BT CGA-411 Operation Manual page 36

Note: Do not press down in the center of the corrosive warning label on the CO sensor
as this may damage the electrical connection to the sensor.
Fig. 9. Intake manifold assembly and connectors inside a detector.
6. Reconnect all connectors on the bottom of the board (see Fig. 9). Make sure each
connector has the proper orientation. All 2-pin connectors are keyed, but they can
still be forced contrary to their proper orientation. The 3-pin CO connector is also
keyed (4-pin connector with one position blocked).
Return the main circuit board into place verifying that the connector leads are not
crimped or strained. Reconnect the cable to the 6 pin connector on top of the board
and secure the cable clamp to the manifold with the screw.
7. Position the top cover on the instrument, move the top gently until the selector
switch post falls into place in the slotted switch on the board, replace the two
Phillips-head screws in the back of the case, and replace the batteries, the battery
compartment cover, and the two rubber plugs on the side of the detector.
8. Allow ten minutes for the new CO cell to stabilize. Place the front panel switch at
the PPM CO display position and verify that the reading is close to zero (or reading
of less than 10 on the display). If it is not, allow further time for settling. Then
switch to AUTO ZERO, allow the instrument to zero, and calibrate the sensor
automatically (block intake after "End" and introduce calibration gas after "go" -
see Section 10).
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