Seiko 7A38 - by the numbers

I think I've pretty much 'done to death' the S.Epson Corp. / Shiojiri Ltd. YM55A (and associated Orient JCA00) in this previous thread.

I was about to tack this latest 'spot' onto the end of it, as something of a final post-script, but then I quicky realized I was looking at yet another slightly different and hitherto unidentified caliber.

Most 7Axx aficionados are familiar with the 7A28-7160 Honda F1. It's clear that Seiko have a long running partnership arrangement with Honda, which includes the current Sportura models. In between there have been a few 'oddballs' like the YM55A and YM57A variants (documented in other threads in this section). Today while browsing Yahoo Japan, I think I've spotted another 'oddball'.

The reason I initially homed in on this particular listing was because of the slightly odd crown and pusher arrangement.

Just ike the YM55A based chrono's it has one crown at 3 o'clock and 3 pushers at 2 o'clock; 8 o'clock and 10 o'clock.

The difference being that is this one is a 1/100 second chronograph - and it's definitely not a 7T59 !! 

So without further ado, here's the YJ listing (which currently only has 4 hours left to run):

http://page5.auctions.yahoo.co.jp/jp/auction/e169252542

The Japanese seller's title and brief description translates as follows:

Seiko Honda 1995 titanium 1/100 chronograph

Operation not yet confirmed (for the back cover is hard) 18mm I think bezel 35mm 1/100 Chrono carbon dial luminous dial with original titanium buckle.

Unfortunately even by zooming in, it's not possible to discern the xxxx-xxxx case-back model #. That would have been too easy. 

In fact, with a little intuitive googling, it was dead easy to figure out what it was - in a matter of minutes. I already had a good idea. 

To quote myself from above: In between there have been a few 'oddballs' like the YM55A and YM57A ....

Of course, in between the YM55A and YM57A there was the YM56A - a 1/00s chrono' movement used in 1990's Yema Rallygraf's.

My next google result provided a superb pre-written answer, which I make no apologies for copying and pasting almost verbatim:

http://www.watchprosite.com/?page=wf.forumpost&fi=876&ti=915073&pi=6293503

Amusingly enough, the thread is entitled:  Identifying a Seiko Watch, Part 2. Scroll down that page until you come to:

Now to a more obscure watch not even labeled as Seiko. This was found by my nephew while he was surfing. It had no strap on one side so he supposed the spring bar came loose while someone was in the water. I cleaned it up and got it running with a new appropriately-styled rubber strap. The second hand is jumping in 2-second increments which means it needs a battery. Might as well do it now. (time passes).

The movement says S. Epson Corp. Here's a short explanation of Seiko's corporate structure, from about 8 years ago by SJX on this site:

"Seiko consists of three independent companies; the Hattori family has shares in all of them. Seiko Corporation encompasses marketing and wholesaling watches as well as the making of clocks, golf clubs (S-Yard), precision and scientific equipment, semiconductors and optical products. Watches sold by Seiko Corp. are made by Seiko Instruments Inc. (SII). SII produces watches, micromechanical products and semiconductors. Seiko Epson is known for its printing products, but also owns Orient Watch Co. Ltd. and makes in semiconductor and optical products. Epson came about when Seiko created printers to record the time results at the 1964 Olympic Games in Tokyo, laying the foundation for Seiko Epson - Epson is derived from “son of Electronic Printer”.

Okay, end of history lesson.

A new battery was needed, I took pictures, then cleaned movement and case with Rodico, remembered to put the movement spacer back in before closing the case, put Seiko silicone grease on the case gasket for better sealing, and reset all hands to zero. Reset the time. Total service time, ten minutes.

For those readers not familar with the Yema Rallygraf which I referred to in my previous post, their yellow dial is pretty distinctive.

I remember seeing this this wrist shot of one posted on a number watch forums - going back to 2009:

Here's a couple of stock images:

Confusingly, the Yema model code for this one was YM039, but their case-backs are stamped YM56 (per the movement used).

There is however one major difference between the S.Epson Corp. YM56A movement and the YM55A discussed in the other thread ....

And that is that there exists a direct equivalent Seiko branded version of the YM56A movement - the Seiko 7T52B.

Strangely, there doesn't seem to be any previous reference to them (other than a passing mention) on this forum. 

So I'll quickly try to rectify that. 

Going back to 2009, before I'd made a conscious decision to 'restrict' my collection only to 7A38's (and re-branded versions thereof),

I certainly looked at and considered buying one of them. Here's just a few images I saved from eBay (and elsewhere) in 2009 / 10:

7T52-6A20:

7T52-6A50:

7T52-6B00:

7T52-7000:

7T52-7A09:

Indeed with it's simpler (no GMT hand or day window) dial layout and only one crown, the 7T52 is effectively a 'cut-down' version of the 7T59 .... and all the better for it. Make me wonder why I never got around to buying one, way back when I was looking. 

That small selection of photos I've uploaded is just 'the tip of the iceberg', incidentally. There are lots of other Seiko 7T52 variants to choose from. A search on Seiko Oceania's database on (calibre) 7T52 returns 77 lines - compared to 56 of the more popular 7T59.

Other than myself, very few seem to have made the connection between the S.Epson Corp. YM56A and Seiko's own 7T52 movement.

Here's one Japanese blogger who has: http://www.akitan.net/watch/sub/not.htm The top segment of that page translates as:

YM56 Alba Epsilon 1/100 second chronograph

Hundredths of a second of 1998 production is looks chronograph.

1/100 second chronograph '94 or later, but had not been produced, now, it appears in a new product lineup.

Placement of the caliber's the same as the 7T52, but YM56. The difference on the specs even month difference ± 20 seconds (7T52 is ± 15 seconds per month) is about that. 12:00 position of the register is the same place that rotates in the ultra-high speed.

Out of curiosity, I tried keying YM56 (with and without 'A') into Seiko Oceania's database. It effectively returned only one result:

The Alba Epsilon YM56-0A30 from the previous post !  Not a surprise really - Alba is an 'official' Seiko sub-brand.

Needless to say, no Honda, Mazda nor Yema RallyGraf model codes (and possibly others besides). But now we know.