Seiko Chronograph Pepsi – Cal. 6139A

Posted By on Mar 15, 2016 | 0 comments

Seiko Chronograph – Pepsi – Cal. 6139A


a couple weeks back, Jean dropped off his Seiko chronograph that he received from his father. The watch was in pretty bad shape. The chronograph was stuck in limbo, the date and day wheels were jammed, the crystal was very badly scratched and the movement wasn’t working.

Just a couple shots before I get started.

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With the case back off.


While dismantling these Seiko’s, one must be mindful that the two pushers are held in place with the movement ring. If the pusher springs still have any life in them, and if you accidentally remove the movement ring without holding the pushers in place, they can ping across the room.

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With that done, it’s time to remove the dial, date and day wheels. A little nice trick, when you need to remove the day wheel, use a number 80 screwdriver and gently pry the retaining ring.

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Next, I turn the movement over, put it in a movement holder and start disassembling the movement. I first start by removing the oscillating weight followed by the automatic bridge and finally the Pawl lever and transmission wheel.

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Next, I remove the chronograph bridge revealing the chronograph section of the watch as well as the balance. Followed by the Hammer spring and operating lever spring, being extra careful, as these guys could ping across a room in no time and finding them is no easy task. After the springs, I remove the hammer. And lastly, the train bridge.

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Next, I remove the barrel and third wheel and I then flip the movement over to the dial side.


On the dial side of the movement, I remove the calendar work followed by the keyless works.

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Yup, you most certainly are getting a new mainspring. By the way, this particular movement is very way long discontinued. So, good luck finding an original mainspring. If you know someone who has some, please let me know, otherwise, get a couple for yourself. When I called my supplier asking for one, they suggested that the ETA 2892A2 mainspring is a good substitute.


Next up, the cleaning machine.


The new mainspring gets installed, but not before coating the barrel wall with some breaking grease.


Next, I install the center wheel and pinion, barrel and escape wheel.


Slowly but surely, the watch starts coming alive.


With the train bridge installed and crown wheel next.


I start putting the chronograph mechanism together and greasing and testing as I go along.


Then, time to turn the movement over and start assembling the keyless works.

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And again, turning the movement over, it’s time to finish assembling the chronograph and closing it up with the chronograph bridge.

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Again, turning the movement over, I finish up with the calendar works.

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One more time now, turning the movement over and reinstalling the rotor. Much cleaner looking, eh!


And, time to case it up.


Oh, these pictures should have been inserted earlier, but, here’s the watch on the timegrapher. Seiko’s are notorious for their low amplitude. However, I’m quite happy indeed with the results. Job well done πŸ™‚


Almost done, time to put the hands on.

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And, just a few show off pictures πŸ™‚

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Before and after πŸ™‚

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Once again, thank you for taking the time to read through my boring post with great pictures. Till next time,


Chris Marcellin

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