Between the 861/1861 and the newer ETA/Dubois-Depraz movements, Omega used the ETA (Valjoux) 7750 for a while. This is the lowest end chronograph movement the Swiss watch industry has on offer, with a unidirectional winder and a click spring construction that is slightly dubious 😉 Nevertheless a popular movement, and you can find it in many Breitlings, TAGs, and other Swiss watches.
You can tell from the outside by the sub-dial configuration. The 7750 has the sub-dials at 6,9 and 12 o’clock. There are variations available where the sub-dials are in other configurations, but these modifications tend to be problematic.With all the moaning done, I have to say that the 7750 is a great performer. It beats at 28,800 b.p.h. and has a very steady beat rate, even when taken to different positions.
This Speedy looks great, and I very much like the dial and case design. The bezel has a tachymetre scale on it, and the black paint has come off parts of that.
Omega “branded” this movement as the 1155, but its a standard ETA7750, and the ETA stamp is still there under the balance.
Very nice looking dial – and of course a give-away for the 7750 beneath.
One of the pushers has broken off, and I will replace both.
The pushers are push-fit (not screwed).
The bottom plate. This movement is also available with a day ring, and the space for the day wheel changer is there.
I start off with the top plate.
With the rotor removed, a full look of the movement.
The chronograph bridge is off.
Stripped to the base movement.
The gear train. At the right, you can see the ETA stamp.
Now it’s time for the bottom plate.
The hour recorder at 1 o’clock of the photo.
The new pushers have arrived.
All the parts have gone through the cleaning machine.
And no lack of them 😉
The new mainspring goes into the barrel.
Then I put the balance jewels back in.
The gear train and hacking second lever are in, and I can put the bridge on.
The base movement is back together. Have a look at the click / click spring construction. That gets me every time. The Chinese do this sort of stuff in their £5 movements….
And this is what I meant when I said that the 7750 is a great performer.
Now I can put the chronograph back together.
The bottom plate is ready for its bridge.
Now only the day ring is missing.
And we’re ready for the dial.
Dial and hands go back on.
The paint on the tachymetre ring has come off.
To restore it, I apply paint more generously than needed, and let it dry for a couple of hours.
Now I can remove the excess with a piece of pegwood, and I have nice and clear black numbers and markers again.
I case the movement.
And put the rotor back on.
Yes, that’s very nice indeed.I love the look of this Omega Speedmaster.