Description • 13
Test Points
The test points are on the left side of the amplifier (see Figure 3). 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 in the upper left corner is the negative (-) test
point and the red test point to the left of the zero and span pots is the positive (+) test point.
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.
Figure 4: CO Amplifier Component Location
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.
Zero Pot
Span Pot
Test Points
100-500 mV Range
