Service: Omega Speedmaster 175.0043 calibre 1155 (Valjoux 7750)

IMG_0638Between 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.IMG_0641

Omega “branded” this movement as the 1155, but its a standard ETA7750, and the ETA stamp is still there under the balance.IMG_0644

Very nice looking dial – and of course a give-away for the 7750 beneath.IMG_0645

One of the pushers has broken off, and I will replace both.IMG_0646

The pushers are push-fit (not screwed).IMG_0647

The bottom plate. This movement is also available with a day ring, and the space for the day wheel changer is there.IMG_0648

I start off with the top plate.IMG_0650

With the rotor removed, a full look of the movement.IMG_0652

The chronograph bridge is off. IMG_0662

Stripped to the base movement.IMG_0665

The gear train. At the right, you can see the ETA stamp.IMG_0669

Now it’s time for the bottom plate.IMG_0671

The hour recorder at 1 o’clock of the photo.IMG_0725

The new pushers have arrived.IMG_0745

All the parts have gone through the cleaning machine.IMG_0746

And no lack of them 😉IMG_0747

The new mainspring goes into the barrel.IMG_0748

Then I put the balance jewels back in.IMG_0749

The gear train and hacking second lever are in, and I can put the bridge on.IMG_0751

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….IMG_0752

And this is what I meant when I said that the 7750 is a great performer.IMG_0755

Now I can put the chronograph back together.IMG_0757

The bottom plate is ready for its bridge.IMG_0758

Now only the day ring is missing.IMG_0760

And we’re ready for the dial.IMG_0762

Dial and hands go back on.IMG_0763

The paint on the tachymetre ring has come off.IMG_0764

To restore it, I apply paint more generously than needed, and let it dry for a couple of hours.IMG_0770

Now I can remove the excess with a piece of pegwood, and I have nice and clear black numbers and markers again.IMG_0780

I case the movement.IMG_0781

And put the rotor back on.IMG_0783

Yes, that’s very nice indeed.IMG_0784I love the look of this Omega Speedmaster.


31 thoughts on “Service: Omega Speedmaster 175.0043 calibre 1155 (Valjoux 7750)

  1. Hi
    I have lost mine crown of my watch(same model like here) and i cant find it any where. Can you help me with this? Thank

  2. I have just bought a second hand Omega Speedmaster Automatic Date circa 1991.

    My Watchmaker of 18 years had “concerns” with the watch’s movement. I went to Omega’s WA Service Agent who shares the same concerns but whilst both thought the movement was fake both said only Omega SA could verify this with a search of the Archives. This article referenced the cheapest movement ever used by Omega and both watchmakers said this was/is a possibility.

    Standout concerns which led them to question the authenticity of the movement:

    1. Automatic bridge is not jewelled.

    2. No Etachron adjuster on balance bridge.

    Is this consistent with the movement as reviewed by

  3. I have a similar model but with leather strap. I wanna put it on a steel bracelet. Where can I source for the original bracelet? Can you assist? TQ

  4. Have the same, it orignally had a blue leathe wisband which I changed, n use a nylon one. It’s lesssmelly.some years ago it lost ime a lot so I sent it on vacation to Switzerland. Since then it works perfectly. I just love the chrystal glass. After 27 years not the slightest scratch on it. It’s just a good life companion.

  5. Pingback: Why did you choose a watch with a high-end ETA movement over In-house? - Page 11

  6. Hi,

    I got the same watch as you. It’s a very lovely watch. However, may I know what you use to repaint the marking on the bezel? And what you do to remove the excess paint?

    Please advise.

    Thank you

  7. I live in NYC and have a much loved but well beaten Omega Speedmaster 175.0043 calibre 1155. I have recently had a cycle accident and smashed the crystal, it also needs a service as its been loosing time. I have had very bad luck with trust worthy repair shops in NYC, do you work on watches from overseas? If not can you recomend a reputable omega specialist here?
    Thank you in advance.

  8. This is just fantastic! I recently acquired one of these from another watch forum member and the numbers were worn just like these. I will have to try the black model paint trick one upcoming weekend. Thanks!


  9. Hi Christian,

    The lift angle is 49° so the amplitude is probably around 280°
    Didn’t this one suffer from a worn out rotor bearing?
    It looks like the rotor has scraped along the case back.

    Kind regards,

  10. Of all the watches I’ve read about on your blog, if I understand things correctly, this one performs better than all of them. I’ve seen and heard of the 7750s phenomenal performance, stability, and durability in many places over time. For those reasons, I really want to add a watch with a 7750 at some point. I’m okay with it being unattractive if it performs so well. The only thing I’m unsure of is the unidirectional winding and subsequent fast spinning in the opposite direction. It might not even be an issue that bothers me, but I have not yet experienced it so don’t really know.

    • Yes, this is the best performing chronograph, and it’s just as good as the Omega 1140, which is an ETA 2892A2 with a Dubois-Depraz module on top. Not only a good work horse, but a great performer!

  11. You did a great job… OMEGA Speedmaster is one of the best watch… with this work is back to work and got back the value.

  12. What paint did you use to paint the tachymeter? My watch has also lost its colour and im wondering what should i use to get good finish.

  13. Hey Christian! Hope you are well mate. Now I had make a comment with you picking on one of my favourite movements to work on. 😉

    Yes the click looks like it came from a cheap $5 movement, but most modern watches out there have cheap wire springs somewhere in them, at least at this price level. Now I’ve serviced Pateks and Vacherons, and even some vintage Longines that had nicely machined clicks, but those were very high end movements. Of course anything with a Geneva seal is not allowed to have wire springs, but again those are not at the price level of this Omega.

    I’ve said it before and I’ll say it again here – the 7750, in all it’s guises, is one of the most accurate and reliable movements I service. And when I say that I mean that they need no real extra tweaking to make them run well. Unlike many movements where I have to do things like dynamic poising to get the positional variation I want, on a 7750 chronometer say from Omega, they call for 12 seconds Delta over 5 positions at full wind, and I can usually get 6 seconds or less over 6 positions, all with just the normal hairspring work that gets done on every watch. And with the ETACHRON, it’s almost child’s play.

    I know this movement seems to have a reputation for being tricky to service, but I have never found it so, and I’ve probably serviced every stock version of this (plus some that have been heavily modified) and they all go smoothly – I always look forward to having one on my bench – I know there will be no surprises.

    I think the only real knock you can make about the 7750 is that it’s common. But it’s common for a reason – it’s good at what it does.

    Anyway, glad to see you taking on someone and passing on the craft.

    Cheers, Al

    • Hi Al,

      I’m absolutely with you there, and I said that in the post as well. The performance of the 7750 is great, and that includes the positional variation.

      Maybe I’m a bit too picky, but that one wire spring for the click just bothers me 😉

      Glad to hear from you again!


  14. I have an Oris with a 7750 – it’s my most accurate watch, loses about 1 second a week in normal wear. I’m afraid to get it serviced !!

  15. Nice one, Christian!

    Apart from the subdial positions, another giveaway of the 7750 is the shape of the rotor. Any technical reason it’s that distinctive pie-shape?

    • You don’t really want any rotor mass past the 180 degrees that are taken up already, and you need a bit of material for the bearing, so this shape is easy to make and effective.

  16. I’ve read the Valjoux 7750 can be tricky to service!?
    Its been around a long time though so they must have done something right with it!
    I only own one watch with the movement and it is very reliable and keeps excellent time. Also lets not consider this a “cheap” movement! There’s no “cheap” watches with the 7750 inside. If there are please let me know! 😉

    • It is indeed a bit tricky to put back together, and this one had lots of scratches from someone not being too successful at doing so.

      I only meant to say that this is the cheapest Swiss chronograph movement widely used, not that it’s a cheap movement.

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