Hello,

I want to buy an Omega Seamaster 600 from a general web site. My problem is that I am not very sure the dial is a genuine one. Giving the serial number (~ 22.000.000), I understood that the watch was produced in 1965. Nevertheless, I saw that an Omega catalogue from that year did not mention any Seamster with numbers for 3, 6, 9 and 12, although my watch has such numbers. I asked a question to Omega official web site and they told me that they consider it is a genunie one, but they can not guarantee that since they didn t see the watch with their own eyes. The seller send to me some pictures, including the back case, which has 135.011 reference number. Unofortunately, I didn t find the meaning of such an algorithm, as I found the meaning for the eight figures on modern Omega watches only. Is there any possibility that an offical catalogue (1965) not to mention the enitre watch line ? I can understand that for the same movement (601 in my case) Omega can produce a wide range of dials,but to not find all models in that catalogue it looks odd to me. I don t want to buy a fake watch or a Franken one... I will attach some pictures. The price is 300 euros, which I think is a very low price for such a watch. Do you know what accuracy may have an Omega 601 movement in secondas per day ? If I will buy it, I have no problem to send it to repair to a local watchmaker.

Thank you very much,
Cristian

 

There have been discussions on this site about that. You may want to do a search.

 

Thank you. I have searched on the forum, but I couldn't find any relevant information. Could you help me with a link ?

 

No. I know for a fact that it was a recent discussion but it may not have been specifically referring to the 600. Perhaps another member knows the link.

 

The thread just surfaced. It is a constellation but everything else is similar. https://omegaforums.net/threads/con...-edit-it-has-arrived.54948/page-3#post-699408

 

Arabic numerals on a SM600 is not that uncommon
I have previously owned the one in the picture. Exact same font.

And have in mind that there were LOTS of different catalogues, so not finding your exact model in the catalogue for the production year, is not something to worry about.
The dial combinations were also endless, so the ones they show in the catalogue are just a few select ones.

The watch in question seems quite polished, and the gold plated ones aren't exactly in high demand. Cal. 601 and 135.011 (the reference number) is a definite match, so no worries there. 300 euros is not an outrageous price, but it all depends on whether it needs service or not. The 601 movement is a very reliable movement, if serviced properly

 

Hello again,

thank you all of you for quick answers. I just bought it. I will receive it in a week. Right now I am more calm giving all the informations I found from you and from Omega Co. Just one last question: if proper serviced do you know what is the accuracy of 601 movement in terms of seconds per day ? Is there any chance to be similar to a chronometer if the watch repair shop has enough patience to regulate it ? I find Omega Constellation a stellar watch but way to expensive for me for this very moment .

Thank you.

 

If the movement is in good condition and your watchmaker has some ability and patience, it's possible to get these to run virtually the same as a 561 Constellation chronometer. That's because the 601 train and escapement is virtually all 550 series parts as used in the 561.

But, it's not just a case of fiddling with the regulator...

Without checking, I think Omega call for a full wind variation on these of 25 seconds over 3 positions only. This can never be guaranteed to give you a constant rate close to zero in use as your hand can be in any one of six positions at any time and the other positions are not checked. A chronometer is tested in five positions and the last, 12H, is not usually checked as it's not a typical position for your hand.

First, you need it serviced well to get the best amplitude and that you don't have, in particular, any escapement faults plus it's set up in the best way possible. That might include hairspring adjustments, for example and in extreme cases dynamic poising.

Then your watchmaker tests at full wind in 5 positions (preferably 6) and get those within, say, a 12 second variation - for example, fastest rate could be dial up at +15 seconds per day and slowest might be crown down at +3 seconds per day. This would give you the same accuracy as a 561 Constellation but, you have to take isochronism into account and a 561 runs close to full wind a lot of the time because of it's auto winder. So, you need to be sure that it's still running in a good spec after 24 hours, again in 5 positions - you do this for a 561 as well just in case it's not on full wind. This will be far more than a typical service from many places, virtually all in fact as usually you see a dial up test only.

Having gone through all that, you wind it each day at the same time and wear it for a week or two, noting the variation and go back to your watchmaker who might then shave a few seconds per day off using the micro regulator.

It's an interesting exercise and not too bad if you're a watchmaker with time on your hands but, if you're paying it won't be cheap. Of course, if you really want accuracy on a budget, choose a quartz.

Hope this helps, Chris

 

Thank you for the link.

 

Thank you, Sir for this detailed answer. It will help me. It looks like a very interesting mechanism. I saw that 601 has been adjusted in the factory to two positions (I don t know which ones). Is it possible for a watchmaker to test it in five positions ? Giving the fact that Constellations is a chronometer, I thought that it has an accuracy of -4/+6 seconds per day. Maybe I just didn t understand very well the entire algorithm that you said.

I am not sure that I understood this mechanism: `but, you have to take isochronism into account and a 561 runs close to full wind a lot of the time because of it's auto winder. So, you need to be sure that it's still running in a good spec after 24 hours, again in 5 positions - you do this for a 561 as well just in case it's not on full wind.`. If I wind the watch everyday at quite the same time, is there a bigger probability to have an
isochronous balance wheel ?

I will make at least one time that test with a trusted watchmaker (whom I pay ), because I consider fine mechanics a lot more interested then quartz watches.

Best regards,
Cristian

 

Hi Cristian

Yes, your Watchmaker can test in as many positions as he wants to. I test in all six as I can leave the test running while doing something else. There also intermediate positions but they're not often used. It's the ability to run at a constant rate in any position that really defines a Chronometer.

It's not realistic to expect all fifty or sixty year old watches to run a COSC spec but a good one can be there if it's adjusted to be so with parts replaced as needed.

You test watches at full wind and full wind plus 24 hours. If you wind yours every morning then it will always be running in the same state of wind throughout the day so, you'll get more consistent results. The reason for this is that a watch running, say, +8 seconds in dial up at full wind might be running +16 or even +4 seconds after 24 hours. Sometimes they run more accurately at lesser wind but the explanation is quite complex. Your Watchmaker can average the rates and set the watch to run to its best during that day.

Isochronism basically is the ability of the watch to keep the same rate regardless of the swing of the balance - thinking of the balance as a pendulum, it doesn't matter if the pendulum swings through 2 degrees or 5 degrees, the elapsed time is almost the same. If it were exactly the same, it would be properly isochronous. In your watch, the equivalent is the swing of the balance being, say, 280 degrees at full wind and 240 degrees after 24 hours. So, as it's not perfectly isochronous, you get a small rate variation.

I hope you know your Watchmaker well as not many will want you to be this involved..... You're talking about a lot more work than many will do.

Cheers, Chris

 

Hi,

thank you for the explanation. Can I cheat by winding the watch at full wind let say two or three times per day in order to maintain the isochronism or such a maneuvre will be irrelevant during a day ? I don t know well my watchmaker. Another watchmaker told me about his superior skills and I saw that he has a much more elaborated shop. After what you have told me, I am little bit worried, because he told me that giving the fact the watch has been adjusted in two positions only, he will regulate it in those positions... To be more specifically, I let to him a Longines 370 movement (from 1964) to be CLA. For Omega Seamaster I will request a totally other approach as you have recommend me (five positions instead of two) even the cost will be higher.

Best regards,
Cristian

 

Hi Cristian

I wouldn't wind your watch more than once per day as you'll wear the seals out as well as putting unnecessary strain and wear on the keyless works.

Best option is give it to him and see what comes back. In answer to your original question, yes it may be possible to get this to Chronometer spec as it is very similar to a 561. If you're lucky, it may just fall there. If not, wear it and enjoy it as you don't need that accuracy anyway. To be fair he may need to do a lot of work and replace some parts to get it where you want so, it willbe expensive and he probably has too much work anyway.

Let us know how it turns out.

Regards, Chris

 

Hi,

yesterday I receive the watch and I will test it for a week as you said and I will post here the results, but fo now I must admit that I still have a few questions more like a general curiosity. If someone could help me. In order to maintain the isochronism is it possible to change the balance hairspring form an ordinary one to a Breguet overcoil ? From some web sites I understood that such an hairspring has the capacity to maintain an isochronism so the accuracy will be at its best. I am not sure if Breguet hairspring imply a particular design of the balance wheel, which an Omega 601 maybe does not has it. I must admit that I was thinking if it is possible to ask the watchmaker to change the old balance hairspring with an Breguet one (maybe mafe from Nivarox). From my third picture could you tell me if the balance wheel is made from glucydur ? I understand that this material is free from temperature changes that affect the accuracy.

Best regards,
Cristian

 

Hi Christian,

You cannot simply change the hairspring from a flat one to a Breguet one. Some series of caliber, such as Lip R 25 and Omega 30, could have a Breguet hairspring in some models and a flat one on others. But the balance would be different - typically a Breguet hairspring needs more space. And the 600 series only has a flat hairspring.

By the way, even if in theory a Breguet hairspring is supposed to have a better isochronism because it is always concentric, in practice you can have results as good with a flat one.

You may want to check the isochronism first - or as your watchmaker to test it. It could be good! If not, you could ask your watchmaker to work a bit more on the watch, but it could be expansive as Chris said. And at some point there is not much he will be able to do - except from changing the balance, which is usually expansive on those vintages.

 

Out of interest, Cristian, what accuracy are you hoping for? With careful resting in one or two positions overnight, it may be possible to tweak this to where you want it even if it's not Chronometer rated.

Regards, Chris

 

Hi,

I am sorry for my late answer. I was thinking to an accuracy like +/- 5 seconds per day. I have observed that my Omega gains something like 70-80 seconds per day so I took it to a watchmaker for a first fast checking. He has measured the watch with that tool that shows the average daily rate, the frequence and the amplitude of the balance wheel and the results after some 10 seconds were as follows: +75 seconds dial up and +37 seconds dial down. He told me that for an old movement, when I don t wear the watch it is better to keep the watch dial down. Nevertheless, I was very disappointed by this accuracy. The same watchmaker has repaired a Longines (370 caliber) so that it now has an accuracy of +7/+8 seconds per day. I hope that he can make a good job and in a month I will take my Omega to him for a proper CLA. My problem is that I don t know what to espect in terms of accuracy. He also yold me that the accuracy of 50 years old watch depends on many factors such as the quality and the frequence of the previous repairs (I don t know nothing about its history on this matter), if the movement has suffered from mechanical shocks. Is it correct what he told me on all the aforementioned matters ?

Thank you guys,
Cristian

 

You may be asking to much for an old watch. I mean, some watches can fit that accuracy, but depending on the condition of the movement, in particular if you do not change parts, it cannot be reached for every watch.

 

I never thoughut that a jewel can be such important for the final accuracy. Pretty interesting. Thank you. I will come back after the repair session.

 

Hi,

I have a question related to the accuracy. Maybe is a silly question, but I will take my chance . I am refering to the 3rd picture from above, the one with the Omega movement. Is it possible to adjuste the accuracy by the regulator like it can be done with a Bosley regulator by simply moving it with a finger nail or a small tool ? I am not sure if the regulator from Omega is a Bosley one, because I saw that my regulator has a screw in it. Strangely, the regulator does not have any fast-slow scale. I am wondering if it is safe to try by myself to regulate it according to the aforementioned means. My watch has +75 seconds per day in dial up position so I was thinking if I can try succesfully to correct that rate. I am taking it more like a try-error method. Nevertheless, if there is a risk to damage the movement, I will not take play the game. What do you think ?