First check the caliber printed on your watch’s case back. The steps below apply to Seiko Speedtimer watches using calibers 8R46 or 8R48; if your watch has another caliber, follow the matching manual instead. For an 8R46 or 8R48, set the date to the previous day, then advance the hands through midnight to today and on to the correct time. Do not adjust the date while the watch displays a time between 8 p.m. and 2 a.m.
Seiko’s instruction lookup lets you find the manual for the caliber code on your case back.
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Before you begin: confirm the caliber and stop the stopwatch
Look for the caliber code on the case back. Seiko’s procedure below is for 8R46 and 8R48; the Speedtimer name alone does not establish which setting instructions apply. Seiko’s mechanical Speedtimer lineup uses 8R-series movements, but use the manual for your specific caliber if the code on your watch is different. See Seiko’s mechanical Speedtimer lineup and caliber-specific instruction lookup.
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- Check whether your crown is a screw-lock type. If it is, turn it counterclockwise to unlock it before setting.
Set an 8R46 or 8R48 Speedtimer
- Set the date to the previous day. Pull the crown to the first click and turn it counterclockwise until the date shows yesterday. For example, if today is the 6th, set the date to the 5th.
- Stop the seconds hand at 12. Wait for the seconds hand to reach 12, then pull the crown to the second click. The seconds hand stops, allowing you to set the time.
- Advance through the date change. Move the hands forward until the date changes to today. This crossing of midnight establishes that the displayed time is in the AM period.
- Advance to the correct time. Continue moving the hands forward until they show the current time, taking care to distinguish morning from afternoon on the 12-hour dial.
- Restart the watch. Push the crown back to its normal position at a time signal. If the crown is screw-lock type, press it in and turn clockwise until it locks; do not force it.
Seiko’s 8R46/8R48 mechanical chronograph manual specifies the first click for date setting and the second click for time setting.
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Why the date must be set outside the danger window
Seiko warns: “Avoid amending the date when the watch is displaying between 8 PM and 2 AM. Doing so may cause damage.” This warning applies to the 8R46/8R48 manual. If the watch is showing a time in that interval, move the hands to a time outside it before using the first crown click to adjust the date.
Correct the calendar after a short month
The 8R46/8R48 calendar needs a manual correction at the end of February and after months with 30 days. On the morning after a 30-day month, Seiko’s manual says to use the first crown click to set the date to 1, then return the crown to normal. Make this adjustment only when the displayed time is outside the 8 p.m.–2 a.m. interval.
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If the setting steps do not match your watch
Do not force the crown or assume another Speedtimer caliber uses the same procedure. Check the case-back code and retrieve its matching manual through Seiko’s instruction lookup. If the crown or date does not operate normally, stop rather than applying extra force.
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