You need look no further for evidence that the 1960’s were truly a golden era for Seiko than the wonderful selection of watches produced during that decade under the Seikomatic branding. The first Seikomatic appeared in 1960, simple in form and function but rather lovely and providing the foundation for a range of elegant, stylish watches spanning the elevated consumer to more luxurious end of the market, with features including waterproof cases, calendar complications and of course an automatic movement featuring the magic lever mechanism.
That first Seikomatic was fitted with the automatic 603 calibre (subsequently named the 6201), a 27.6mm diameter movement running at 18000 bph and coming in 17, 20 or 30 jewel variants (we encountered the 20 jewel version a couple of posts back here in that splendid Seikomatic SilverWave). The date complication first appeared in the Seikomatic Selfdater of 1962 fitted with the 24 jewel 394, the precursor to the 6205. That in turn spawned the luxurious 39 jewel 395 Self Dater 50 Proof of 1963. From 1963 through 1967, Seiko released a number of Seikomatic Selfdaters and Weekdaters, the latter of which used the 400/6206 movement and which spawned the first automatic chronometer Grand Seikos. All of these watches used variants of the 62 series of movements which traced their lineage back to that 603 of 1960. A second tier of Seikomatic joined the 62 series watches from about 1964/5 fitted with the 83 series movement.
This post enters the fray in August 1964 with a slightly weathered example of a Seikomatic Weekdater 6206-8990. Earlier incarnations of this particular model appeared in mid-1963, fitted with the 400 movement. Mine, whilst numbered according to the newer model naming conventions, is an early enough example to feature the gorgeous Seikomatic script on the dial. Here it is as received:
Pretty presentable on the whole, the usual scuffed and slightly crazed acrylic crystal and a chapter ring curiously missing most of the minute markers but a handsome thing nonetheless.
The movement is an absolute peach, looking resplendent in all its golden glory:
and with a gentle rock, slips lazily into its rather leisurely rhythm as the balance wheel swings back and forth at its native rate of 5 beats per second:
A quick check on the timer reveals it’s running slow but with an excellent amplitude of about 250 degrees. Removing the movement, bezel and crystal and we see some clear signs of exterior corrosion to the case, but hopefully just flakey suface oxidation that should clean off.
The dial is in generally excellent condition though, barring the faintest hint of spots of discolouration in one or two places around the extreme edge whilst the hands are decent too, if a little grubby:
Here’s a closer look at that lovely printed dial script:
Off with the dial and hands and that beefy looking case ring, used to secure the movement to the mid-case, and we can start the dismantling process, calendar side first
You may have noticed the two-tier arrangement of date and day wheels, which we’ll get to again later, and the dial ring, secured to the mainplate by three screws, which provides a secure base for the periphery of the dial to sit upon. You can also see in the photo top left that the date dial guard and date jumper guards are fitted with a jewel each, presumably to aid the easy passage of the day wheel as it performs its duty. The day jumper spring incidentally sits in a furrow to the rear of the date jumper guard
Turning over we can attack the balance side:
Not much to cause any concerns here other than the ubiquitous leakage of moly grease from the barrel arbor. The only wear or damage I could find anywhere was the secondary jewel fitted to the centre wheel bridge, which had cracked in a number of places:
Fortunately, I have a spare 6206A which I have farmed for parts in the past and this gives up an undamaged replacement.
With the movement completely dismantled and cleaned we can appraise the component parts, with Diashocks, cap jewels and screws off stage left somewhere.
Reassembly starts with the refitting of the mainspring to the cleaned and lubricated barrel
followed by the Diafix settings on the main plate and train wheel bridge:
The Diafix and jeweled bearings on the main plate and train wheel bridge account for 12 of the 26 jewels. Next up, the keyless works come together, then the centre wheel and centre wheel bridge (which, together with replacement secondary jewel fitting accounts for a further two jewels) before returning to the calendar side to fit the minute wheel and cannon pinion:
Next, we fit the barrel and train wheels followed by the train wheel bridge:
In with the pallet fork and pallet bridge (3 jewels)
balance, with Diashock settings refitted both sides, a few clicks of power wound into the mainspring and off she goes:
With the four jewels in the Diashock settings, the impulse jewel on the balance wheel, the jewel count stands at 22. A quick check that all looks healthy on the timer and we can refit the calendar parts (bringing the jewel count to 24 with those two jewels in the date dial guard and date jumper guards) and take a look at how the different levels at which the day and dates wheels sit are accommodated by the dial. You can see from this shot of the reassembled calendar how the day wheel sits considerably proud of the date wheel:
The fact the it’s not flush means that the dial needs a recess machined in its rear to make room:
I’m not sure if this is intentional or the result of the day complication being retro-engineered to a movement not originally designed to accommodate such a feature but it does add a nice three-dimensionality to the dial landscape.
Although the original hands are perfectly presentable, a few pounds splashed out on a new set adds a nice little lift to the appearance of the watch face:
With the innards sorted, we can give the case a clean:
refit a replacement chapter ring, complete with all its ticks, and the crystal, pausing to note that the it sits on the outside of the case lip, rather than on the inside
with the waterproofing (such as it is) then assured by the bezel squeezing the acrylic against the lip from the outside
All that remains then is to fit the movement to the mid case
fit fresh gaskets to case back and crown, and then add the auto-winding mechanism (which with its two jewels brings the jewel tally to 26)
and we are finished. Resisting the temptation to lower the tone with a NATO, its on with a black leather strap to complete the picture.
David Bidwell said:
Beautiful watch and what an attractive movement. And you make it sound so easy like the celebrity chefs on TV. I do wonder what tool you use to get that bezel off without marring the finish. I have newer Seiko 5 and haven’t been able to figure out how to get it off.
Many thanks for that. This type of bezel can generally be levered off using a simple Seiko style watch case opener. This operation is helped by the shallow wedge machined into the bezel edge at one point on its circumference to make it easier to inert a case knife but its accessibility requires that a previous watchmaker has remembered to refit the bezel with the wedge conveniently positioned! If that does not work, then you can try a scalpel blade and then gently work it around to create enough space to insert a case back knife.
Bought this watch at antiques fair today and after web search found your blog. Thanks for a fascinating insight into my purchase
Michael Fleischmann said:
Hello, i just read this wonderfull blog about youre watche.
I have exact the same watch but in gold. It is a 606-8980. Saddly it is not running anymore but apears to be in very good condition. Are you doing service for this watches or can you direct me in the right direction.
Thanks in forward for an answer. BR
These are lovely watches, I agree. I am afraid that I don’t work on watches other than my own but if you are in the UK or Europe, then I would happily recommend Richard Askham who does excellent work. If you do a search for thewatchspotblog you should find him. If you are in the USA, then you might try Spencer Klein. I have no direct experience of his work but he seems highly regarded. Good luck!
Richard Rix said:
What a wonderful article. I’ve just bought one of the above watches. It keeps perfect time, but so far doesn’t store enough energy to survive the 8hs per night when I’m sleeping. I am an absolute amateur and my question is can I hand wind the watch to give the additional power to last the night. It’s falling short by about 3hrs at the moment.
Richard, thank you. The only way to manually wind in power with the case back still in place is to swirl the watch about to get the rotor doing its thing. However, this would be a major chore to have to do each day and defeats the purpose of the automatic winding function and it may also not necessarily achieve what you want. If the watch is not holding more than 8 hours of power, then that suggests to me either that the autowinding mechanism is not functioning properly or that the bridle on the mainspring is slipping badly. If the former, then the likely reasons are either badly worn tips on the pawl lever which impedes their ability to grip the transmission wheel or, perhaps, a worn out centre bearing or loose screw causing the rotor to drag. The only way to tell for sure is to get the back off (relatively easy with a Seiko style watch case opener) but then you need also to be able to get it back on again afterwards. Sometimes, that can be accomplised with fingers only but more likely you’d need a crystal press. Problems with the autowinding mechanism ought to be an easy fix. Problems with the mainspring would require the movement to be stripped down further and you may then simply decide to spring for a full service.
Best of luck!
Hi Martin, I had a quick question for you (or any other vintage seiko experts). I am attempting to replace a broken crystal on a 1962 seikomatic (non date, 20 jewel 603? movement). The crystal is very broken and as a result can not press it out on my crystal press. All that is left of the old crystal is a very thin ring in the case and between the bezel ring. In the 24th picture above you show the case, caseback, and bezel ring. Is this bezel ring glued on? If so, is a heat gun recommended? And is there a common glue that is used during reassembly?
Thank you for any help, I am at a stand still!
Hi Martin, please disregard my last comment. I went back and re-read and saw your response to David’s question so I braved it with a razor knife and eventually got my case knife in there! Now to order a replacement acrylic, is a crystal lift tool required to fit this?
Thanks again, this site is an immense help
Glad you got it sorted Branden.
John Beck said:
Just a terrific site.
The level of craftsmanship, taste and eloquence is unparalleled. You are very talented.
Do have a question for you. Am considering creating myself to a 6205 but am wondering what the true level of water resistance is. I know they are labelled as water proof but for the 1960s does this just indicate safe showering? Or is a swim in order as well?
Thank you so much
Many thanks John. I am very pleased to hear that you enjoy the site. As to your question, in common with most of the Seikomatic models of this period, the 6206-8040 is equipped with rubber caseback and crown gaskets and an acrylic, tension ring crystal. In addition, the 8040 has a screw-down case back rather than press fit. With fresh gaskets, a new crystal and a case free from corrosive pitting, there is no reason to suppose it should not be good for a 50m water resistance rating. In theory, that should mean that it is more than up to the task of being worn when swimming, but as with any vintage watch, you should approach such activities with caution unless the watch has passed a proper pressure test.
John Beck said:
And my apologies, I did mean a 6206…specifically 8040
Alexandros Lekkas said:
I have the same, but small details are different ! I wish i could send you some photos
You are welcome to send photos to the email address given under the Contact tab.
Diane Morris said:
How do you set the day? 6206
No quickset day. You advance the hands through midnight to about 2am and the reverse back through midnight to maybe 9pm and then forward again through midnight. A sort of semi-quickset.
Tony Goodman said:
Hi. Thanks very interesting article. I have the same watch a June 64. I brought it from the original owners grandson. It actually came with the original box and bracelet, although I spent a few years finding links for it. The guy is likely in the Guinness book of records for the words smallest wrists. I thought mine were girly but his were tiny. Anyway great watches. I just serviced mine and it is keeping superb time and power. Thanks again vastly underrated these vintage Seiko watches. Be lucky!
Agreed. Classics of that time. Enjoy your watch!
Thanks for a fascinating article. I also recently acquired what I am told is a June 1964 Seikomatic as I wanted a watch from my birth year. I had it serviced and changed the non-original strap on it to one with a matching gold buckle. It’s in amazing condition and the date and day complication is lovely. Even though its vintage, its size wears well on my 8″ wrist. I was also told by my watch jeweller that you cannot wind it manually. I was surprised. Mine doesn’t stop overnight but it does lose 5 minutes overnight whereas when wearing it during the daytime it keeps good time. My jeweller is having another look at it but I sent him your comments above in answer to the watch stopping overnight. I suspect my problem is similar. I’d post some photos but don’t think you can do this on here.
I think you can post [IMG] links to photos hosted elsewhere but you can’t upload photos to this site. I’m glad you found the article helpful. Best of luck getting to the bottom of your issue.
Thanks and noted.
John Millar said:
Great walk through, and lovely watch. I’ve a similar 6619-8010, wondering how you refit the crystal and bezel? Thought I could do it by hand, but it’s not working out
On my watch, the crystal fits by hand but the outer bezel then needs a crystal press. This crystal sits outside a circular lip around the dial aperture and the seal is created by the outer steel bezel. On other models, the crystal features a tension ring and those crystals need a crystal press to seat.
What Crystal did you replace it with?
I see some NOS but they are getting expensive. Was wondering if you had SternKreuz reference.
The 6206 8980/8990 both fit 338W01AN hence my question
David Courtney said:
Just done the same with a 400 movement (33 Jewel 1963 Weekdater). I was wondering if you knew the lift angle for this movement.
Thanks and nice work by the way. A man after my own heart 🙂
Hi David, I’m afraid I don’t know the lift angle for the 62 series. I’ve not yet found any published information and doubt that there is any out there. I am pleased to hear that you find the blog useful.
Hell, what size crown gasket did you use to replace the old one? I used a 1,7 X 0.7 X 0.5 generic replacement, but it seems bit narrow. Thanks!
Hello, what size crown gasket did you use to replace the old one? I used a 1,7 X 0.7 X 0.5 generic replacement, but it seems bit narrow. Thanks!
I am away at the moment but will check my records when I get back.
Hi I inherited a seiko weekdater 6206-8080 from my grandfather. The glass is cracked and I wonder where I can buy a new one? On the internet I mean, I am a French reader.
By the way, great article!
The part number of the crystal for your Weekdater is 315T03AN. It is not available from Cousins, the UK watch material house but there seem to be some eBay sellers in the USA (a bit pricey factoring in the postage) and one or two aftermarket options – https://www.tiptopcrystals.com/index.php?main_page=product_info&products_id=7634 for example. Good luck with your search! All the best Martin