Sensor/Pressure Equipped On Front Of The Watch; Altimeter Of Watches Equipped With A Sensor/Pressure - Casio PRT-40C Repair Manual

11-4-2 Sensor/Pressure Equipped on Front of the Watch

For the names of each parts and construction. Please refer to page 20 the exploded view of the
Watches Equipped with a Sensor/pressure (Front Sensor).
1) Open the cover/back.
2) Take out the module from the case. The module is hooked in 6 and 12 o'clock side of the case. So
unhook two hooks with precision screw driver or tweezers at first, then lift up the module from the
case.
3) Unscrew and remove two screws under the module.
4) Remove the holder and casing frame of the sensor from the case.
5) Take out the sensor/pressure from the case.
6) When the sensor/pressure is installed again, apply the silicone grease to the packing/O-ring(sensor).
7) Install the sensor/pressure.
8) Set the holder and casing frame of the sensor. And screw up two screws for the holder.
9) Set the module in the case. Be careful to hook the two hooks in the case.
10)Perform AC operation.
11)Perform sensor trimming with the Sensor/pressure trimming jig set in case only the sensor/pres-
sure is replaced with new one.
12)In the case of water-resistant watches, always make sure to perform the waterproof inspection
after the repair is completed.

12. Altimeter of Watches Equipped with a Sensor/Pressure

Altimeters consist of actual altimeters and relative altimeters.
Actual altimeters express the altitude of a certain location from sea level in the form of a direct mea-
surement using light (laser, etc.), radio waves or sound waves.
Relative altimeters express the difference in elevation between one location and another by using the
phenomenon in which air pressure decreases by 12 hPa (mb) for 100 meter increase in altitude (up to
1,000 meters above sea level).
All altimeters used in Casio
watches are relative altimeters.
They display the value that results by
converting the difference in air pres-
sure between certain locations mea-
sured with the sensor/pressure and a
reference altitude, and then adding
that difference to the reference alti-
tude.
What is important here is that since
air pressure changes by the day and
hour, even when air pressure is mea-
sured at the same location, relative al-
titude changes proportional to
changes in air pressure.
Consequently, when using the altim-
eter (relative altimeter) of a Casio
watch, it is necessary to set the refer-
ence altitude (0 meters or the altitude
value for that location) according to the
instruction manual for each use.
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