watch Mark service a similar Breitling chrono with DD module, he also oils the bottom pivots and installs the wheels (obviously doing a better job than me!). 

My question is, why can't I install the wheels dry and the oil the jewel on the other side of the base plate in the conventional way? The top pivots are oiled through the jewels in the conventional way, so why would the lower pivots be any different? Looking at the those jewels (picture below an example from a different movement) it looks like there isn't an oil well in the outside surface of the jewel around the pivot, so perhaps I would be better applying a drop of oil directly to the jewel hole before installing the wheel?  Perhaps the jewels have different arrangement to conventional jewels because the outside face is installed against the dial side of the tractor movement and we don't want to risk oil migrating from the module to the movement.

There are also a couple of friction springs that may have an impact on amplitude, I will recheck their pre-load but these should be OK.  Is there anything else I should look at as a source of friction in the DD module?

[SwissSeiko]

Ahh the DD modules. I havent done one of these for about a year, but when I did it, I followed the service guide and got it within spec. Do you have this? Ive attached it for you and any others who might need it.Omega 1140.pdf

[JohnR725]

On 4/15/2025 at 9:37 PM, Simeon said:

For some reason the Omega technical guide states to apply oil to the bottom pivot of each wheel and then place in the jeweled base plate.

a unfortunate problem of watchmakers is watch companies not explaining why they do things.

the practice of oiling the pivots is not unique to all watches. I've seen it on Seiko watches for instance a lot of the quartz watches you'll do that because you can't see the pivot on the other side there is no oil sink. Or some other watches they actually use grease rather than a oil and they do say that the grease won't flow if you oil in the jewel you have to put it on the pivot

the other reason for all of this may be that if you look at the side view this is really thin module and the one side presses against the other watch movement and if you were to put oil in oil sinks they may be concerned that the oil is going to run down into the other module. So they may only want the oil sparingly placed on the pivots and not flooding all over the universe but that's a speculation

 

 

[Simeon]

So, looking at my own module, I can see that there are actually oil sinks on the outside of the jewels. I am going to apply oil in the conventional manner and see how it goes.

On 4/19/2025 at 12:38 AM, SwissSeiko said:

Ahh the DD modules. I havent done one of these for about a year, but when I did it, I followed the service guide and got it within spec. Do you have this? Ive attached it for you and any others who might need it.Omega 1140.pdf

Actually, this is interesting. A third version of a service guide for this movement. I did learn that the 0.6mm 'gauge' for measuring the chrono second wheel depth is actually a screwdriver tip (this is sensible, the others just show this as a cylinder shape so I used a micro drill tip). It also provides minimum amplitude for the base movement in horizontal and vertical positions and vertical positions, after 24h with the chrono running.