The Watch Site banner

21 - 33 of 33 Posts

·
Registered
Joined
·
2,201 Posts
Re: Does anyone know the definitive answer to the "X".."J" Japan marks on case backs

So these two special Belles do fit into the scheme as well :)

I have justed checked my 6138 caseback archive (though with 170 pics not even as large as the Belle-DB, but it should do). These, also being Suwa watches, do also all carry either an 'A' or 'J' mark.
Will do a model-specific 6138 study and continue on 701x and Four Handers tomorrow, this mystery MUST be solved >:D

Best,
Hermann
 

·
Registered
Joined
·
4,550 Posts
Re: Does anyone know the definitive answer to the "X".."J" Japan marks on case backs

Go Hermann Poirot..... Awesome..
 

·
Registered
Joined
·
2,201 Posts
Re: Does anyone know the definitive answer to the "X".."J" Japan marks on case backs

@ AJ, Tiger:

I did not get that - what are you talking about?

;)

Best,
Hermann
 

·
Registered
Joined
·
4,550 Posts
Re: Does anyone know the definitive answer to the "X".."J" Japan marks on case backs

TheTigerUK said:
English humour Herman ??? ;)

But basically it was praise for a great job :)

:iagree: Sorry, Poirot was a fictional French investigator, Hercule Poirot to be exact, from an English TV show.....
 

·
Registered
Joined
·
2 Posts
Re: Does anyone know the definitive answer to the "X".."J" Japan marks on case backs

Technoman said:
:iagree: Sorry, Poirot was a fictional French investigator, Hercule Poirot to be exact, from an English TV show.....
Hercule Poirot was definitely NOT French. He was a French speaking Belgian.
 

·
Registered
Joined
·
4,550 Posts
Re: Does anyone know the definitive answer to the "X".."J" Japan marks on case backs

kevin said:
Hercule Poirot was definitely NOT French. He was a French speaking Belgian.

More interestingly, it seems he was more of an English speaking with a french accent Belgian, but ostensibly you are correct....
 

·
Registered
Joined
·
2,201 Posts
Re: Does anyone know the definitive answer to the "X".."J" Japan marks on case backs

Gentlemen,

Here is now the first update of my 'Japan X' study, dealing with the calibre 6117 Four Handers.
The used data set were approx. 80 casebacks with unique case (sub)number/production date combinations and include (to my knowledge) all the case subvariants. I have tried to be more concise this time, and summarized the data in a table:


 
As can be seen in table 1, the first models on the market where the 6010/6019 World Times, carrying a ‘Japan J’ mark throughout, to be followed by the 8000/8009 Navigator Timers, carrying a ‘Japan U’ mark throughout. Next came the 6400/6409 World Times and the 6410/6419 Navigator Timers, initially all carrying a ‘Japan J’ mark, but mark of the whole 64xx line changed from J to F and vice versa several times over the production period. Then, there is also an (apparently) rare oddball, a 6420 model, carrying a ‘Japan F’ mark.

What could be an interpretation of this? In my opinion, it fortifies hypothesis 3 from my previous post: it would make sense, that the mark refers to a production line. While the line was not changed for the 601x/800x series, production of the 64xx was switched several times over the production period from line J to line F and vice versa – maybe to increase plant utilization.

I have also included the number of casebacks in my archive for each model plus a relative content for each model, which can be used as a ballpark figure as to which models where produced in large quantities – and which are rare.

Best,
Hermann
 

·
Registered
Joined
·
2,201 Posts
Re: Does anyone know the definitive answer to the "X".."J" Japan marks on case backs

TheTigerUK said:
English humour Herman ??? ;)

But basically it was praise for a great job :)
Then all I can say is 'thank you' :)

Best,
Hermann
 

·
Registered
Joined
·
2,201 Posts
Re: Does anyone know the definitive answer to the "X".."J" Japan marks on case backs

Next is a study of the 5619 calibre series watches!

Since this movement is apparently very rare, the data set is only a very modest 11 casebacks at the moment...

:'(

If anyone has some caseback pics of this model, kindly forward them to me please!
Anyway, here are the data, nothing much interesting, all 5619 case subvariants appear to have been manufactured with a 'Japan A' mark:



Best,
Hermann
 

·
Registered
Joined
·
2,201 Posts
Re: Does anyone know the definitive answer to the "X".."J" Japan marks on case backs

Gents,

Next is a study of the calibre 6138 chronographs. I must admit that I only included photographs of watches that I want in my collection in thearchive - thus, the 001x, 002x, 004x, 700x and 803x lines are not included in the study. The data set is a nifty 180 casebacks with unique case (sub)number/production date combinations, however. Data are summarized in the table below, with case (sub)variants in chronological order of first production date:



As can be seen in the table, all the 80xx series as well as the 0030 6138s were manufactured with a 'Japan A' mark throughout, and the 300x series always carry a 'Japan J' mark. Again, there is a hint, that the mark stands potentially for a production/assembly line:

As most of you are probably aware, the engravement/font etc. on the casebacks of most Vintage Seikos was changed somewhen in the 70s. I have denoted the two caseback types as 'Water Resistant I (R1 csb)' and 'Water Resistant II (R2 csb)', shown are two 6138-0030 casebacks:

R1 csb:


R2 csb:


In the table, there is a column denoted 'R2 csb first use' - and there is something interesting to that, let me explain what I mean by taking a look at the high-abundance, long-production timeframe 3002 (mark 'J'), 0030 and 8020 (both mark 'A') models: while the caseback type was changed from type R1 to type R2 somewhere around 1974, it was NEVER changed on the 3002 model until the end of production in 1977.

A plausible explaination for this: again, 'Japan X' denotes a production/assembly line, with Seiko probably updating the machines in line 'A', but not in line 'J'.

And finally, a remark concerning the abundance of the individual models. With a data set of 180 watches, I think there are some conclusions that can be drawn! There were some surprises for me there - numbers of 3002 and 8020 watches were relatively high, 8010 and 8001 low, as expected. The high occurence of 0030 models surprised me, but more so the obvious rarity of the 3005 and 3009 'Jumbo' variants!

Just my 0.002 cents, hope you are not already fed up with my wild speculations :)

701x models to follow soon!

Best,
Hermann
 
21 - 33 of 33 Posts
Top