MAINTENANCE
7-5
4. Refer to Figure 7.1, carefully unscrew four No.2 screws
that hold down the gas piping cover to the PCB and
sensors. Remove the gas piping plate.
5. Refer to Figure 7.1, identify the location of a specific
sensor and remove the sensor by gently pulling the
sensor upward.
6. Plug a new sensor into the empty sensor socket. Make
sure that black line on the sensor label is lined up with
the white marker on the PCB and the sensor pins are
aligned with the socket before pushing down the sensor.
7. Replace the gas piping cover and tighten the four screws
to hold down the sensors. Replace the battery pack and
the monitor cover.
8. Turn on the power of the VRAE. The microprocessor
will automatically recognize the sensors installed and
configure the monitor accordingly.
Special Bias Voltage for Toxi c Sensor:
The NO and NH
3
toxic sensors require a special 300 mV
bias voltage to operate. There is a dip switch located on the
PCB next to the sensors. When NO or NH
3
toxic sensor is
plugged into the toxic sensor socket, it is necessary to turn
the dip switch for the corresponding sensor to “ON”
position to enable the bias voltage. It is very important to
set the bias switch to the correct position when installing the
toxic sensors.
