Heraļon MechaQuartz Chronograph, Cal. 631
Notes about opening the Back
Battery Renata 397 is removed in this picture, also the gasket ring is not shown in this picture. The Jaeger-LeCoultre watches are really easy to open, the big case back screws make it a pleasure to have a look inside the watch. And I think it is a good decision to make quartz watches with screwed backs, especially if those screwed backs come in this quality. Because quartz watches need to be opened more frequently then automatic watches. The screws are big and strong. Even this watch had not been opened for more then 10 years, the screws were not oxidized and it was easy to open them with a watchmaker's screwdriver. Just make sure you use a screwdriver that has the same width as the screw slot. Otherwise you will leave marks on the case back screws.
Please click here to see an example of the same Caliber 631 used by IWC
Please click here to seen example of the Caliber 633 used by IWC, basically the same movement but with an alarm function