SEIKO Caliber 6R20/6R21/6R24/6R27 Mechanical Watch User Manual

Characteristics of Mechanical Watches

The power source for these mechanical watches is the mainspring.

If the watch has stopped, manually wind the crown approximately 20 times to wind the mainspring and start the watch.

Unlike quartz watches, where timekeeping accuracy is measured monthly or yearly, the accuracy of mechanical watches is indicated by a daily rate (seconds gained or lost per day).

The accuracy of mechanical watches under normal use varies depending on usage conditions, such as the time worn on the wrist, ambient temperature, wrist movement, and the degree of mainspring winding.

Exposure to strong magnetic fields can temporarily cause the watch to run faster or slower. Some parts may become magnetized. In such cases, demagnetization is necessary. Please consult the store where the watch was purchased.

Parts Identification

Caliber 6R20/6R21/6R24

Caliber 6R27

Crown Operation

Check the type of your watch crown.

Some watches feature a screw-lock crown for enhanced security.

Usage

These watches are equipped with both automatic and manual winding functions.

• When worn on the wrist, the mainspring is automatically wound by movement.
• If the watch has stopped, it is recommended to wind it manually by turning the crown.

How to Wind Manually

1. Slowly rotate the crown clockwise (towards the 12 o'clock position).
   • Turning the crown counter-clockwise (towards the 6 o'clock position) does not wind the mainspring.
2. Continue winding until the power reserve indicator shows maximum. The second hand will begin to move.
3. Set the time, day of the week, and date before wearing the watch.

Notes:

• Refer to "How to Read the Power Reserve Indicator" on page 146 to check the mainspring's winding status.
• There is no need to continue winding the crown once the mainspring is fully wound. However, the crown may continue to rotate without damaging the watch mechanism.
• When fully wound, the watch will operate continuously for approximately 45 hours.
• Using a watch that is not fully wound may lead to accelerated or slowed timekeeping. To avoid this, wear the watch for at least 10 hours per day. If not worn, wind it daily at the same time.
• If the watch has stopped and the mainspring is unwound, winding the mainspring may not start the second hand immediately. This is due to the initial low torque of the mainspring. Gently shaking the watch from side to side can help start it faster.

Setting Time, Day of the Week, and Date (For Caliber 6R20/6R21/6R24/6R27)

Before setting the day of the week, date, and time, ensure the watch is running.

Note: Caliber 6R27 only displays the date.

The watch is equipped with a day and date function, designed to change every 24 hours. The date typically changes around 12 AM, and the day of the week around 2 AM. If the AM/PM function is set incorrectly, the date may change at 12 PM and the day of the week at 2 PM.

1. Pull the crown out to the first click. (The second hand will continue to move, and the watch's accuracy will not be affected).
2. Set the Day of the Week by rotating the crown clockwise.
   • For Caliber 6R24:
     • Do not set the day indicator between two days.
     • If you turn the crown when the indicator points to Saturday, the day indicator may move back to Sunday.
     • If the indicator skips past Saturday to Monday when set too quickly, slowly turn the crown for re-setting.
3. Set the Date by rotating the crown counter-clockwise. Rotate until the previous day's date appears.

   Example: If today is the 6th of the month, set the date to "5" by rotating the crown counter-clockwise.

   • For Caliber 6R24: If the date indicator is at 31, turning the crown will reset it to 1.

Setting Time and Date (Continued)

4. Pull the crown out to the second click when the second hand is at the 12 o'clock position. (The second hand will stop). Rotate the crown until the date changes to the next day. Set the current time (AM/PM). Continue moving the hands to set the current time.
5. Return the crown to the initial position simultaneously with a time signal.

Date Correction at the Beginning of the Month

Manual date correction is required at the end of each month that has fewer than 31 days.

Example: Setting the date on the first day of a month following a 30-day month.

1. The watch shows "31" instead of "1". Pull the crown out to the first click.
2. Turn the crown to set the date to "1", then return the crown to the initial position.

How to Read the Power Reserve Indicator

The power reserve indicator informs you about the winding status of the mainspring.

Before removing the watch, check the position of the power reserve indicator to ensure it has sufficient power to continue running when you are not wearing it. If necessary, wind the mainspring. (To prevent the watch from stopping, wind the mainspring with a reserve that will allow it to run uninterruptedly.)

When the mainspring is fully wound, the crown can be rotated forward without damaging the mainspring. The watch's mainspring is equipped with a limiting mechanism to prevent over-winding.

The position of the "power reserve indicator" may vary depending on the model.

Care for Your Watch

Leather Strap

• Gently blot moisture from the strap using a soft dry cloth.
• Do not rub the leather strap, as this may cause damage or loss of color.

Metal Bracelet

• To maintain the cleanliness of the bracelet, use a soft toothbrush with clean or soapy water. Be careful not to allow water to get onto the watch case.

PRECAUTIONS WHEN WEARING YOUR WATCH

• Be cautious when holding an infant or small child while wearing the watch, as the child may be injured, or an allergic reaction may occur from direct contact with the watch.
• Avoid impacts, drops, or scratches on hard surfaces, as well as strenuous sports activities that may cause temporary malfunctions in your watch.
• There is a possibility of injury when wearing the watch on your wrist, especially if you fall or collide with other people or objects.

Where to Store Your Watch

• Avoid storing the watch at temperatures below 5°C or above 35°C.
• Do not leave the watch in places exposed to strong magnetic fields (e.g., near televisions, loudspeakers, or magnetic bracelets) or static electricity.
• Do not leave the watch in places with strong vibration.
• Do not leave the watch in dusty places.
• Do not expose the watch to chemical substances or gases. (E.g.: Organic solvents such as gasoline and thinner, nail polish, cosmetic sprays, detergents, glue, mercury, and iodine-based antiseptic solutions.)
• Avoid direct contact with hot water.

Periodic Checks

These watches are precise instruments with many moving parts lubricated with special oil. Insufficient lubrication or wear on parts may cause the watch to show incorrect time or stop. Therefore, they require periodic checks.

Warranty and Repair Advice

• For repairs or checks, please contact the store where the watch was purchased or a SEIKO SERVICE CENTER.
• Before the warranty expires, please present the warranty certificate when contacting the SERVICE CENTER.
• Warranty conditions are detailed in the warranty certificate. Please read it carefully and keep it.

Troubleshooting

* For any other problems, please consult the store where the watch was purchased.

Accuracy of Mechanical Watches

The accuracy of mechanical watches is indicated by a daily rate, approximately measured over a week.

The accuracy of mechanical watches may deviate from the specified range due to slowing or acceleration caused by usage conditions, such as the duration the watch is worn on the wrist, wrist movements, and the degree of mainspring winding.

The main components in mechanical watches are made of metals that expand or contract depending on temperature. This affects the watch's accuracy. Mechanical watches may slow down at high temperatures and speed up at low temperatures.

To improve accuracy, it is important to regularly supply energy to the balance wheel, which controls the escapement mechanism. The driving force of the mainspring, which powers the mechanical watch, is not uniform when the spring is fully wound versus partially wound. The less the spring is wound, the less its driving force.

Relatively consistent accuracy can be achieved by frequent wear on the wrist for automatic watches, and by daily full winding of the mainspring at the same time for manual winding watches.

Exposure to strong external magnetic fields can temporarily cause mechanical watches to run slower or faster. Parts of the watch may become magnetized depending on the strength of the magnetic field. In this situation, consult the store where the watch was purchased, as the watch may require repair, including demagnetization.

Specifications

* The accuracy stated above is factory set.

** According to the characteristics of mechanical watches, actual accuracy may fall outside the range indicated above, depending on usage conditions such as wear time, temperature, wrist movement, and mainspring winding status.