Seiko 7A38 - by the numbers

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Forum Home > 7Axx General Discussion Area > Sticky: Seiko 7A28 / 7A38 / 7A48 / 7Axx Simple Do-it-Yourself Production Date Calculator

Seiko7A38
Site Owner
Posts: 8886

I really find it hard to believe there's a need for such a topic, but apparently it exists. Regular readers / members look away now. 


Recently I've been running some analyses on incoming google searches that have brought visitors to the forum.

Over the last 28 days, 5 different visitors have arrived at various topics, trying to date their Seiko 7Axx's !

Earlier today, a UK visitor arrived (at a competely inappropriate thread) by googling:

what is the age of my seiko 7a38-7070 ao chronograph watches?


The original link to John Gauch's Seiko Production Date Calculator still exists: http://www.csce.uark.edu/~jgauch/photos/seiko.html 

- now re-hosted by SCWF: http://timeuniverse.com/photodatabase/seiko.html but unfortunately neither appears to work any more. :(

Others have come up with alternative Excel-based solutions.

See: http://www.thewatchforum.co.uk/index.php?showtopic=33736&view=findpost&p=703869 (clicking on embedded link downloads).


But to work out the date of manufacture of a Seiko 7Axx (from the case-back 6-digit serial number), you don't need a calculator. 

In fact it couldn't be easier. 


November 22, 2012 at 11:20 AM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 8886
All you need to remember is:

1) that the first digit of the 6-digit serial number gives you the last digit of the year, and
2) the second digit of the 6-digit serial number gives the month within that year, where:

1 = January
2 = February
3 = March
4 = April
5 = May
6 = June
7 = July
8 = August
9 = September
O = October
N = November
D = December

The last 4 digits are the production unit number for that caliber operation, within that month and year (up to a maximum of 9999).

Seiko 7Axx's were officially produced (by Seiko*) from 1983 to 1989, although a number of 7A28's were manufactured in late 1982.

Here's a recent albeit rather short SCWF thread on the subject: http://www.thewatchsite.com/index.php/topic,31094.html

and a more comprehensive thread on the old Network54 SCWF: http://www.network54.com/Forum/78440/thread/1238452999/


Seiko 7A38 serial numbers seen have ranged from 38xxxx = August 1983 - the earliest models seen being 7A38-701B 'Vulcans' ....

through to 99xxxx = September 1989 - for ZFM models 7A38-7085 and 7A38-7295 produced by Seiko's Brazilian offshore operation.


*The French Seiko subsidiary C.G.H. were still producing Yema N8's using re-branded (Shimauchi V906) movements up to 1994.


November 22, 2012 at 11:45 AM Flag Quote & Reply

whitemonster
Member
Posts: 87

This is great! Very useful!

November 22, 2012 at 1:17 PM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 8886

Here's a couple of quick examples to illustrate - both eBay images, and not the best quality, but the serial numbers are legible:


The earliest 7A38 I've ever seen - which I bought, in November 2009, belonging to my 7A38-701B 'Vulcan':



The serial number 383261 dates it to August 1983, but it certainly wasn't the 3261st 7A38-701B Vulcan produced !!

It's likely that the 0001-9999 serial number range for August 1983 was shared with then concurrent 7A28 production.


The 'newest' 7A38 serial number I've ever seen was in an eBay listing by José 'Watchcooking' Sotto, back in June 2009:




It was on a well-worn black chrome coated 7A38-7295, fitted with a leather strap in place of the original bracelet. The -7295 was the Brazilian offshore produced version of the 7A38-7290. You can just make out the ZFM stampings in the middle of the case-back.

The serial number 990511 dates it to September 1989. Has anyone seen any older or newer Seiko 7A38's than these two ? 

November 22, 2012 at 1:53 PM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 8886

Incidentally, I just had a quick scroll through my Excel spreadsheet of my 7A38 collection and ....



The newest 'Made in Japan' 7A38 I own is a gold-tone 7A38-7289, with a serial number 965611 - meaning manufactured in June 1989.

November 22, 2012 at 4:29 PM Flag Quote & Reply

brian dawes
Member
Posts: 1

dear sir i have a seiko 7a34 7010 cant find much about 34 series brian

December 22, 2012 at 2:38 AM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 8886

Hello, Brian, and welcome to the forum. :)

You're correct in that there doesn't (yet) appear be a single topic on the forum dedicated to the Seiko 7A34. :(

However, they are mentioned, on numerous occasions in various threads in different sections of the forum. ;)

The 7A34, in either -7000 or -701x case styles isn't particularly popular with collectors, for a couple of reasons:

Their generally dressy styling and the positioning of the date window at 12 o'clock, which is obscured by the sweep second hand.

The 7A34(A) movement is in effect, a cut-down version of the far more popular 7A38(A) without the latter's day wheel complication.

Seiko re-worked the 7A34(A) movement, by re-locating the date window to 4:30 for use in the Jean Lassale Thalassa 7A74 chrono.

A few forum members, including Andre ('nova'), Simon ('Sir Alan') and myself have customised our 7A34's using 7A38 movements. 8)


As far as the subject matter of this topic is concerned, the D-I-Y date calculator works just as well for a 7A34-7010 as any other 7Axx.

December 22, 2012 at 6:55 AM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 8886

The original link to John Gauch's Seiko Production Date Calculator still exists: http://www.csce.uark.edu/~jgauch/photos/seiko.html

- now re-hosted by SCWF: http://timeuniverse.com/photodatabase/seiko.html but unfortunately neither appears to work any more. :(


According to John Gauch's post on SCWF, a couple of weeks ago: http://thewatchsite.com/index.php/topic,43462.msg311180.html

Author Topic: Seiko Watch Production Date Calculator is ALIVE again

has recently (finally) been repaired: http://www.csce.uark.edu/~jgauch/photos/seiko/ Not that us Seiko 7Axx owners actually need it. :P

April 5, 2013 at 9:02 AM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 8886

The earliest 7A38 I've ever seen - which I bought, in November 2009, belonging to my 7A38-701B 'Vulcan' ....

The serial number 383261 dates it to August 1983, but it certainly wasn't the 3261st 7A38-701B Vulcan produced !!

It's likely that the 0001-9999 serial number range for August 1983 was shared with then concurrent 7A28 production.


Interestingly, I was trading PM's with a chap named Chris from WatchUseek earlier today, talking about his 7A48-7000.

In his reply he wrote: Serial no 383474 - do you know how old that would be?

Now I'd always assumed that the 7A48's were introduced a year after the 7A38's - in 1984, the date of this ad campaign:




Presuming Chris has read it correctly, his 7A48 was also manufactured in August 1983. So a very early production example.

Seems you learn something every day ! 

 

June 9, 2013 at 6:55 AM Flag Quote & Reply

fmc000
Member
Posts: 54

Hello Paul,

my 7A48-701A AKA SPV002 is even older, being a June 1983 (368904).

--

My Seiko chronos: SPV002 - SDX008J1 - SFA005J1 - PSZ006P1

June 9, 2013 at 7:43 AM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 8886

Thanks for that input Fabio. ;)

Can't say I'd previously taken a lot of notice of 7A48 caseback serial numbers before, but now I've looked at the few photos I'd kept on file, I've found more 36xxxx's: 7A48-7010's and -701A's manufactured in June 1983. This one was listed on eBay in November 2012.



Seems that 7A48 production pre-dates 7A38 production by a couple of months. Something that would never have occurred to me. 


June 9, 2013 at 8:03 AM Flag Quote & Reply

SuperJ
Member
Posts: 8

Guys, I have some interesting news for you.

I recently bought a 7A28-7029. Since it had a few minor scratches on the glass, I wanted to have it replaced by the local Seiko representation. They came back and offered me to replace the complete case, since they had a NOS left.

I agreed, and now it is really NOS, no scratches at all on the case and on the strap too, like new.

Now the interesting thing, since the case was replaced, it also came with a new back cover. The SN of this one is: 150007


This would mean now, that it was either produced in 1981 (May) or in 1991.

You decide, which year makes more sense.

November 21, 2013 at 5:55 AM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 8886

Welcome aboard - and thanks for your input. It certainly is an interesting first post ! :)

I'd tend to go with 1991, because Seiko didn't start manufacturing 7Axx's until late 1982 and the first 7A38's in August 1983.

The 7A38-7029 had probably one of the longest production runs of any model, because it was a popular seller ....

But as you'll have read, May 1991 is a long time after (offshore) 7A38 production appears to have ceased (September 1989).

Not that I doubt your word, but would it be possible for you to post photo(s) of the watch - particularly the case back ? 


By the way, you say 'NOS', but did your replacement case (and bracelet) come from a complete new watch or a sample case ?

If it's a sample case, it will have [SAMPLE] stamped on it somewhere, like this:




Incidentally, that photo (and 7A38-7029 sample case) belong to a forum member Harry (a.k.a. 'whitemonster'). I've checked my photo folder and all such 7A38-7029 sample cases appear to have 39xxxx serial numbers, so were manufactured in September 1983.


November 21, 2013 at 6:14 AM Flag Quote & Reply

SuperJ
Member
Posts: 8

Hi,

It was ordered from Seiko internally, so it is a new case, no sample. The strap was already without scratches, when I bought it.

Here is the photo of the case back.


November 21, 2013 at 6:54 AM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 8886

My bad - and my apologies. I mis-read your post as 7A38-7029, when you actually wrote 7A28-7029.  Bit of a difference there. :roll:


Your photo link didn't work properly, so I've edited your post and re-hosted your photo in my PhotoBucket  - it was quicker and easier (for me) than trying to figure out how to link from postimage.org.


Wow ! :o


Being a 7A28-7029, that sheds a different light on it. Athough that model was also an extemely popular seller, particularly in the States, I'd be more inclined to go with May 1981, which makes that watch VERY early production indeed - if not a pre-production example ! 




It may not quite be the world's first analogue quartz chronograph - but it's quite possibly the 7th ever produced !! 


November 21, 2013 at 7:06 AM Flag Quote & Reply

SuperJ
Member
Posts: 8

Thanks for helping out with the image.

I also think that it fits more to 1981 than to 1991. And since it is a very low number (0007), it could be exactly as you stated.

I am really happy with it, since it is now 'NOS'.


November 21, 2013 at 8:24 AM Flag Quote & Reply

SuperJ
Member
Posts: 8

Do you probably know, what the difference is between a 7A28-7020 and a 7A28-7029, both are goldish.

November 21, 2013 at 1:56 PM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 8886

See this thread (which is discussing a Franken):

http://www.seiko7a38.com/apps/forums/topics/show/9249187-a-rare-7a28-variant-or-another-deceptively-described-franken-

A 7A28-7020 can be all stainless with a white dial (SPR007) or two-tone with a dark metallic black-ish coloured dial (SPR010).

The 7A28-7029 is always gold-plated all over with a gold dial (SPR014).

The 9 on the end of the case number designates a US market model.

November 21, 2013 at 2:05 PM Flag Quote & Reply

SuperJ
Member
Posts: 8

Thanks. Was there also a 7A28-7020 in all gold (case and strap)?


November 21, 2013 at 2:36 PM Flag Quote & Reply

Seiko7A38
Site Owner
Posts: 8886

Not that I've ever seen, No. There was an all-gold plated gold dialed 7A38-7060 which looks similar though (but with day / date).

November 21, 2013 at 2:42 PM Flag Quote & Reply

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