Seiko 6139-7012
The 6139-7012 is a Japanese domestic market Speed-Timer from the early 1970s, built around the caliber 6139 automatic chronograph with its single 30-minute register, day and date at three and an inner tachymeter ring. What sets it apart from other 6139 cases is a black dial with Arabic hour numerals, which is why collectors call it the Military. The name is partly earned. Some examples were issued to the Japan Air Self-Defense Force, and those carry the JASDF name, a cherry blossom and wings insignia and an individual number on the outside of the caseback, with the Seiko serial moved to the inside. The same reference was also sold to civilians, so the caseback, not the dial, is what identifies an issued watch. Chronograph hands are normally yellow; the example shown here wears orange ones.
| Caliber | 6139 |
|---|---|
| Years | 1971 to present |
| Line | Seiko 5 Sports |
| Function | Chronograph |
| Sub-line | Speed-Timer |
How can you tell a JASDF-issued 6139-7012 from a civilian one?
By the caseback, not the dial. Issued watches have the Japan Air Self-Defense Force name, the cherry blossom and wings insignia and an individual number engraved on the outside of the caseback, with the Seiko reference and serial stamped inside. The dial and case are the same as the civilian watch, so a plain caseback means a civilian example, and a crisp engraving on a worn case is worth questioning.
Why is the 6139-7012 called the Military?
Because of its dial. It is the Japan-market 6139 case with a black dial and Arabic hour numerals, a look closer to a pilot's instrument than the baton dials on most Speed-Timers. Some were issued to Japanese Self-Defense Force pilots, which reinforced the name, but most examples were sold to civilians.
What movement does the 6139-7012 use?
The caliber 6139, one of the first automatic chronograph movements, with a column wheel, a vertical clutch, a single 30-minute register and day-date. Examples are found with 17 or 21 jewels, and the day can be shown in Japanese or English. It does not hand wind, so it relies on wrist movement to stay running.
