Quick question about my omega 2531.80 I’m not 100% sure of the date of production ( serial#6010) but I’ve been doing some research, and apparently the earlier smp had the 1109 as compared to the newer 1120. Is there a way to tell which one mine has? What are the differences between the two? Is one better then the other? I’d appreciate any help with this.

 

To the best of my knowledge the only way to tell is by taking off the case back.

 

The 1109 had problems with the auto winding so for the 1120 Omega completely changed the profile of the rotor to make it heavier and more efficient. The case number will tell you nothing. Nurseford is right , you need to take the case back off to see the calibre number on the rotor.

 

Thanks for the help! Are there any other differences other that? Say the Nivarox hairspring? I wouldn’t say the 1120 could possibly be more accurate as mine is running +2 seconds a day at the most. I’m just a little bit crazy when it comes to movements so I was somewhat disappointed when I found out mine seamaster may not have as good a movement as others.

 

If you have a 60m serial then you likely have a 1120. The 1109s were very early, around 1994 and only used briefly so at a guess would be about 54-56m serials. 60.1m is likely around 1997 in my experience. Yours maybe a tritium dial as it is around the change over but all the luminova dial 2531s came with 1120s. I had a 60.2 serial Bond from 1997 with a 1120 if that helps, given the proximity of numbers, I doubt yours is 3 years older which it would need to be for a 1109 movement.

 

Ok thanks yes that certainly helps. Mine actually does have a tritium dial but if the early ones were in the 50 range then I would assume mine is an 1120 thanks for your help.

 

I also had a 60.3m serial 2254 SMP, a model introduced with luminova dial in late 1997 with 1120 movement so that gives you another close datapoint.

 

I've had a few 1109 SMPs, all of them would had weird date discrepancies and would map to the 1980s if you use the online unofficial serial number tables i.e. 48M to 53M.

So, screwing off the case you'll know for sure. But unusually low serial number is also a very good hint.

 

I have a 2531 with 1109 caliber inside. The watch is 54M serial , has been sold at the end of 1993, is a "no cosc" dial.
It runs like the brother with 1120 ( serial 496... sold in 1996) ....and the cousins with 2500 and 8500
immagini internet

 

I thought I had seen everything SMP related but I didn't know the first ones weren't marked up as Chronometers, quite a rarity I should think. I did a double take in case that is a dial swap with a quartz but it can't be as the date window is in a different place on those. It is comforting to note that my theory that the hands rarely match the dial colour on tritium SMPs is born out here, the hands are usually slightly greener and lighter than the dial lume.

 

Right, the quartz dial is different.
I can confirm that the tritium on the hands change colour ( always greener) in a diffrent way respect of index ( yellow - creme)

 

No not all of these were COSC rated. This model is a 25318600, so slightly different than the 25318000. Description for the dial:

DIAL BLUE PT.LUM.WITHO.CHRO. = without chronometer...

Cheers, Al

 

I read a story a while back that there was initially such a demand for the SMP300 that in order to fulfill the demand, Omega used movements that did not go through COSC certification. Could be apocryphal

 

What happens to movements that do not pass/not tested COSC certification? Does an 1120 movement become.. some other movement? A non-COSC 1120 movement? Thrown away?

 

First, I suspect very few would not pass when they are submitted - the 1120 is very capable of meeting COSC specs.

I would guess that the few that didn't make it would be reworked and submitted again.

 

My hands are also slightly more faded than the indices. At first it bothered me but then I also noticed that most of the 2531’s look this way. Theory confirmed.

 

Yes this is well documented. Every tritium dialed SMP I've had in, be it time and date only as above or SMP chronograph, has been this way.

 

Does calibers 1109 and 1120 use the same mainspring? Have been trying to find out the correct mainspring for caliber 1109 and OFREI does not list it anymore, Cousins lists a generic GR25341X (1.05 x .115 x 420 x 10.5) but wonder if the original Omega part is still available

 

Yes

 

Thanks Al, is the part number from Omega OME1120771