Seiko Cal. 8T63, 8T68 Chronograph Watch Manual

Table of Contents

• Screw-down Crown: Page 113

• Setting the Time: Page 114

• Setting the Date: Page 115

• Stopwatch: Page 116

• Button Lock Function: Page 118

• Tachymeter: Page 119

• Telemeter: Page 121

• Battery Replacement: Page 123

• Specifications: Page 125

For proper care of your watch, please refer to the section 'How to Preserve the Quality of Your Watch' in the enclosed World Warranty and Instruction Booklet.

Screw-down Crown with Lock

Some Seiko models feature a screw-down crown mechanism for enhanced security and water resistance. This lock prevents accidental operation.

How to Unlock: To unlock the crown, turn it counter-clockwise. It will then be ready for use.

How to Lock: After completing operations, turn the crown clockwise gently until it stops. Ensure it is securely locked.

Caution: When locking the crown, turn it carefully to ensure it engages the thread properly. Forcing the crown may damage the threading.

Diagram Description: The watch face diagrams for Cal. 8T63 and Cal. 8T68 show the arrangement of hour, minute, 1/5 second, and 24-hour hands, the date window, and the crown (⚙️). The crown positions are indicated as 'a' (initial position), 'b' (1st click), and 'c' (2nd click).

If your watch is equipped with a screw-down crown, please follow the instructions in this section.

Setting the Time ⏰

Diagram Description: A watch face illustration shows the hour, minute, 24-hour, and small second hands, along with the crown (⚙️).

1. Pull the crown (⚙️) out to the second click when the small second hand is at the 12 o'clock position.
2. Turn the crown to set the current time.
3. Return the crown to its normal position simultaneously with a time signal (e.g., a radio time signal) for accurate setting.

Notes:

• If the crown is pulled to the second click while the stopwatch is running, the stopwatch will continue to measure time.
• The 24-hour hand moves in conjunction with the hour hand.
• The date changes at midnight. When setting the hour hand, use the 24-hour hand to ensure the correct AM/PM setting.
• When setting the minute hand, it is recommended to advance it 4-5 minutes past the desired time and then return it to the exact minute.

Setting the Date ?

Note: It is essential to set the time accurately before setting the date.

Diagram Description: A watch face illustration shows the hands and the crown (⚙️).

1. Pull the crown (⚙️) out to the first click.
2. Turn the crown clockwise until the desired date appears.
3. Return the crown to its normal position.

Notes:

• Date setting should always be performed after the time has been set.
• Manually adjust the date at the end of months that have fewer than 31 days (February, April, June, September, November).
• Avoid setting the date between 9:00 PM and 3:00 AM. Performing this action during these hours may result in an error in the date change.

Stopwatch ⏱️

The stopwatch can measure elapsed time for up to 60 minutes, with a 1/5 second increment. It will automatically stop after 60 minutes of operation.

Diagram Description: A watch face illustration shows the minute and 1/5 second hands of the stopwatch.

How to Reset Stopwatch Readings:

• If the stopwatch hands are moving: Press button A to stop the stopwatch, then press button B to reset the hands to zero.
• If the stopwatch hands are stopped: Press button B to reset the hands to zero.

Standard Measurement:

• Button A: START / STOP ▶️⏸️
• Button B: RESET ?

Lap Time Measurement:

• START ▶️ (Press A)
• STOP ⏸️ (Press A)
• RESET ? (Press B)
• START ▶️ (Press A)
• STOP ⏸️ (Press A)
• RESET ? (Press B)

Note: Before using the stopwatch, ensure all hands are set to the '0' position.

Important Notes:

• You may notice that the buttons require a firmer press than on standard watches. This is due to the specialized mechanism required for stopwatch functions and is not a defect.
• Pressing button B while the stopwatch is measuring time will reset the stopwatch. Be careful not to press this button accidentally.

Button Lock Function ??

(For models with button lock function)

Locking Buttons A and B:

Diagram Description: A watch face illustration shows buttons A and B. Arrows indicate that rotating the buttons locks or unlocks them.

To Unlock: Rotate button A or B counter-clockwise until it clicks. The button can now be pressed.

To Lock: To prevent accidental pressing, rotate the button clockwise until it clicks. The button can no longer be pressed.

Tachymeter ?️

(For models with a tachymeter scale)

Used to measure the average speed (km/h or mph) of a vehicle.

How to Measure Average Speed:

1. Use the stopwatch to measure the time taken to travel 1 km or 1 mile.
2. When the stopwatch is stopped, the stopwatch second hand indicates the average speed per hour on the tachymeter scale.

Example 1: If you cover 1 km in 40 seconds, the stopwatch second hand points to '90' on the tachymeter scale. Your speed is calculated as: '90' (Tachymeter Reading) x 1 (km/mile) = 90 km/h or mph.

Note: The tachymeter scale is only usable if the time taken to cover the measured distance is less than 60 seconds.

Example 2: If you cover 2 km (or 0.5 km) in 40 seconds, and the stopwatch second hand points to '90' on the tachymeter scale, your speed is:

• For 2 km: '90' (Tachymeter Reading) x 2 (km/miles) = 180 km/h or mph.
• For 0.5 km: '90' (Tachymeter Reading) x 0.5 (km/miles) = 45 km/h or mph.

Measuring Hourly Productivity:

Diagram Description: A watch face illustration shows the stopwatch second hand pointing to a value on the tachymeter scale.

1. Use the stopwatch to measure the time required to complete one operation.
2. The number on the tachymeter scale indicated by the stopwatch second hand shows the average number of operations performed per hour.

Example 1: If one operation takes 20 seconds, the stopwatch second hand points to '180' on the tachymeter scale. Productivity = '180' (Tachymeter Reading) x 1 (operation) = 180 operations/hour.

Example 2: If 15 operations are completed in 20 seconds, Productivity = '180' (Tachymeter Reading) x 15 (operations) = 2700 operations/hour.

Telemeter ⚡️

(For models with a telemeter scale on the dial)

The telemeter system provides an approximate indication of the distance from the source of light and sound.

This system indicates the distance from your location to an object emitting light and sound. For instance, it can measure the distance to a lightning strike by timing the interval between seeing the flash and hearing the thunder.

Light travels almost instantaneously, while sound travels at approximately 0.33 km/sec. The distance can be calculated based on this time difference.

The telemeter scale is calibrated assuming sound travels at 1 km in 3 seconds (approximately 0.33 km/sec). This calculation is based on a temperature of 20°C.

⚠️ WARNING: The telemeter system offers only an approximate distance to a lightning strike and should not be relied upon as the sole method for avoiding lightning hazards. Sound speed can vary depending on atmospheric temperature.

How to Use the Telemeter:

Diagram Description: Watch face illustration showing stopwatch operation for telemeter measurement.

Before use, ensure the stopwatch readings are reset.

1. Press button A ▶️ to start the stopwatch as soon as you see the light (e.g., lightning flash).
2. When you hear the sound (e.g., thunder), press button A ⏸️ to stop the stopwatch.
3. Read the measurement on the telemeter scale indicated by the stopwatch second hand.

Note: The stopwatch second hand moves in 1-second increments and may not precisely align with the telemeter scale marks. The telemeter scale is accurate for measurements taken within 60 seconds.

Battery Replacement ?

Battery Life: The miniature battery powering your watch is designed to last approximately 3 years. However, the initial battery installed at the factory is for testing functions and may have a shorter lifespan.

Recommendation: When the battery charge is low, replace it as soon as possible to prevent any malfunction. It is recommended to have the battery replaced by an authorized SEIKO dealer using a SEIKO SR936SW battery.

Note: Battery life may be reduced if the stopwatch function is used for more than one hour per day.

After replacing the battery, please set the time and calendar.

Battery Charge Indicator: When the battery charge is low, the small second hand will move in 2-second intervals instead of the usual 1-second intervals. In this case, replace the battery immediately.

Note: The accuracy of timekeeping remains unaffected even when the small second hand moves in 2-second intervals.

Specifications

Note: Specifications are subject to change for product improvement without prior notice.