The Seiko 6139 and 6138 series - the serviced 1976 Seiko 6138-0030 "champagne kakume" here counts itself among the latter - were the first fully integrated automatic chronograph in the world featuring column wheel and vertical coupling mechanism.
A unique feature of these sporty 6138-0030’s were square hour and minute subdials, hence its nickname “kakume,” Japanese for “square eyes.” Unusual for the time, this 6138 is rather hefty in size, measuring in at 43mm in width.
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 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 is 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 Kakume comes with a leather strap, nylon NATO strap, Pelican travel case, and springbar tool.
1976 Seiko 6138-0030 "Champagne Kakume" Automatic Chronograph
DIAL: SpeedTimer Suwa-signed dial, with NOS hour and minute hands. Day - with Spanish/English day variants - and date function at the 3 o'clock position work as designed.
CASE: Hefty stainless-steel case measures 43mm (w/o crown, 44.5mm with) x 45.5mm stainless-steel cushion case, which has received a light polish at some point in its nearly 50 year life. Matching caseback. While the orange chronograph hands appear to be quality aftermarket, the minute and hour hands are a correct Seiko new-old stock set
CRYSTAL: Hardlex crystal, scratch-free.
BAND: This Kakume comes with a brown leather strap, as well as a black nylon NATO strap, with stainless steel hardware – a comfortable and stylish strap that compliments the colors on this vintage Seiko 6138 Kakume.
MOVEMENT: 6128B Seiko 23-jewel automatic movement, manufactured in April 1976, which beats at 21,600 beats per hour. We have performed a full service on this watch.
CROWN: Unsigned stainless steel crown.