MAINTENANCE FOR AREARAE STEEL
7-8
Special Bias Voltage for Toxic Sensors
The NO and NH
3
toxic sensors require a special 300 mV bias
voltage to operate. Only the first toxic sensor socket provides
such a special bias voltage. Therefore, NO or NH
3
toxic
sensors must be installed into the first toxic sensor socket
(Tox1) in AreaRAE-Gamma.
In addition, there is a dip switch or pin jumper located on the
analog PCB next to the PID sensor. When an NO or NH
3
toxic
sensor is plugged into the first toxic sensor socket, it is
necessary to switch the jumper to the right to enable the bias
voltage. During power on sequence, the microprocessor will
check the sensor ID and the bias voltage. If the NO or NH
3
sensor is plugged into the wrong toxic sensor socket or he
jumper is not switched on, an error message will be displayed.
