OMEGA SA  WORLD SERVICE ORGANIZATION   GT-19-C-013-E - C - 1538
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General information for calibre 1538 
Seconds wheel
Version 1538A Version 1538B
Former execution New execution 
7221441227 7221538B30027*
 
Improve the accuracy of
the seconds hand jump.
Ref. 7221538B300273
New version from date code: 47/04
Wheel train bridge
Version 1538A Version 1538B
Former execution New execution 
7221538B1004807 7221538B1004807
A magnet to stabilise the
seconds wheel has been added.
New version from date code: 10/04
Improvement of the seconds jumps on calibre 1538D 
In order to better meet our customers requirements, the jump 
of the seconds hand on calibre 1538D has been further 
improved.
Technical modifi cations on version «D» 
Calibre 1538D
Application :
When repairing a version D, the new components must be 
used systematically.
When ordering one of the two components individually, an 
automated order of KIT ref. 7221530D9999* is issued. 
It comprises:
Seconds wheel ref.  7221530D30027*
Intermediate wheel ref.  7221530D30012
Goal of the technical modifi cation:
Further improve the accuracy of the seconds hand jump in 
relation to the dial markers, including a reduction of the 
wheel engagement play.
Interchangeability
New and old wheel executions must not be mixed; there is a 
serious risk of blocking.
Calibre version 1538C was produced with old and new 
wheel executions.  We therefore suggest to systematically 
using new wheels from the KIT ref. 7221530D9999*.
Version D
Kit Ref. 7221530D9999*
New seconds wheel (yellow) and 
intermediate wheel (grey).
Reduction of the play of the wheel engagement 
to improve seconds hand jump.
New version from date code: 42/07
The policy for local repair is:
We recommend a movement exchange (see Working 
Instruction no. 31). 
In case of local repair, the exchange or replacement of 
spare parts must be made according to the movement 
version (see engraving on main plate).  Example: On a 
movement calibre 1538B, the parts to exchange or repla-
ce are those mentioned under version 1538B. 
Technical modifi cations on version «B»
Calibre 1538A + 1538B 
Application :
When repairing a version A or B, the new components 
must be used systematically.
Goal of the technical modifi cations: 
Improve the accuracy of the seconds hand jump in relation 
to the dial markers.
Version A / B / C
Ref. 722143030012
Ref. 7221538B30027*
 Old seconds wheel (grey) and 
intermediate wheel (yellow)