The Seiko 6139 and 6138 series - the ever-popular 1974 Seiko 6138-8020 "panda" here counts itself among the latter - were the first fully integrated automatic chronograph in the world featuring column wheel and vertical coupling mechanism. A feature of these sporty 6138-8020’s were their unique "panda" dials, hence the moniker.
With the 6138 movement, Seiko - as usual - set the standard followed by the Swiss watch industry 20 years later. The same movement configuration was adopted by Rolex when it made its own in-house movement for the Daytona in 2000, 30 years after Seiko released its 6139 and 6138 calibres. Oddly, the 6138 was the successor of the 6139 automatic chronograph movement, and produced in parallel with it until 1979.
The 6138 was technically at least equal to its Swiss counterparts, as it featured a fully integrated chronograph vice stacked modules. There were two versions of the 6138, with the first, the 6138A, introduced in 1970 with 21 jewels. The 6138B – like the one for sale here – was introduced subsequent, and featured 23 jewels. Both had a column wheel that regulated chrono functions, and a vertical clutch mechanism for engagement.
The 6138A/B was a two register chronograph, counting up to 30 minutes on one subdial and another 12 hours on the second dial. All 6138 movements feature a quick-set day/date indicator and can be handwound (unlike the 6139 model), relatively unique for Seiko chronographs of this era.
This 6138 Panda comes with a leather strap, nylon NATO strap, Pelican travel case, and springbar tool.
1974 Seiko 6138-8020 "Panda" Automatic Chronograph
DIAL: Light gray/silver "linen" Seiko-signed dial, with matching hour, minute, and chronograph hands. Day and date function - with Spanish/English numeral day variants - at the 3 o'clock position works as designed.
CASE: Stainless-steel case measures 40mm (w/o crown, 41.5mm with) x 46mm; matching caseback. Case lines are sharp, with no evidence of machine polish
CRYSTAL: Flawless domed Seiko 6138-correct acrylic crystal, no scratches or imperfections.
BAND: This Panda comes with a black leather strap; it also comes with a gray nylon NATO strap - both feature stainless-steel hardware.
MOVEMENT: 6128B Seiko 21-jewel automatic movement, manufactured in December 1974, which beats at 21,600 beats per hour.
CROWN: Unsigned stainless-steel crown.