Seiko 3703B – Technical Guide

The Seiko 3703B is a high-precision Twin Quartz movement, part of Seiko's elite range of thermo-compensated quartz calibers developed in the late 1970s and early 1980s. This caliber belongs to the 3700-series, which includes some of the most accurate analog quartz movements Seiko has ever produced. The 3703B was typically used in Seiko's premium models—especially within the Grand Quartz and Superior lines.

This guide outlines the movement’s technical specifications, core features, service procedures, and performance characteristics.

Movement Overview

• Caliber: Seiko 3703B

• Type: Analog Quartz (Twin Quartz, thermo-compensated)

• Functions: Hours, Minutes, Central Seconds, Date

• Jewels: 2

• Battery Type: SR44W (357)

• Battery Life: ~2 years

• Frequency: 32,768 Hz (×2 crystals – one timekeeping, one thermal reference)

• Accuracy: ±10 seconds per year

• Calendar Mechanism: Quickset date via crown pull/push

This B-variant is a refined version of the earlier 3703A, likely featuring minor updates to the integrated circuit or layout for improved stability or ease of assembly.

Key Features

1. Twin Quartz Technology

The hallmark of the 3703B is Seiko’s Twin Quartz system:

• One quartz crystal serves for timekeeping.

• A second quartz crystal functions as a temperature sensor, compensating for thermal drift.

This design improves accuracy dramatically over standard quartz movements, as quartz oscillators are susceptible to temperature-related frequency shifts.

2. Date Display

Unlike the 3702A or 3702B (which have no date), the 3703B includes a quickset date window, advancing with a half pull of the crown.

3. High-End Construction

Movements in this class were cased in premium stainless steel or gold-capped cases, often with high-quality finishing, solid bracelets, and applied dial furniture.

Technical Specifications

Battery Replacement & Servicing

Battery Change Procedure:

1. Open the case back (usually screw-down type).

2. Use non-metallic tweezers to remove the SR44W battery.

3. Clean the battery contact terminals with pegwood or a fiberglass brush.

4. Insert the new battery with correct polarity.

5. Observe movement for immediate operation.

6. Reset the time and date via the crown.

Service Notes:

• These are non-user-serviceable for regulation—timing adjustment is factory-set.

• If the second hand skips or moves erratically, coil damage or IC failure is likely.

• Avoid magnets and excessive heat, which can disrupt the compensation circuit.

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