Knowledge Center

Professional Authentication Platform

Log InRegister

Seiko 6138B

Probable

The two-register companion to the 6139. Both are integrated chronographs using a column wheel and a vertical clutch — an architecture that would not become common in Swiss chronographs for another thirty years.

Specifications

Movement manufacturer
Seiko
Production
1970–1979
Frequency
21,600 vph (3 Hz)
Winding
automatic
Complications
Chronograph · 12-hour totaliser · Day-date

Architecture

Automatic chronograph with a column wheel and a vertical clutch, adding a 12-hour totaliser to the 6139's single 30-minute counter. Integrated rather than modular.

Authentication notes

  • MovementHigh confidence

    Count the subdials before accepting the reference

    A 6139 drives one 30-minute totaliser; a 6138 drives a 30-minute and a 12-hour. A dial with two subdials over a 6139 movement, or one subdial over a 6138, is a mismatch visible without a loupe — and it is the most common consequence of the two families' parts being interchanged during restoration.

Service practice

The chronograph work is serviceable but parts are scarce, and a seized vertical clutch is the common failure. A 6138 whose chronograph does not reset cleanly needs the movement assessed on its own terms before the watch is valued.

Related calibers

  • Related caliber

    Seiko 6139

    Shares the architecture; the 6139 has no hour totaliser.

References using this caliber

Provenance of this record

Sources & Evidence

Primary sourceTechnical documentation

Seiko caliber technical guides and parts catalogues

Seiko Watch Corporation / Seiko Instruments

Accessed
2026-08-18

Cited for

This referenceHigh confidence
Secondary sourceSpecialist publication

Fratello Watches — Seiko 6139 and the Pogue

Fratello Watches

Accessed
2026-08-18

Cited for

This referenceProbable
View source ↗

Last verified: Not yet reviewed