12 • 35-3001A-13-XX CO
2
/CO Sample-Draw Detector
Carbon Monoxide Sensor/CO Amplifier
The carbon monoxide sensor is a plug-in sensor that plugs into the back of the CO amplifier. The sensor and
amplifier are retained in the flow block by two screws. The flow block is mounted to the middle of the main
circuit board. It is the higher of the two flow blocks mounted to the main circuit board.
Through a series of chemical and electronic reactions, the CO sensor produces a millivolt output that is
proportional to the detection range of the sample-draw detector. A red wire and a blue wire extend from the CO
amplifier and allow connection to the detector/amp terminal strip.
Zero Pot
The zero pot is located in the lower right corner of the amplifier (see Figure 4). Use a small flat blade screwdriver
to turn the zero pot’s adjustment screw and adjust the amplifier’s zero output during the start up and calibration
procedures. Turn the adjustment screw clockwise to increase the zero output and counterclockwise to decrease
the zero output.
Span Pot
The span pot is located to the left of the zero pot (see Figure 4). Use a small flat blade screwdriver to turn the
span pot’s adjustment screw and adjust the amplifier’s gas response during the calibration procedure. Turn the
adjustment screw clockwise to increase the span output and counterclockwise to decrease the span output.
Test Points
The test points are on the top edge of the amplifier (see Figure 4). The test points produce a 100 mV to 500 mV
output that corresponds to the sample-draw detector’s 4 to 20 mA output. Use the test points and a voltmeter to
measure the amplifier’s output during the start-up and calibration procedures. The black test point (CAL 2) in the
upper left corner is the negative (-) test point and the red test point (CAL 1) in the upper right corner is the
positive (+) test point.
Span Pot
Zero Pot
Test Points
100-500 mV Range
Figure 4: CO Amplifier Component Location
