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Discussion Starter · #1 ·
I have owned three Seiko 6139’s chronographs over the past couple of years, the last two of which, a pair of 6139-6002’s, one blue and one gold dialed, turned into a couple of beauties.

They are now both gone, and I had mentally set that particular element of the Seiko vintage experience to one side, in part because of the grief involved in sourcing all the case parts when restoring these watches but in particular because finding folk to service them is becoming increasingly difficult. Richard Askham serviced my blue dialed 6002 and did a fantastic job, but he has now stopped working on these movements, I think partly because of the difficulty in sourcing parts, but also because they can involve a disproportionate amount of time to get them working properly. Anyway, in spite of apparently having ticked the 6139 box, I found myself bidding on a black dialed 6139-6012 on one of Watchco’s Ebay auctions in June last year and winning it. The dial and handset looked mint, the case a little tatty with plenty of grime in evidence. But more problematically, the movement was not happy, running very slow, and the chrono function was, more worryingly, out of synch with the rest of the watch (although this did not become clear until later). This latter problem is a sign of the common symptom in these watches of a slipping chronograph clutch with the result that the forward momentum of the second hand at each tick, causes the clutch to slip, impelling the hand forward more than it should, with the chrono then appearing to run faster than the watch. I had this same problem on the blue watch above, and Richie fixed it by replacing the chronograph centre wheel. You can see the clutch ring on this cross-section drawing taken from the service document for the 6139A:

But with Richie not accepting any more 6139’s, it looked like I had a paperweight on my hands. I did make inquiries with another recommended watchmaker in Bristol, but their estimate was well into three figures, so that appeared to be that. But then Lew very kindly offered to take a look – all I had to pay was the postage. This I did gratefully, but with the movement now running properly, the out-of-synch chrono problem became evident and so at this point I shelved the project.

And then, a month later (July 2010) I spotted another 6012, this time a gold faced dial, also in a Watchco auction. Worth a shot to see if the movement could be transplanted into the black dialed watch. I won this one too, again for peanuts, and in due course it arrived. But Sod's law struck again, with the movement barely running at all. So, I now had two paperweights. Here they are:

At this point, the two watches assumed a rather forlorn position in my parts drawer, regarding me in an accusing fashion from time to time. But slowly my courage gathered itself up and, with nothing whatsoever to lose, and everything to gain, I thought – how much more difficult can a 6139 be compared to a 6309, 6119 or indeed 6106, all of which I have stripped and rebuilt on numerous occasions? The base calibre of this movement is, after all, a 6106. I decided to attempt a service of the movement fitted to the golden dialed watch because there was the possibility that the chrono centre wheel on this one was ok. I would then fit the black dial and handset assuming all went well. Cosmetically it also looked the cleaner of the two.

I started the adventure, expecting it to be no more than a learning exercise, and to have a movement at the end of the process that might run as a watch, assuming I could reassemble it, but not realistically expecting the chronograph to function correctly. So, we start, having removed the hands, with the top of the movement, auto-winder removed, revealing the pawl lever seat, the pawl lever and the transmission wheel, all part of the automatic winding mechanism:

With these removed we get a better view of the chronograph bridge which supports the hammer click (the mechanism that provides the resistance you experience in pressing the reset button) and which I've unhooked from the nipple on the hammer, and the minute recording jumper:

Next, we remove the chronograph bridge and get a good view of the minute recording wheel (the cog on the left), the intermediate minute recording wheel (next to it on the right) and the centre chronograph wheel (north north east from the intermediate wheel. To the left of that you can see the reset hammer that snaps the second hand and minute recording hand back to their zeroed positions when you push the reset button:

With the coupling lever spring (top above) and hammer spring (left above) and hammer all removed we see the two coupling levers whose job it is to lift the clutch ring off the fourth wheel when the chronograph is stopped (see diagram above). When it restarts (by pressing the upper chrono button) the clutch ring is released and is pushed down onto the fourth wheel by the clutch spring. The slippage I was experiencing with the black dialed watch may have been due either to a weak spring, or perhaps to clutch slippage due to mucky neddy on the clutch surfaces and/or fourth wheel.

Now, with the minute recording and intermediate wheels, plus the levers removed, we have a better view of the chronograph wheel. You can see here the chronograph finger curving round at the bottom of the wheel whose job it is to transmit the instruction to the minute wheel to turn one click, once per revolution of the chronograph centre wheel. For this to work properly the chronograph finger has to be properly aligned with the teeth on the intermediate minute wheel.

Here's the chrono wheel out of the watch:

With the barrel, chrono wheel, balance and centre wheel bridge removed we have just the pallet c o c k, fork and staff and escape wheel to go

Here are all the bits and pieces

ready for this:

which contains extremely noxious ammoniated watchmaker's cleaning solution.

While that's doing its thing, we can turn our attention to the case

which needs a jolly good clean, as you can see here:

After the toothbrush, toothpaste and if memory recalls a go in the ultrasonic bath it is looking a bit better

With internal bezel, bezel ring, crystal gasket back in place

the case is ready to receive its lovely new crystal, courtesy of Sternkreuz via Cousins

A nice view of the internal dome here:

Onto the case, looking good

on with the external bezel

and we hit a snag. I cannot get the bezel to seat properly, no matter how much force I exert with the crystal press. In the end I realise the problem lies with the crystal. It is too deep and the bevel is fouling on the inner diameter of the bezel. I fitted one of these to the blue watch pictured at the start of this epic without any such problems but had heard from others that sometimes they don't fit. The solution required simply sanding down the bottom edge of the crystal until it fouled no more.

With the movement bits clean and shiney, the movement reassembly and oiling proved reasonably straightforward, with the exception of one issue that I'll get to in a moment.

With the hands test fitted, the problem that revealed itself was that neither second nor minute register hands were resetting properly. Perusal of the service sheet for the 6139A does not offer much comfort to an amateur such as myself, suggesting polishing the setting surfaces of the hammer to get it to contact properly with the minute and second hearts, located respectively on the minute register wheel and chronograph centre wheel. However, this is not a 6139A but a 6139B, and those clever chaps at Seiko had installed an eccentric screw to allow you to change the balance between the two registers - something that was pointed out to me by the ever-helpful Richard Askham. You can see it in the photo above just below the pillar wheel. I suspect that at some point in the disassembly process, I had tampered with said screw upsetting the balance between the two registers. A 180 degree turn was all that was required to effect a cure. You will note also in this photo that the minute register wheel has changed colour as has the hammer. This is because in attempting to find a diagnosis for the problem I substituted these two components from the other watch.

In this shot, I am depressing the reset button which impels the hammer to impact upon the two hearts, resetting the two registers.

A close-up of the chronograph bridge shows the chrono finger and minute recording jumper correctly seated in relation to the teeth on the intermediate wheel and minute wheel respectively.

You can get an idea of what is involved in setting this up properly from the following

I hasten to add that it all simply worked when I reassembled the movement - no adjustment required on my part, which is just as well.

At this point, we are ready to pop the hands back on, having swapped the dials between the two movements. First, on with the hour hand

then the minute hand

and then the minute register hand


You will see, I was using the other, uncleaned case to hold the movement, hence all the grime. At this point another hurdle. The red second hand originally fitted to the black dialed watch is effectively dedicated to the chronograph wheel fitted to that movement, but we have swapped movements. Fitting the hand to the replacement movement resulted in it being misaligned when zeroed. This happens because the shaft on which the hand is seated on the chrono wheel, is profiled thus

to prevent slippage when zeroing. And there is no guarantee that the shaft will be oriented in the same way on every movement. So a new chrono centre wheel requires either a new hand or for the old impression to be filed out from the inside of the tube with a cutting broach - something Richard A. told me often still leaves the hand insufficiently well secured. Unable to source a replacement hand of the correct colour, I resolved to paint the yellow hand originally fitted to the gold faced watch

As it had originally been mated with the chrono wheel now fitted to the black faced watch, it should align correctly when zeroed. After much experimentation, the correct colour and consistency of paint was obtained by mixing some red railway modellers emulsion,

with some GlasArt blue transparent paint, to get the correct brownish tinge to the red colour, all thinned out using lighter fluid. The resulting finish is excellent and the colour match almost spot on. The hand re-seated without further trouble (remembering to depress the reset button when fitting). Next up, remove the gaskets from the crown and pushers

fit new, greased gaskets (fiddly as hell)

and we are on the home straight.

I've been wearing the watch since last Thursday night when I finally finished (after 10 months work, on and off!) and so far it has gained about 12 seconds since then (i.e. a net +3 seconds per day).

and a wrist shot from last Friday

While I rather like it on the NATO, the watch did come with its original bracelet. A soaking in the ultrasonic bath in some watch cleaning solution, followed by a swap of one of the links from one side of the bracelet to the other, and we have something that starts to approximate what it might have looked like in 1975, when it was bought by its first owner:

The version of the watch I have is fitted with the same bracelet as the one on the left below, shown I think in a catalogue (original scan by Isthmus I believe) from 1974

The bracelet is lovely, elegant and very comfortable. It's staying on as long as it continues to appear to want to stay in one piece!


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41 Posts
Oh yeah! Love what you did and love the watch! Excellent post!

There should be a finding and acquiring guide for these on the
forum. Wonderful watches, but here in Sweden most of them
are wrecks and in my experience most watchmakers think
Seikos are crap. So, for me, hard to find but potential grails.

Again, love it! / Christian

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5,978 Posts
^-^ Martin,

It was a comment I made about some wanker that spammed the site a couple of weeks ago, that immediately preceeded my entry. It has been removed by the Mod's and so my comment make no sense now. It is not a comment about you; you are great :) good work on the 6139,s.


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286 Posts
Discussion Starter · #11 ·
Ah, thanks for that Mike. I've been away for a couple of weeks and so missed the context completely.
All the best

pollyc said:
Hi Martin,
I[size=1em]t was a comment I made about some wanker that spammed the site a couple of weeks ago, that immediately preceeded my entry. It has been removed by the Mod's and so my comment make no sense now. It is not a comment about you; you are great :) good work on the 6139,s.

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6,987 Posts
that watch is incredible...amazing job

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21 Posts
Great post! Sorry for the revival. I just followed your steps and got my hands back on and everything was OK!

I have had this movement for a while and I know that it always seems to reset the seconds sweep hand at 2 seconds. I saw how you adjusted the eccentric screw near the column pillar wheel and brought it back to zero.

I did this and huzzah it came back to zero, but then it just randomly whent out of whack and, everytime you press flyback (even if the chrono isnt running), both the seconds sweep and the minute counter jump around to different positions and stop there.

Any ideas? Any help would be much appreciated.
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