Jaeger-LeCoultre Caliber 823 – Technical Overview from Document 1139_JLC

The Jaeger-LeCoultre Caliber 823 is a manual-winding mechanical alarm movement with date display, developed in the early 1970s as a refined version of earlier Memovox calibers. Document 1139_JLC offers a full technical breakdown of the movement’s core components, emphasizing its dual-barrel construction, mechanical alarm function, and added calendar complication. This movement combines Jaeger-LeCoultre's hallmark mechanical innovation with enhanced user convenience.

Technical Specifications

• Type: Manual-winding

• Functions: Hours, minutes, central seconds, alarm, date

• Jewels: 17

• Frequency: 21,600 vibrations per hour (3 Hz)

• Power Reserve:

  • Timekeeping barrel: ~45 hours

  • Alarm barrel: ~18–20 hours

• Diameter: ~28.0 mm

• Height: ~6.2 mm (due to date mechanism)

This caliber is a successor to Caliber 819, with the primary difference being the addition of a date display, making it more functional for daily use while retaining the core Memovox architecture.

Key Features from Document 1139_JLC

1. Dual-Barrel Layout

• Two separate mainspring barrels:

  • One for the timekeeping gear train (wound by one crown)

  • One for the alarm function (wound by the second crown)

• Each barrel has its own click, ratchet, and bridge system for efficient manual winding

2. Alarm System

• Alarm disc under the dial, adjusted via the second crown

• Trigger lever and release cam system tied to the hour wheel

• Hammer mechanism that strikes a pin or tone spring against the case to generate the alarm sound

• On/Off alarm switch incorporated into the crown function or an additional control element

3. Date Mechanism

• Semi-instantaneous date change, usually around midnight

• Date wheel mounted under the dial, driven by a finger mounted on the hour wheel

• Date is typically set by advancing the hands past midnight, as quick-set was not standard at the time

Servicing Notes from 1139_JLC

• Balance and escapement: Target amplitude is ~270°, and beat error should be below 0.7 ms

• Hammer assembly must be aligned correctly for effective chime without contact issues

• Avoid lubricating the alarm hammer pivot, as it dampens the sound

• The calendar mechanism should be lubricated only at friction points—excess oil causes drag or sluggish date changes

• Always verify that the alarm and date functions operate independently, with no interference in the gear train

Application in Watches

Caliber 823 was used in:

• Manual-wind Memovox models with date

• Models featuring dual crowns, one for setting time and winding the movement, and one for alarm function and setting

• Mid-sized dress watches in steel or gold, with inner rotating alarm discs and applied date windows (typically at 3 o’clock)

These timepieces offered a rare combination of elegance, functionality, and mechanical ingenuity.

Conclusion

The Jaeger-LeCoultre Caliber 823, as documented in 1139_JLC, is a well-balanced manual movement that merges the classical charm of a hand-wound Memovox with the practicality of a date display. Designed with two independently powered systems, it ensures precise timekeeping alongside a reliable and sonorous mechanical alarm. For vintage collectors and watchmakers, the 823 remains an elegant and technically rewarding movement to work on and preserve.