Seiko NH34A

TABLE OF CONTENTS

Overview
Accuracy
Time Setting

Overview

The NH34A is an automatic mechanical movement from Seiko, renowned for its robustness and affordability. Featuring a 24-hour GMT complication, it allows wearers to track a second time zone, making it a practical choice for travelers and enthusiasts alike.

It operates with a 21,600 vibrations per hour beat rate and offers hacking and hand-winding capabilities. Its durability, ease of maintenance, and compatibility with various watch designs make it a favored option among watchmakers seeking a dependable GMT movement.

Specifications

Type: Automatic (Self-winding) with Manual Winding Capability
Functions: Hours, minutes and seconds in the center. 2nd time zone display / 24 h GMT in the center. Date window with quick setting.
Power Reserve: 41h
Accuracy: -20 to +40 seconds per day
Jewels: 24
Vibrations per Hour (BPH): 21,600 A/h
Hacking Function: Yes (seconds hand stops when setting the time)
Hand-Winding: Yes
Diameter: 27.40 mm
Thickness: 5.32mm
Crown Position: 3 o’clock
Date Function: Quick-set date at 3 o’clock (optional)
Day Function: No

Time Setting

Wind the Watch
Unscrew crown and pull it to position 1 and rotate clockwise 25–30 times to charge the mainspring
Set the GMT Hand
Push the crown to Position 2 and rotate clockwise to move the red GMT hand in hourly increments.
Set the DATE.
Push the crown to Position 2 and rotate CounterClockwise to move Calendar Disc.
Set the Time
Pull the crown to Position 3. Rotate clockwise or counterclockwise to set the time. The seconds hand will hack (stop).
Tighten the crown
To ensure water resistance, you must always tighten the crown before use. For watches with a screw-down crown, press the crown in while turning it clockwise until it is fully screwed down against the watch case to create a watertight sea

This movement is used in the following references

U1-GMT

U1-SPG

U4-GMT

U1-SPGS

U2-GMT

U4-GMT-MMC

U4-TS24W

U4-TS24B