Seiko Epson Hattori Japan caliber Y121 Watch Movement

S. Epson Corp. Caliber Y121E

Seiko Epson Hattori Japan caliber Y121 Watch Movement

ManufacturerS. Epson Corp. (Seiko/Hatori)
Caliber NumberY121, Y121E
TypeQuartz
Lignes6 3/4”’ x 8”’
Diameter
15.3mm x 18.2mm
Casing Diameter
15.3mm x 17.8mm
Height2.99mm (4.5mm to the top of the second hand pinion)
Jewels
0
Battery Cell Number377 (SR626SW 1.55V)
Battery Life
Estimated 3 years
Frequency32,768 Hz
Quartz TypeTuning fork type quartz crystal
Accuracy
+/- 20 seconds per month
Stem0354788 or 0354787
Hand Sizes1.10mm / .65mm / .20mm
FunctionsHours, minutes, central seconds
Country of ManufactureJapan
Known Watches Various Armitron, Nine West, DMQ, Luck Brand, Vince Camuto, Sutton New York, Guess, Liz Claiborne, Anne Klein ladies watches, etc (Too many to list, please add your watch in the comments below…)

The S. Epson Corp. caliber Y121 (aka Y121E) is a 0 jewels quartz movement. It is made in Japan. Official documentation on this caliber has date stamps as recent as 2/28/18.

Variations A, B, C, D, E, F, etc:

You may see the caliber Y121 with different letters on the end. The letters indicate evolution versions of the caliber. As each letter advances, there may be slight changes made. They are all based on the same Y121 caliber and should work interchangeably.

As of the latest tech sheets dated 11/30/18, the letter variation is F (Y121F).

Accuracy:

S. Epson officially claims that the accuracy of this movement is +/- 20 seconds per month, while worn on the wrist in normal operating conditions and temperatures. The operating temperature range is -5 C to 50 C.

Technical Drawing:

Epson Seiko Caliber Y121 Drawing

Stem Removal:

The word “PUSH” with an arrow right facing is etched on the movement near the stem. The arrow is pointing to the stem release mechanism. It is a metal tab with a small indentation or dimple. Gently press that with your tool (tweezers, peg wood, or even a toothpick) and pull the stem out. Do not push too hard.

Seiko Epson Caliber Y121e Stem Removal Push

Replacement Cost:

At the time of this post, we found replacement costs of $5.50 USD.

From Wikipedia (link):

The roots of Seiko Epson Corporation go back to a company called Daiwa Kogyo, Ltd. which was founded in 1942 by Hisao Yamazaki, a local clock shop owner and former employee of K. Hattori, in Suwa, Nagano, Japan. Daiwa Kogyo was supported by an investment from the Hattori family (founder of the Seiko Group) and began as a manufacturer of watch parts for Daini Seikosha (currently Seiko Instruments). The company started operation in a 2,500-square-foot (230 m2) renovated miso storehouse with 22 employees.

In 1943, Daini Seikosha established a factory in Suwa for manufacturing Seiko watches with Daiwa Kogyo. In 1959, the Suwa Factory of Daini Seikosha was split up and merged into Daiwa Kogyo to form Suwa Seikosha Co., Ltd: the forerunner of the Seiko Epson Corporation. The company has developed many timepiece technologies. In particular, it developed the world’s first portable quartz timer (Seiko QC-951) in 1963, the world’s first quartz watch (Seiko Quartz Astron 35SQ) in 1969, the first automatic power generating quartz watch (Seiko Auto-Quartz) in 1988 and the Spring Drive watch movement in 1999.

The watch business is the root of the company’s micromechatronics technologies and still one of the major businesses for Seiko Epson today although it accounts for less than one-tenth of total revenues. The watches made by the company are sold through the Seiko Watch Corporation, a subsidiary of Seiko Holdings Corporation.

In 2009, the company became fully owner of Orient Watch Co., Ltd., the one of the largest timepiece manufacturers in Japan.

Additional Resources:

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Loiz
Loiz
2 years ago

i would like to buy 40 Y121E machines how can i contanc with someone?

Cris
Cris
2 years ago
Reply to  Loiz

I have a S. Epson Y121E

bjaast
bjaast
2 years ago

RELIC ZR33034 uses this caliber.

Glen Stephenson
Glen Stephenson
2 years ago

Hi has any one got a Epson Y185 B electronic circuit or working Movement Thank You Glen Stephenson Australia

Ian Lavender
Ian Lavender
2 years ago

Chews through LR626/377 batteries in a Lacoste Goa watch. Unsure why?

Ragnar B Sulejewski
Ragnar B Sulejewski
2 years ago

Where do I find the user manual for Y121 ES/BJ3475?

Glen Stephenson
Glen Stephenson
2 years ago

Hi still looking for Epson Y185b complete movement or electronic mt wil purchase second hand/pre used if working Thank You Glen Stephenson Australia

Sal
Sal
4 months ago

Hi, did you find the Y185B ? I’m willing to purchase one as well if you have any info please let me know. Thanks in advance

Fernando
Fernando
2 years ago

hi looking to buy a wrist watch made by your corporation a Mexican soccer team America your input is appreciated

Cris
Cris
2 years ago
Reply to  Fernando

I have a S. Epson Corp Y121E
(832) 425-7989

Splodgie
Splodgie
2 years ago

I have this movement in a Guess watch 2 years old., After having the battery replaced it has a very odd problem, The second and minute hands keep perfect time. but the hour hand (that is fitted correctly and not loose) looses 3 hrs a day every day. the tine adjuster was removed and it’s still the same. The hand movement is silky smooth in operation. any advice on how to cure this would be… Read more »

Chris
Chris
2 years ago
Reply to  Splodgie

This might sounds silly, but are you sure that the hour hand isn’t loose? Does it change its position when you shake your watch or bump it?

Splodgie
Splodgie
2 years ago
Reply to  Chris

Hi Chris, Thanks for the reply and I have found the problem, The plastic white gear that drives the hour hand has a miss-formed tooth on it. If i look at the end of the gear all the teeth are there, but when looking at the teeth from the side one tooth is 85%ish missing. it’s been miss-manufactured that way. If I pulled the winder to adjust the time and spun the hands round lots… Read more »

Chris
Chris
2 years ago
Reply to  Splodgie

That is really interesting! For two years there wasn’t a problem until you changed the battery? I wonder what could have caused this gear issue since the battery change? What are you going to do now?

Splodgie
Splodgie
2 years ago
Reply to  Chris

Hi, It’s the Mrs watch and when it started loosing time She took it into a Jewelers to have the battery replaced, when She got it back that’s when I was told that it was loosing even more time from a few minuets to hours a day, that’s when I got involved. It’s a Epson Y121E-4 and I cannot find one at a sensible price as the postage is 4x the price of the movement,… Read more »

Manuel Ferreira
Manuel Ferreira
1 year ago

For the purpose of replacing the button cell, I discovered the S. Epson Corp. Caliber Y121E quartz movement inside my beautiful Armitron square case Swarvosky diamond indices dress watch model # 20/4507SV. Thank you all for the information on this great website,

S. Epson Corp. Caliber Y121E = Armitron #20/4507SV

Carl Bock
Carl Bock
1 year ago

I have a watch there is a purple cross no jewels watch with the same type of movement you guys are talking about it opens and closes like a rocket purple

Carl Bock
Carl Bock
1 year ago

I have what looks like an old watch with the same type of movement you guys are talking about it’s a purple watch quartz movement it’s like a rocket it opens and closes like a lock it it’s about 2 inches long anything no damage does anybody know anything about it

Carl Bock
Carl Bock
1 year ago

Of course this watch locket made in Japan s Epson Corporation y121e it looks more. 1212

Carl Bock
Carl Bock
1 year ago

It does say y121e no Jewel purple locket watch

German Delvalle
German Delvalle
1 year ago

I need Y121E mov 7.3 from bottom to top of second hand. Special watch

Chris
Chris
1 year ago

What is the part that says push used for? What does it do?

Barry FERGUSON
Barry FERGUSON
11 months ago

After replace battery, is there a procedure to restart the watch
or should it happen automatically?

Angelo Hammond
Angelo Hammond
11 months ago
Reply to  Barry FERGUSON

Mine was plug n play. No AC reset needed. I don’t think there’s even a way to do it. I have a chronograph on the other hand that needed a jump.

Barry FERGUSON
Barry FERGUSON
11 months ago

Is it possible for mere mortals to get a tech sheet?
Is it possible to regulate this movement?
I notice that perrinpartswatch.com lists this
movement for $2.68 Canadian.

Mats Berntsen
Mats Berntsen
5 months ago
Reply to  Barry FERGUSON

I am a mere mortal and I got the tech sheet linked up top in the information.

MAYANK MARUDHAR
MAYANK MARUDHAR
10 months ago

Casio watch ENTICER MTP-E130 use VX65E EPSON

Callie
Callie
8 months ago

I looking to buy the S.Epson clock reference AL2l E or equal

Hugo
Hugo
8 months ago

Hola tengo un reloj de Aldo y121E cuanto cuesta monetariamnete

andre mormile
andre mormile
5 months ago

Greetings, I was examining a les must de argent swiss Cartier wrist watch…it had everything expected the sapphire face, the proper back information (exception the flower pattern in the upper left corner differed from others I’ve looked at), the gold plating over the sterling was excellent…so I moved on and opened the back after removing 4 perfect screws and starring back at me was a Japan S. Epson Corp Y121E quartz engine. Anyone else have… Read more »

Mats Berntsen
Mats Berntsen
5 months ago
Reply to  andre mormile

Some of these small Seiko are used in fakes because they are all but $5 bucks. Maybe what I am thinking of is a different movement because they usually don’t have a metal back just all plastic and those are even cheaper. If you believe everything else on your watch is real then the maybe the movement went bad and someone replaced it. I don’t know why they would go through all the trouble to… Read more »

andre mormile
andre mormile
5 months ago
Reply to  Mats Berntsen

thanks for the fine insight Mats; I’ve written it up and taken photos assembled / disassembled and perhaps I’ll list it as you’ve opinioned, mostly Cartier Argent with replaced engine…

Mats Berntsen
Mats Berntsen
5 months ago
Reply to  andre mormile

Is there a way to post a picture? I am just more curious now what this Cartier looks like.

andre mormile
andre mormile
5 months ago
Reply to  Mats Berntsen

I’ve attached a few for you…have a great day…later

andre mormile
andre mormile
5 months ago
Reply to  andre mormile

Just a note…thanks for the interest..it was a great journey messing around with this watch….I hope you can access the photos; keep me posted if you have additional insight. Andre

xDiscoTech
xDiscoTech
5 months ago
Reply to  andre mormile

I had a Must De Cartier many years ago. Don’t know if it’s ok to discuss fake watches here, but Saw this thread and think there are so many red flags on the Cartier in the pics. From the back screws, markings on the back, hands, second hand, crown and white plastic movement holder to name a few. A quick search of gens and you’ll see what I mean. Again take it as a grain… Read more »

andre mormile
andre mormile
5 months ago
Reply to  xDiscoTech

Yeah…grain of salt…always learning; I hear what your saying clearly.. I appreciate getting comments positive or negative…never intended to journey down road of “fake” watches; the S. Epson Corp Y121E mechanism works great btw. Andre

Mats Berntsen
Mats Berntsen
5 months ago
Reply to  andre mormile

Pics received! It’s nice to be able to see an image of what you saw when you opened the watch. Thanks!

Glen Stephenson
Glen Stephenson
5 months ago

hi has anyone got an circuit for a epson Y185B or working movement for sale Glen Stephenson Australia

Simon Cuthbert
Simon Cuthbert
2 months ago

Hi Does anyone know where I can get a Y121E with a longer hand shaft? I bought a movement recently to replace the broken one in my watch, but the shafts on the one I was sold, where the hands attach is too short The one I was sent actually says Y121 (without the E), so I thought this was the problem, but most of the other ones I see for sale have the number… Read more »

LUTHER WHITE
LUTHER WHITE
2 months ago
Reply to  Simon Cuthbert

YES I HAVE ONE

west
west
1 month ago

In jubilee Westfalia clock key holder is Y121E.

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