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The Encyclopedia of Horology

Movement record · Switzerland

Valjoux (ETA) 7750

Verified

A cam-and-lever chronograph module integrated with an automatic base, designed for efficient volume production rather than for the finish of a column-wheel chronograph; briefly discontinued in the 1970s crisis and revived in the 1980s to become an industry-standard workhorse.

Technical specifications

Diameter
30 mm (13¼ lignes)
Height
Approx. 7.9 mm
Jewels
25
Frequency
28,800 vph (4 Hz)
Power reserve
Approx. 42–46 hours
Winding
Self-winding
Setting
Pull-out crown
Escapement
Swiss lever
Balance
Glucydur-type balance, Nivarox hairspring
Complications
Chronograph (cam-actuated), Day-date

Identification features

  • Cam-actuated chronograph mechanism visible on the movement side under the automatic rotor
  • Distinctive bridge layout documented in ETA technical sheets

Known variants

  • 7750 base
  • Modified/decorated versions produced under licence or after patent expiry by other makers

Servicing notes

Well documented and widely serviced; parts and technical sheets are readily available.

General guidance only. Antique movements should be serviced by a qualified watchmaker.

Historical significance

Probably the most widely produced mechanical chronograph movement in history and a benchmark of accessible chronograph engineering.

Diagram

top plate or bridgespillar platebalance and cockwheel train between the plates
Schematic: plate and bridge layout. An outline schematic drawn to show the arrangement of the parts discussed here. It is not a dimensioned working drawing and does not depict a particular maker's calibre.

Sources & references

  1. ETA technical documentation
  2. Trade and industry histories of the 1970s Swiss crisis

Where sources disagree, the disagreement is stated rather than resolved silently.