Seiko Epson Hattori Japan caliber Y121 Watch Movement

S. Epson Corp. Caliber Y121E

Seiko Epson Hattori Japan caliber Y121 Watch Movement

Manufacturer S. Epson Corp. (Seiko/Hatori)
Caliber Number Y121E
Type Quartz
Size 6 3/4”’ x 8”’ (15.3mm x 18.1mm)
Height 2.70mm (4.5mm to the top of the second hand pinion)
Battery Cell Number 377
Frequency Unknown (please comment below)
Quartz Type Tuning fork type quartz crystal
Stem 354786 (tap 10)
Hand Sizes 1.10/.65/.20
Jewels 0
Functions Hours, minutes, central seconds
Country of Manufacture Japan
Known Models Add in the comments below…

The S. Epson Corp. caliber Y121 (aka Y121E) is a 0 jewels quartz movement. It is made in Japan. 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.

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Loiz
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Loiz

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

Cris
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Cris

I have a S. Epson Y121E

bjaast
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bjaast

RELIC ZR33034 uses this caliber.

Glen Stephenson
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Glen Stephenson

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

Ian Lavender
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Ian Lavender

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

Ragnar B Sulejewski
Guest

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

Glen Stephenson
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Glen Stephenson

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

Fernando
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Fernando

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

Cris
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Cris

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

Splodgie
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Splodgie

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 appreciated.

Chris
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Chris

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
Guest
Splodgie

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 of times the hand never went out of sync because of the speed I was turning the hands.

Chris
Guest
Chris

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
Guest
Splodgie

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, I can get a Epson Y121E-1 at a good price and P&P, so it looks like I will have to get the Y121E-1 and put… Read more »

Manuel Ferreira
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Manuel Ferreira

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

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