Today I am featuring this Speedmaster 1750032.1. It is the little cousin of the Speedmaster professional “Moonwatch”. It is similar in appearance, but slightly smaller at 39mm in diameter, which earned it its nickname “reduced”. It is however functionally very different, being an automatic watch rather than a manual wind: it is powered by Omega’s calibre 3220, which is based on an ETA 2892 ebauche with a Dubois Depraz Chronograph module.
The watch came in a very sorry condition, missing its stem and a pusher. I was expecting a replacement of the missing parts and a straightforward service. It turned out to be a very challenging project indeed.
I start by opening the case, revealing a beautifully decorated Calibre 3220. It all looks good so far. The broken stem is still in there, and was fairly easy to extract.
I remove the oscillating weight and automatic framework, and still no cause for concern.
It is not until I remove the movement from the case that things take a turn for the worse. There are signs of corrosion, caused by water ingress through a pusher. Thankfully, the dial is only very lightly stained on its edge.
I remove the dial, and there is further evidence of water ingress, but only surface rust here so this will clean up easily.
This is the Dubois Depraz module seen from the other side. Worryingly I am not able to press the reset pusher, it is completely seized. I start the service with the Chronograph module, as I am curious to see if I can get it back up and running.
I remove the plate, and things are looking pretty grim.
I eventually have the whole module stripped down.
I carefully inspect all the parts, and quarantine the ones affected by rust. I remove the rust with a fibre glass pen.
I soak the parts in acetic acid to kill the rust.
I am pleased to report that all the affected parts were salvageable. Thankfully the oxidation was very localised, and did not affect any pivots or wheels or other very sensitive parts.
After cleaning all the parts ultrasonically, I start re-assembling the Chronograph module.
Some of the parts are slightly stained, but critically there is no rust left, and the affected parts are perfectly functional.
I fast forward many steps ahead here, and here we are with the Dubois Depraz module fully assembled and working.
I then move on to the main movement, which is the power source for the chronograph. It is based on a conventional ETA 2892 movement. I start with the bottom plate, and remove the keyless work. Obviously no calendar work as would typically be found on the 2892.
I strip down the automatic works, and the click / winding mechanism.
And eventually I have the movement fully disassembled.
After ultrasonic clean of the parts, I rebuild it as usual, starting with the mainspring.
The barrel is installed with the intermediate wheel under the barrel bridge. On this movement, the ratchet wheel, intermediate ratchet wheel and driving wheel, crown wheel and click mechanism are located under the barrel bridge.
I then place the train wheels in their respective pivot holes, and secure them with the train bridge.
All is well so far, so I am going to rebuild the keyless work as I want to be able to wind the movement to test it. For this I need to fit the new Omega stem and crown.
They will only be tentatively assembled for now, as I will shorten the stem to the correct size later when the movement is back in its case. I can then assemble the keyless work.
After assembling the escapement and lubrication the movement is performing very well, with an amplitude well in excess of 300 degrees. This is a good job as the Dubois Depraz module puts a lot of load on the movement, and will create a small drop in amplitude.
I can now finish the assembly of the movement, with the automatic works and oscillating weight. I will fit this last when the movement is in the case.
The Chronograph module is bolted on the the “power source” movement. I can now fit the dial and hands. There was oxidation on the edge of the dial but it cleaned up well.
At this stage, I need to turn my attention to the case before I can progress further. The case had surface rust, but it cleaned up easily.
I completely strip the case, removing crystal and bezel. The old pushers are pressed out.
And I can fit the new Omega pushers.
The armoured crystal is polished. It is only lightly scratched, and, as it is the original Hesalite crystal with the tiny Omega logo in the middle, it is definitely worth the effort to save it.
Crystal and bezel are re-assembled with a press.
The movement can now be re-cased, not forgetting the all important stop lever which fits under the automatic device framework on this movement.
The case and movement are now re-assembled and everything is working as it should.
Finally, I refinish the bracelet, with a mirror finish on the centre links and a brushed finish on the clasp and outer links.
The service and repair is now complete. The Dubois Depraz module is not the easiest movement to work with, but the real challenge on this project has been what was lurking underneath. It certainly was worth it as the watch looks great again, and it runs perfectly.