Seiko Cal. 8T63, 8T68 Chronograph Watch User Manual

Table of Contents

This document provides instructions for Seiko Cal. 8T63 and 8T68 chronograph watches. Key sections include:

• Screw-down Crown
• Setting the Time
• Setting the Date
• Chronograph Operation
• Tachymeter Function
• Telemeter Function
• Battery Replacement
• Specifications

For detailed care instructions, refer to the World Guarantee and Instruction Booklet.

1. Screw-down Crown with Lock

Some Seiko models feature a screw-down crown mechanism to enhance water resistance and prevent accidental operation.

To Unlock: Rotate the crown counter-clockwise until it disengages.

To Lock: After use, gently push the crown in and rotate it clockwise until it locks securely. Ensure it engages with the thread properly to avoid damage.

Diagram Description: A visual shows the crown in a locked position (screwed in) and an unlocked position (pulled out slightly).

2. Setting the Time and Date

Setting the Time:

1. Pull the crown out to the second click when the small second hand is at the 12 o'clock position.
2. Rotate the crown to set the hour and minute hands.
3. The 24-hour hand moves in sync with the hour hand.
4. Ensure the AM/PM setting is correct using the 24-hour hand.
5. Advance the minute hand 4-5 minutes past the desired time, then return it to the exact time.
6. Push the crown back to its normal position simultaneously with a time signal.

Diagram Description: Shows the watch face with hour, minute, second, 24-hour hands, and the crown pulled out to the second click.

Setting the Date:

1. Ensure the time is set correctly before setting the date.
2. Pull the crown out to the first click.
3. Rotate the crown clockwise to set the desired date.
4. Push the crown back to its normal position.

Important Note: Do not set the date between 9:00 PM and 3:00 AM to avoid potential date change errors. Adjust the date manually for months with fewer than 31 days (April, June, September, November) and for February.

Diagram Description: Shows the watch face and the crown pulled out to the first click, with the date changing.

3. Chronograph Operation

The chronograph measures elapsed time up to 60 minutes in 1/5-second increments. It stops after 60 minutes.

Resetting Chronograph Hands to Zero:

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

Diagram Description: Shows the chronograph sub-dials (minute, 1/5 second, second hands) and buttons A and B.

Standard Measurement:

• Press A to start.
• Press A to stop.
• Press B to reset.

Lap Time Measurement (Split Time):

• Press A to start.
• Press A to stop and record lap time.
• Press A again to resume timing.
• Press B to reset all chronograph hands to zero.

Diagram Description: Illustrates the sequence of button presses for standard and lap time measurements.

Note: Button resistance may feel different from standard watches due to the chronograph mechanism. Pressing button B while timing will reset the chronograph; use with care.

4. Tachymeter Function

The tachymeter scale allows measurement of average speed or productivity.

Measuring Average Speed:

1. Use the chronograph to measure the time taken to travel 1 km or 1 mile.
2. Observe the chronograph second hand's position on the tachymeter scale. This indicates the average speed in units per hour (e.g., km/h or mph).

Example 1: If it takes 40 seconds to travel 1 km, the second hand points to "90" on the tachymeter scale, indicating 90 km/h.

Example 2: If it takes 20 seconds to travel 2 km, the second hand points to "90". Speed = 90 x 2 = 180 km/h. If it takes 20 seconds to travel 0.5 km, speed = 90 x 0.5 = 45 km/h.

Note: The tachymeter is accurate for measurements under 60 seconds.

Diagram Description: Shows a watch face with the tachymeter scale and the chronograph second hand indicating a speed value.

Measuring Hourly Productivity:

1. Use the chronograph to time how long it takes to complete one operation.
2. The chronograph second hand's position on the tachymeter scale indicates the number of operations completed per hour.

Example 1: If one operation takes 20 seconds, the second hand points to "180" on the tachymeter scale, indicating 180 operations per hour.

Example 2: If 15 operations are completed in 20 seconds, the calculation is: "180" (tachymeter reading) x 15 (operations) = 2700 operations per hour.

Diagram Description: Shows a watch face with the tachymeter scale and the chronograph second hand indicating a productivity value.

5. Telemeter Function

The telemeter scale estimates distance to events involving both light and sound (e.g., lightning).

How to Use:

1. Press button A to start the chronograph when you see the light (e.g., lightning flash).
2. Press button A again to stop the chronograph when you hear the sound (e.g., thunder).
3. Read the position of the chronograph second hand on the telemeter scale to estimate the distance.

Diagram Description: Illustrates the process: starting the chronograph at the sight of light, stopping it at the sound, and reading the telemeter scale.

Note: The telemeter scale is based on the speed of sound (approximately 0.33 km/sec or 1 km in 3 seconds). This provides an approximate distance and should not be relied upon for critical safety decisions. Sound speed varies with temperature.

Attention: The telemeter provides only an approximate distance. Do not use it for critical safety measures like avoiding lightning strikes. Sound speed varies with atmospheric temperature.

6. Button Lock Function

For models with button lock, this feature prevents accidental chronograph activation.

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

To Lock Buttons A or B: Rotate the button clockwise until it clicks securely. The button cannot be pressed.

Diagram Description: Shows buttons A and B with arrows indicating the direction to lock and unlock.

7. Battery Replacement

The watch is powered by a miniature battery, typically lasting about 3 years. The initial battery may have a shorter life as it's used for testing functions.

Battery Indicator: When the battery is low, the small second hand will move in 2-second intervals instead of the usual 1-second intervals. Replace the battery promptly.

Recommendation: For battery replacement, it is recommended to visit an authorized Seiko dealer and use a Seiko SR936SW battery.

Note: If the chronograph is used for more than one hour per day, battery life may be reduced. After replacing the battery, reset the time and calendar.

Diagram Description: Shows the small second hand moving in 2-second intervals.

8. Specifications

• Quartz Crystal Oscillator Frequency: 32,768 Hz (cycles per second)
• Accuracy (Monthly Rate): ±15 seconds per month at normal temperatures (5°C to 35°C / 41°F to 95°F)
• Operating Temperature Range: -10°C to 60°C / 14°F to 140°F
• Drive System: Stepping motor, 2 pieces
• Indicator System:
  • Time/Calendar: 24-hour, hour, minute, and small second hands. Date displayed numerically.
  • Chronograph: Minute and 1/5-second hands. Maximum measurement up to 60 minutes.
• Battery: Seiko SR936SW, 1 piece
• Integrated Circuit: C-MOS-IC, 1 piece

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

9. Precautions and Attention

Attention:

• Do not remove the battery from the watch.
• If you must remove the battery, keep it out of reach of children. Seek immediate medical attention if a child swallows it.

Precaution:

• Never short-circuit the battery terminals, expose it to heat, or attempt to disassemble it. Do not expose it to fire. The battery may explode, become very hot, or ignite.
• Do not recharge the battery. Doing so may cause it to leak, rupture, or explode.