Seiko’s first swim-friendly watches were Cronos Seahorse in 1960. In 1962 the Cronos replaced seahorse with water 50 proof. This watch is in good condition, but can do with a service.
I dig the Seiko balance bridge construction! Movement looks very good.
Broken setting lever spring… Good news is I have found some in Japan.
I take the setting/winding mechanism apart.
Seiko did not save on the amount of jewels in this movement…
The only marking I find to indicate calibre name is T40?
Movement almost apart.
The old mainspring looks pretty good.
I have cleaned the movement and here I see that the balance moves freely after fitting the shock jewels.
Mainspring has been cleaned, oiled and put back into the barrel.
The barrel and centre wheel goes back in place.
Here you can see the gear train layout before fitting the bridge.
I like the colouring of the lettering.
The new setting lever spring.
Setting/winding mechanism back in place with the new setting lever spring.
The movement is almost back together.
I fit the balance and the movement is running.
The result is very good!
Dial and hands go back onto the movement.
I take the case apart and clean it.
I use a NOS crystal.
Movement goes into the case, looking great!
Awesome watch.
This I would consider a genuine sports watch:)
6 Responses to Seiko Cronos 50M calibre : 54-00-2
Great post Mitka – i had to work on an FHF 72 a couple of weeks ago and was struck reading today’s entry how structurally similar the movements are: http://17jewels.info/movements-en/movements-f-en/movements-f-fhf-en/770-fhf-72.html
Interesting observation!:)
Nice Balance bridge! Too bad you cannot set the beat error the easy way, though!
Yes it’s a bit of a hit and miss operation;)
Dear Mitka, I hope you’re well.
For your information, the calibre number of the non-date Cronos movement is 54-00-2 (or 5400 or 54A in Seiko’s newer movement numbering system), and the calibre number for the early (pre-760/850/760x) Seiko Champion movement that you also serviced is 54-20-1 (or I would guess 5420 or 5420A in Seiko’s newer movement numbering system), as seen here: https://www.tapatalk.com/groups/seikoholicssupportforum/an-old-post-about-caliber-numbers-t381.html
People often call the early (pre-760/850/760x) Seiko Champion movements (and the first-generation, non-hacking King Seiko movement 54-40-1) “un-numbered”, since these numbers are not widely known.
Thank you for the info! Interesting stuff