Seiko 5G23A Technical Guide

Introduction

The Seiko 5G23A is a high-precision quartz analog movement developed by Seiko in the late 1990s to early 2000s. Belonging to the 5G series, this movement is known for its compact size, reliable performance, and dual calendar display (day and date). It was used in a variety of mid-range Seiko watches, offering both functionality and elegance in a durable, low-maintenance package.

Though less known than Seiko's 7N or 9F calibers, the 5G23A features a hacking function, quickset calendar, and manual hand alignment—features that set it apart from more basic quartz movements of the time.

Technical Specifications

• Caliber: Seiko 5G23A

• Movement Type: Quartz analog

• Functions: Hour, minute, central seconds, day, date

• Jewels: 2

• Accuracy: ±20 seconds per month

• Battery Type: SR920SW (1.5V silver oxide)

• Estimated Battery Life: ~3 years

• Hacking Seconds: Yes

• Quickset Day/Date: Yes

• Manual Reset (Zero Positioning): Yes

• Movement Diameter: ~23.5 mm

• Movement Height: ~2.8 mm

• Calendar Languages: Commonly English + Spanish or English + Kanji

• Integrated Circuit: CMOS with quartz oscillator

• Temperature Compensation: No (standard crystal)

Features Overview

Dual Calendar

The day and date complication is neatly displayed at 3 o’clock or occasionally at 6 o’clock, depending on the watch design. Both features are fully quickset, allowing for fast adjustment without the need to rotate the hands repeatedly.

• Quickset Date: Pull crown to first position and rotate clockwise

• Quickset Day: Rotate crown counterclockwise

• Avoid using the quickset functions between 9 PM and 3 AM to prevent gear damage during the calendar changeover process.

Hacking and Reset Functions

The hacking feature allows for precise time setting by stopping the seconds hand when the crown is pulled to the time-setting position.

The manual reset (zero positioning) function allows for realignment of the hands after battery replacement or shock. This ensures all hands return to their correct zero positions, maintaining aesthetic symmetry and functional accuracy.

This function is engaged by using conductive tweezers or a metal tool to briefly connect the AC (all-clear) terminal to the battery.

Compact and Durable

The 5G23A is a compact movement, optimized for use in thin or mid-sized case designs. With 2 synthetic jewels, it reduces long-term wear on key pivots and improves hand stability. It balances size, strength, and functionality for everyday watches in both casual and formal settings.

Watch Models Featuring the 5G23A

The Seiko 5G23A was used in various Seiko collections during the early 2000s, including:

• Seiko quartz dress watches

• Seiko 5 quartz variants (with calendar)

• Basic to mid-tier Seiko Selection models

• Watches with stainless steel cases, simple baton indices, and classic or military-inspired dial layouts

These watches were targeted toward wearers who appreciated durability and practicality without the complexity of mechanical movements.

Service and Maintenance

Battery Replacement

• Use SR920SW (1.5V) only.

• Typical life is ~3 years under standard use.

• After battery change, realign hands using the manual reset procedure.

Caution During Setting

• Always avoid quickset during 9 PM – 3 AM to protect the calendar mechanism.

• Avoid exposure to static electricity or magnetic fields during servicing, as the CMOS IC is sensitive.

Parts Availability

While basic parts like gaskets and batteries are still available, original calendar wheels, circuits, and gears for the 5G23A are becoming harder to source. Donor movements are the best solution for long-term restoration work.

Summary

Conclusion

The Seiko 5G23A is a reliable, well-designed quartz movement that blends functional features with slim elegance. With its full calendar, hacking, and realignment functions, it offered a superior experience over many entry-level quartz calibers. While now vintage, watches powered by this movement continue to provide dependable performance and deserve appreciation from collectors and daily wearers alike.