Manual for 8285 seiko mod watch movement
MIYOTA 8285
AUTOMATIC MOVEMENT USER MANUAL
(For Watches and Mod Builds Using the Miyota 8285 Automatic Movement — Day/Date)
Overview
Your watch is equipped with the Miyota 8285, a dependable Japanese automatic movement known for its reliability and smooth day/date functionality. It winds through wrist motion and can also be manually wound via the crown.
The 8285 is widely used in microbrand watches and modded builds due to its durability and simple maintenance.
Case design, crown type, and water resistance vary depending on the watch model. Review this guide before operation.
Powering the Movement
1. Automatic Winding
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Moves naturally wind the rotor inside the movement.
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Wearing the watch for 8+ hours per day typically keeps it fully powered.
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Full power reserve lasts approximately 40 hours.
2. Manual Winding
If the watch has stopped or sat unused:
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Ensure the crown is in Position 0 (fully pushed/screwed in).
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Turn the crown clockwise roughly 15–20 turns.
The 8285 has a basic winding system — wind gently, and don’t force the crown.
Crown Operation
Your watch will use either a screw-down or push-pull crown.
Screw-Down Crown
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Turn counterclockwise to release.
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After use, push in and screw down firmly to restore water resistance.
Push-Pull Crown
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Simply pull to switch positions.
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Always push fully in when finished.
Crown Positions
| Position | Function | Notes |
|---|---|---|
| 0 (pushed in) | Watch running; manual winding | Daily use position (unscrewed crown) |
| 1 (half pulled) | Day & Date setting | Turn clockwise for date; counterclockwise for day |
| 2 (fully pulled) | Time setting | Seconds hand continues running (non-hacking) |
Setting the Time
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Pull the crown to Position 2.
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Turn the crown to set the correct time.
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Push the crown back to Position 0 (and screw down if applicable).
Identify AM/PM
Since the 8285 uses a date+day mechanism:
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Rotate the hands past 12:00.
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If the date changes, you’re in AM.
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If not, you’re in PM.
Setting the Date & Day
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Pull crown to Position 1.
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Turn clockwise → changes the date.
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Turn counterclockwise → changes the day.
⚠️ Never set the date or day between 9 PM and 3 AM.
This is the danger window where the calendar gears engage and can be damaged.
Water Resistance
Water resistance depends on your case and crown.
General rules:
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Screw-down crown = generally higher water resistance.
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Push-pull crown = splash resistant, not recommended for submersion.
Avoid:
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Steam rooms, showers, hot tubs
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Water exposure with the crown open
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High-pressure water jets
Heat weakens gasket seals — keep it cool and dry.
Maintenance & Care
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Store in a dry place, preferably face-up.
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Keep away from speakers, magnetic cases, and strong electronic magnets.
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Service every 3–5 years for lubrication and accuracy.
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After impacts or drops, the rotor and balance may require inspection.
The Miyota 8285 is rugged but still a mechanical instrument — treat it with respect.
Summary of Best Practices
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Manually wind if unworn for over 24 hours.
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Avoid setting the day/date between 9 PM–3 AM.
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Keep magnets and moisture away.
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Always secure the crown (especially screw-down types).
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Follow regular servicing intervals.
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