Calibre 633 was a member of the Jaeger-LeCoultre Mechaquartz family. It was the most complicated movement in the family, with 27 jewels and an alarm function.
There are two motors in the calibre
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.
Calibre 633 differed from Calibre 630 and 631 in that it included an alarm function.
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.
Calibre 633 was used in chronograph watches in the 1980's and 1990's, though not as widely as Calibre 631