Manual for NH35 seiko mod watch movement
🕰️ SEIKO NH35 MOVEMENT USER MANUAL
(For All Seiko Mods and Watches Using the NH35 Automatic Movement)
Overview
Your watch is powered by the Seiko NH35 automatic movement, a highly reliable and accurate mechanical movement used worldwide in Seiko watches and custom builds (“mods”).
It’s automatic — meaning it winds itself from wrist motion — but it can also be wound manually via the crown.
Each model may differ slightly in case design, crown type, or water resistance rating. Please read this guide carefully before operation.
Powering the Movement
1. Automatic Winding
The NH35 winds naturally through the motion of your wrist.
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Wearing your watch for 8+ hours daily typically keeps it fully charged.
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Full power reserve lasts about 41 hours once fully wound.
2. Manual Winding
If your watch has stopped or you haven’t worn it for a while:
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Ensure the crown is in Position 0 (fully pushed/screwed in).
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Turn the crown clockwise (away from you) about 20–30 times.
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You’ll feel slight resistance — this is normal. The movement has a slipping clutch, so overwinding won’t cause damage, but it’s best not to force it.
Crown Operation
Depending on the model, your crown will be either push-pull or screw-down:
Screw-Down Crown
Some NH35 watches (especially divers and mods) have a screw-down crown for better water resistance.
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To use it, first unscrew the crown by turning counter clockwise until it pops out gently.
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Once it’s free, it acts like a normal push-pull crown.
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When done setting or winding, press and screw it back in tightly to maintain water resistance.
Push-Pull Crown
If your crown pulls out easily without unscrewing, it’s a standard push-pull design.
Handle gently when pulling between positions.
Crown Positions
| Position | Function | Notes |
|---|---|---|
| 0 (pushed in) | Normal position — watch running, manual winding available | For daily wear and winding |
| 1 (half pulled) | Date setting | Turn clockwise to advance the date |
| 2 (fully pulled) | Time setting — movement stops (hacking) | Used for precise time setting |
Setting the Time
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Pull the crown out to Position 2 (fully extended).
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Turn the crown to move the hands.
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Avoid setting the time between 8 PM and 3 AM, as the date-change mechanism may be engaged and could be damaged.
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Once the time is set, push the crown back in to Position 0 (or screw down if your model has a screw crown).
Setting the Date
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Pull the crown to Position 1 (half pulled).
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Turn the crown clockwise to advance the date.
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To ensure correct AM/PM, set the date to the day before today, then move the hands past midnight in Position 2 to reach the correct date.
⚠️ Important: Never set the date between 8 PM and 3 AM — this may damage the calendar gears.
Water Resistance
Water resistance varies by model and build.
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Screw-down crowns generally offer better sealing (up to 100m+).
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Push-pull crowns typically resist only splashes or light rain.
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Avoid hot water, saunas, or high humidity environments — heat expands seals and reduces protection.
Maintenance & Care
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Store in a dry place, face-up when not in use.
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Avoid strong magnetic fields (phones, speakers, laptops).
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Service the movement every 3–5 years for cleaning and oiling.
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If dropped or subjected to shock, the balance or rotor may need inspection.
Troubleshooting Guide
Summary of Best Practices
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Wind manually if inactive for more than a day.
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Keep away from magnets and moisture.
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Always screw the crown back down (if applicable).
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Never set the date during the auto-change window (8PM–3AM).
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Treat it with care — it’s a precision instrument.
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