S. Epson Corp. Caliber Y120G

The S. Epson Corp. caliber Y120 (aka Y120G) is a small size two-handed quartz watch movement with 0 jewels. It is made in Japan. Official documentation on this caliber has date stamps as recent as 2/28/18.

This movement is referred to as a ladies movement because of its small size, but it is also found in mens watches. There is also a long stem version of this movement available for large case watches which place the movement off center.

The movement pictured here also has a hexagon shape with the number 4 inside. The meaning of this marking is still unconfirmed, but it could be a reference to the factory it was produced in. If you know anything about this, please comment below.

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

You may see the caliber Y120 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 G (Y120G).

Note: This movement is small, therefore the identifying markings are also small. For that reason, this caliber is sometimes incorrectly written as Y120Q. The G looks like a Q in some angles. It may also be written as Y12O which is also incorrect.

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 Drawings:

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.

Replacement Price:

At the time of this post, replacement prices for the Y120G were found online for about $2.92 to $9.99 USD.

Examples of watches with this movement:

The movement pictured in this caliber listing was found in a cheap $19.99 plastic NEFF watch. The picture above is what it looks like with the plastic movement holder.

Additional Resources:

• Official tech sheets
• Difference between SII, Epson, TMI, Hattori