35-3001A-04-02 Carbon Monoxide Sample-Draw Detector • 11
CO Amplifier
The amplifier converts the electrical output from the detector to a 4 to 20 mA signal that
corresponds to the detection range and transmits the signal to a gas monitoring controller. The
amplifier includes the controller terminal strip, detector terminal strip, zero pot, span pot, and test
points (see Figure 4).
Figure 4: CO Amplifier Component Location
Controller Terminal Strip
The controller terminal strip is a two position plug-in style terminal strip located at the top edge of
the amplifier. The controller terminal strip is factory wired to the detector/amp terminal strip on the
main board.
Detector Terminal Strip
The detector terminal strip is a four position plug-in style terminal strip located below the controller
terminal strip. Two of the positions are for use with an oxygen detector and are not used in the CO
transmitter. The CO detector is factory wired to the two detector positions labeled “TOXIC”.
Zero Pot
The zero pot is located in the upper left 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 (CO-free) output
during the start-up and calibration procedure. 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 right 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 response output during the start
up and calibration procedure. Turn the adjustment screw clockwise to increase the response output
and counterclockwise to decrease the response output.
CAUTION:
The amplifier includes an additional pot. It is factory-set. Do not adjust it.
Test Points
The test points are on the left side of the amplifier (see Figure 4). The test points produce a 100 mV
to 500 mV output that corresponds to the transmitter’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 lower left corner is the negative (-) test point and the red test point below the
zero pot is the positive (+) test point.
S
ZERO
SPAN
SIG/PWR
TOXIC OXY
- Test Point (Black)
+ Test Point (Red)
Zero Pot
Detector Terminal Strip
Controller Terminal Strip
Span Pot
Factory Adjust Pot
