Early Omega Cal. 561 (1959) - "24 JEWELS" Automatic Bridge

Hello everyone,

My name is Alessandro, and I run an Italian business specializing in Omega watches.

I have been researching vintage Omega watches for many years, but this early Constellation has raised a question that I have not been able to answer, despite quite extensive research.

The watch is an:

Omega Constellation Chronometer
Ref. 14393-61 SC
Calibre 561
Serial 17.42xxxx (approximately 1959)

The watch has just been fully serviced by an Official Omega Service Centre, so I have no reason to question the movement itself. My goal is simply to understand a historical detail so that I can document the watch accurately for future collectors and clients.

After comparing many Cal. 561 movements, I noticed two details.

1) Automatic winding bridge

The automatic bridge is engraved only:

"24 JEWELS"

It does not carry the usual inscription:

"ADJUSTED FIVE (5) POSITIONS AND TEMPERATURE"

that seems to appear on almost every Cal. 561 I have been able to find.

2) Rotor retaining screw

The rotor retaining screw also appears slightly different from many later examples.

I have already searched Omega Forums, old technical documentation and several online archives.

I found discussions confirming that the automatic bridges of the 55x family were available separately from Omega and could be replaced during service, but I have not been able to find another Cal. 561 bridge engraved only "24 JEWELS".

My questions are therefore:

Could this be an early production variation from 1959?
Could it be an original Omega service replacement bridge supplied later?
Does the rotor screw appear correct for an early Cal. 561?

The movement appears remarkably coherent throughout:

identical copper colour across all bridges
identical ageing and finish
no obvious mismatch between components

Since it has just been serviced by an Official Omega Service Centre, I assume that the movement was considered mechanically correct, which makes this even more interesting from a historical perspective.

I have attached:

photographs of the complete watch
movement photographs
inside caseback photograph

I would especially appreciate the opinion of @Archer, but I would be grateful for any thoughts from members who own or have serviced very early Cal. 561 movements.

Many thanks in advance for your time.

Alessandro

From the photos, it appears to me that likely the entire automatic module was replaced at some point, likely as a complete unit. The rotor has the "O" on it, indicating that it is a later replacement part.

The gib screw looks fine to me.

Thank you very much for your reply, Archer.

That is extremely helpful.

May I ask one additional question?

When you mention the "O" on the rotor indicating a later replacement part, are you referring to an official Omega service replacement introduced at a later date?

Also, would it be reasonable to assume that the complete automatic module (bridge, rotor and automatic winding components) was replaced together during an official Omega service, rather than individual parts being mixed?

Many thanks again for sharing your knowledge.

Yes, if you were to purchase a new rotor today, it would have the "O" on it.

If you look for early literature on these movements, one of the features they advertised was that the entire automatic winding system could be replaced as a unit - this was to save watchmakers time, and I believe back then you could send the old unit back for credit.

Was this one replaced as a whole unit? No one can say for sure, but given that the colour of the bridge and new rotor seem to match, and are quite different from the rest of the movement, I wo7uld say it's likely.

Thank you very much, Archer.


Your explanation is extremely helpful and makes perfect sense. I really appreciate you taking the time to share both your experience and the historical background regarding Omega's service procedures.


It has been invaluable in helping me better understand this early Cal. 561 and accurately document the watch.


Thanks again for your time and expertise.
Alessandro

Thank you for your observation.


The movement serial is actually 17,7277** (I've omitted the last two digits for privacy), so you're absolutely right that it's in the 17.7 million range.


Thank you!