Timex M640 - Manual (Page 7)

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is broadcast to your watch along with your performance data.
Refer to the user manual for your watch for the procedure to
check the S+D Sensor’s battery level.
Replace battery
• Flip out the half-circle handle on the battery hatch (located on
the side of the S&D Sensor case) and turn it counter-clockwise
to unscrew.
• Remove the battery hatch.
• Remove old battery and insert one (1) new AA battery. Observe
the +/- markings inside the battery compartment to ensure the
new battery is properly aligned.
• Replace the battery hatch and tighten the cap by turning clock-
wise. Do not over-tighten.
Maintenance
Rinse the S+D Sensor and its strap in fresh water periodically to
avoid buildup of materials that can interfere with the measurement
of your speed and distance.
Resolving S+D Sensor Errors and Error Messages
PROBLEM
• The S+D Sensor cannot lock onto GPS satellites (ON/OFF button
never changes to flashing green).
• The GPS S+D Sensor loses signals from the satellites during use.
The watch may display a message that the GPS signal is weak.
SOLUTION
• Move to a more open outdoor area.
• Move away from metal objects.
• Replace the battery in the S+D Sensor.
NOTE: The system can maintain accuracy for short periods when
GPS signals are lost.
PROBLEM
• Watch displays FATAL GPS ERROR message.
SOLUTION
• The S+D Sensor is damaged; contact Timex Customer Service.
S+D Sensor Battery Life and Replacement
The battery in the S+D Sensor will last approximately 12 hours.
The S+D Sensor itself does not indicate the condition of its
battery, except if the battery is completely exhausted (as noted in
the section “Operating the S+D Sensor”). Instead, this information
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