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4.
If "nogo" appears on the display during AUTO ZERO, use the coarse zero
procedure described in Section 6. If "nogo" appears during automatic calibration,
calibrate manually as described in Section 12A.
5.
Replace the two rubber plugs on the side of the instrument.
C.
Replacement of the CO/H
The CO/H
S cell should not be opened since it contains a corrosive sulfuric acid
2
electrolyte. The old cell should be returned to Bascom-Turner for proper disposal. Please use
the container furnished with the replacement cell for the return.
The tool required for replacement and calibration is a Phillips #1 screwdriver.
I.
Replacement of the CO/H
The following stepwise procedure will result in an efficient and trouble-free installation.
In carrying it out, please note carefully which cables are plugged in each connector on the board
and the orientation of each connector to avoid swapping or forcing a connector.
1.
Make sure the selector switch is in the OFF position, then remove the two screws
from the back of the case and lift the top cover exposing the main circuit board.
Remove the two rubber plugs on the side of the case. Unscrew the plastic cable
clamp near the 6 pin connector and leave it on the cable.
2.
Disconnect the 6 pin connector noting that the printing on this connector is visible
when oriented correctly.
3.
Remove the battery compartment cover and the four AA batteries. Slowly lift the
main circuit board by raising the side of the board away from the 6 pin filament
connector to expose the connectors on the underside of the main circuit board (Fig.
9). Unplug the 2-connector cables to the motor and alarm. The 2 pin connector
further from the display connects the pump motor to the main board, the one nearest
the display connects the alarm. Unplug the keyed, 3-pin connector to the CO cell
(middle of the board) and the 2 pin connector next to it (this last connects the
oxygen cell). Remove the board.
4.
Remove the four screws which hold the CO sensor to the manifold and remove the
CO sensor from the manifold. Verify that an O-ring is in position in the manifold's
well and the well is clean.
5.
Remove the plastic (mylar) gasket from the old CO cell and place it on the bottom
of the new CO sensor. Place the new CO sensor into the manifold and tighten the
four screws to hold the sensor firmly against the O-ring.
S Sensor
2
S Cell
2
32
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