Seiko 5P23A – Technical Guide

Introduction

The Seiko 5P23A is a quartz analog movement with dual time functionality, closely related to the Seiko 5P22A. Introduced in the 1990s, the 5P23A adds practical day-date display functionality to its core dual timekeeping features, making it ideal for business travelers and users who need to track two time zones while retaining a full calendar.

This movement is compact, efficient, and user-friendly, and was widely used in Seiko Dress and Travel Quartz models. Its ease of use and low maintenance needs have made it a favorite among wearers seeking accuracy and function in one timepiece.

Technical Specifications

Functional Overview

Dual Time Display

The 5P23A offers a second time zone via a separate sub-dial or an additional hour hand (depending on model). This secondary display is independently adjustable and operates in 12-hour format.

• Main hands: Show local time (hours, minutes, seconds)

• Sub-dial or fourth hand: Indicates time in a second time zone

Calendar Functionality

The movement features a day-date calendar, typically shown in a side-by-side window at 3 o’clock.

• Day: Often bilingual (e.g., English + Spanish or English + Kanji)

• Date: Numeric, 1–31

• Both can be quickset via the crown.

Setting Instructions

Time Setting

• Crown Position 0 (pushed in): Normal operation

• Crown Position 1 (first click):

  • Rotate clockwise → quickset date

  • Rotate counterclockwise → quickset day

• Crown Position 2 (fully pulled out):

  • Set main time (hours, minutes); seconds hand stops (hacking)

Second Time Zone

• Adjusted using either:

  • Independent pusher (often located at 2 or 4 o’clock)

  • Rotating the crown in an alternate position (depends on case design)

Battery and Power

• Uses SR621SW (1.55V) silver oxide battery

• Battery life: ~3 years under standard conditions

• No end-of-life (EOL) indicator — the watch simply stops when voltage drops

Always use non-metallic tweezers during installation to avoid static discharge

Manual Reset (After Battery Replacement)

After changing the battery or if hands become misaligned:

1. Identify the AC (All Clear) contact pin near the battery.

2. Use non-metallic tweezers to short the AC pin to the positive side of the battery for 2–3 seconds.

3. The movement will reset and resume normal function.

Servicing Notes

• Avoid lubricating parts unless directed in Seiko’s technical service bulletin.

• Clean contact points with non-corrosive solvent (e.g., isopropyl alcohol).

• Replace gaskets during service and pressure test after reassembly if water-resistant.

• Avoid strong magnets and static discharge near the quartz IC.

Common Issues & Solutions

Watch Models Using the 5P23A

The 5P23A was featured in:

• Seiko Dual Time Quartz watches

• World Timer and International models

• Classic dress watches with sub-dials at 6 or 9 o’clock

• Cases in stainless steel, gold-tone, or two-tone

• Often marked on the caseback with "5P23-xxxx"

Many models were sold in Japan, Asia, and Europe, especially during the 1990s.

Summary Table

Conclusion

The Seiko 5P23A is a thoughtfully designed quartz movement built for functionality and practicality, offering dual time tracking with day-date display in a slim, low-maintenance package. Ideal for travelers or professionals managing multiple time zones, the 5P23A remains a useful and reliable caliber in Seiko's legacy of global timekeeping.