NH38 Automatic Movement

The Seiko NH38 is a reliable Japanese automatic movement designed for watches without a date display. Its clean, no-date design makes it a popular choice for open-heart and minimalist dials while delivering the dependable performance Seiko movements are known for. It features both automatic and manual winding, as well as hacking seconds for precise time setting.

Specifications

  • Movement: Seiko NH38
  • Type: Automatic
  • Origin: Japan
  • Jewels: 24
  • Power Reserve: Approximately 41 hours
  • Frequency: 21,600 vibrations per hour (3 Hz)
  • Functions:
    • Hours
    • Minutes
    • Seconds
  • Hand Winding: Yes
  • Hacking Seconds: Yes
  • Date Display: No

How to Use

Starting Your Watch

If your watch has stopped:

  1. Ensure the crown is fully pushed in.
  2. Turn the crown clockwise 20–30 times.
  3. The watch will begin running.
  4. Wear the watch regularly to keep it wound automatically.

A fully wound NH38 has a power reserve of approximately 41 hours.

Crown Positions

The NH38 has two operating positions, making it one of the simplest automatic movements to use.

Position 0 – Normal Position

The crown is fully pushed in against the case.

Function:

  • Manual winding

Turn the crown clockwise to wind the movement.

Position 1 – Time Setting

Pull the crown out until you feel one click.

Function:

  • Set the time

The seconds hand will stop while the crown is in this position, allowing you to set the time accurately.

How Do I Know Which Position I'm In?

Position 0

  • The crown is fully against the watch case.
  • You can wind the watch by turning the crown clockwise.

Position 1

  • Pull the crown out gently until you feel one click.
  • The crown will sit slightly away from the case.
  • This is the furthest position the crown can be pulled.

Since the NH38 has no date function, there is no second click or date-setting position.

Setting the Time

  1. Pull the crown to Position 1.
  2. Turn the crown until the correct time is displayed.
  3. Push the crown back in to resume normal operation.

Care Tips

  • Wind the watch before wearing it if it has stopped.
  • Keep the crown fully pushed in when not adjusting the time.
  • Avoid exposing the watch to strong magnetic fields.
  • Clean the case and bracelet regularly with a soft microfiber cloth.
  • Service the movement approximately every 5–7 years for optimal performance.

Frequently Asked Questions

Can I overwind the NH38?

No. The NH38 uses a slipping mainspring that prevents overwinding during normal manual winding.

Why did my watch stop?

Automatic watches are powered by movement. If the watch hasn't been worn for an extended period, simply wind it manually and reset the time.

Does the NH38 have a date?

No. The NH38 is a no-date movement, giving the dial a clean, symmetrical appearance.

How accurate is the NH38?

Like all mechanical movements, accuracy can vary depending on wear, temperature, and position. Small daily variations are normal.

Need Help?

Need assistance setting up your watch or have a question about your movement?

Our support team is here to help.

📧 support@monomods.com

Please include your order number and, if possible, a photo or short video of your watch so we can assist you as quickly as possible.