Zenith 684

	Brand:	Zenith
	Family:	Zenith Elite
	Height:
	Jewels:	26
	Reserve:	50 hours
	Frequency:	28,800 A/h
	Winding:	Automatic, Bi-Directional Automatic Winding, Central Rotor Automatic Winding
	Diameter:	25.60 mm (11.5 ligne)
	Complications:	Date, Hacking Seconds, Instant Date Change, Quick Date Correction
	Hands:	Central Hour Hand, Central Minute Hand, Date Window at 6:00, Small Seconds Hand at 9:00

Distinguishing Technical Characteristics
Central-Rotor Automatic Clockwise Balance Cock Balance at 1:30 Barrel at 7:30 Central Rotor
Production:  –
1910s	1920s	1930s	1940s	1950s	1960s	1970s	1980s	1990s	2000s	2010s	2020s

Cal. 684 is a thin automatic movement with date from Zenith. Closely related to other Zenith Elite movements, Cal. 684 has a simple design with small seconds at 9:00 and date at 6:00. It is thus identical in specification to Cal. 680, with the only difference being the move of the date window from 3:00 to 6:00.

Cal. 684 appears in the 2000s and was used in Zenith Port Royal watches in a square case. It appears to have been short-lived and is no longer listed in the catalog as of 2011.

Technical Aspects of the Zenith Elite Movement

The basic Elite movement measures 11.5 ligne (25.60 mm) diameter and most models are under 4 mm thick, despite a central automatic winding rotor and date complication. A few models used a larger main plate to move the date window outward or to support complications like a running 24 hour ring. The thinnest Elite movement is the hand-winding Cal. 650 at 2.83 mm and the thickest and most complicated is the large Cal. 687 at 6.20 mm.

Unusually, many Elite movements (apart from the 660 and 670 lines) feature small seconds at 9:00, a distinctive feature that differentiates the watches that use it. Some, however, feature central seconds, an adjustable 24 hour hand, a power reserve indicator, and other complications.

All Elite movements use an annular Glucydur balance wheel with a self-compensating balance spring and fine micrometer screw for adjustment. The automatic winding rotor is mounted on ball bearings like the ETA 2892 and originally included a tungsten carbide element for higher winding power. Most Elite movements boast 50 to 55 hours power reserve and all operate at 28,800 A/h.

Zenith Elite 680 and 690: Small Seconds

Cal. 680 was one of the original Elite movements introduced in 1994 and remains in production today. Most of its descendants feature small seconds at 9:00, though Cal. 690 lacks running seconds and the rare Cal. 689 relocates the subdial to 6:00.