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JLC 631

Calibre 631 was a quartz watch movement with a mechanical chronograph developed by Jaeger-LeCoultre and also used by IWC.

Introduced in 1987, Calibre 631 was the second member in the Jaeger-LeCoultre Mechaquartz family after Calibre 630. It was a complicated movement, with 25 jewels and 233 components.

There are two motors in the calibre

  • One powers the main timekeeping hands at a frequency of 1 Hz
  • A second powers the mechanical chronograph at 4 Hz

Since the chronograph is mechanical, it has the same feel as a conventional chronograph movement, including mechanical zero reset. Yet the Mechaquartz was much more compact than a conventional automatic chronograph movement.

Note There is conflicting information on the quartz frequency, with some sources claiming dual 1 KHz and 4 KHz crystals and others claiming 32 KHz.





  • Hour, minute hands
  • Small seconds at 6 00
  • Chronograph with 30 minute and 12 hour subdials at 9 00 and 3 00, respectively


  • H 3.8 mm
  • D 23.3 mm
  • 25 jewels
  • 233 components
  • Frequency 32 KHz

Production period:

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jlc_631.txt · Last modified: 11.10.2021 21:09 (external edit)

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