1956 Omega Seamaster 501 or is it ? rotor and case back look to be engraved not stamped (were they all stamped or engraved) no 501 logo on movement dial most likely a repaint that's okay crown maybe okay crystal has omega logo serial number dates to 1956 what do you think regards Gary

 

Looks like a 501 to me. For some reason Omega didn't engrave the caliber on all 501s as I've seen a few without the caliber marking.

 

Here is a 501 from bidfun. you can see the cal.# is on a part that is half shown in your pics. Jim is probably right.

 

Jim I couldn't find one other example of a 501 movement or watch online that wasn't signed I would love to see a photo if someone has one maybe the bridge is off a 501 constellation is that possible as some of there bridges are unsigned

 

Here is a better photo of bridge note no 501 cal

 

I can't seem to get on to any overseas sites at the moment, but just Google Omega 501 movement and go to images. There's a few there.

 

looked at hundreds of 501 movements couldn't find one that didn't have either 501 stamped on or next to bridge and shouldn't case info inside case back be stamped not engraved Gary

 

Well I just Googled "Omega 501 movement" and found two in the first five or so images.



As to case engraving v stamping, I can't tell from the photos but it all looks genuine to me.

 

It wouldn't bother me too much. Both my 501s have the mark and it certainly is unusual for an Omega but the movement clearly is a 501 and doesn't look to have been messed about. It too think the caseback marks are nothing out the ordinary either. I agree that it has likely been redialed and the second hand is suspect but as you say its still an attractive piece.

 

The first photo might say 501 but is a different bridge second photo the bridge is behind rotor better luck next time regards

 

You're not happy with the service being provided here, are you?
From the google results I see, some 501 have both the Omega symbol and the 501 inscribed on the third wheel bridge (let's call it version 1) some only the Omega symbol (version 2). Version 1s have a bare auto winder plate. Version 2s usually have the 501 inscribed on the auto winder (along with another Omega). So in your case one of the two bridges may have been swapped with the other version at service. It's still a 501.

 

My apologies, I thought you were talking about the Ω symbol without a caliber beneath it.

e.g.:



As the 500 family is based on the original 470 it's entirely possible that replacement or service bridges were not engraved due to them being used for a number of calibers.

 

Hi aprax was the first part of your post a rhetorical question?( I love watch forums ) thanks that's what I expected one of the two bridges may have been swapped out can you help with the engraving question some early (inside )case backs and rotors look stamped and some engraved the serial number dates watch to 1956 the inner case marks I think 1956 what year were 501 cal movements released some say 1956 same say 1960 thank's for your post

 

Hi jim yes I have owned a 470 seamaster and a 471 both nice watches very plausible answer thanks

 

Omega AJTT dates the 501 introduction to 1955 (19 Jewels) and 1957 (20 Jewels).

 

so that means the 20j rotor is a replacement as the movement serial number is 1956

 

Have just checked, you could be right, here is my 15.04m serial 501 with 19J, my 15.65m has 20J. Not conclusive since my serials bracket yours.

 

According to my references, the 15 mil serials started in 1956, but with many other models being fitted with various movements at the time, an absolute date of 1956 is tenuous.

My charts show that 15 mil serials were used up to 1962 in low production models. So your watch could easily be a 1957 production.

Although after all this time, the only sure answer is to request an Extract of the Archives from Omega.

 

my serial number is m 15.2 and 20j