When "XXX" is shown in sensor position on the display, it
indicates a missing or defective sensor. If it is a LEL sensor,
the sensor may need to be zeroed using the procedure in
Section 9.2 "LEL FAIL" Message.
When this message comes up after start-up, you can reset the
zero base of the LEL sensor as follows:
Turn on the instrument.
SENSOR NOT RECOGNIZED ("XXX"
"LEL FAIL" MESSAGE
"PLEASE WAIT" and starts to count down from 30,
depress and hold the MODE button for about 5 seconds,
until display reads "SEL LEL GAS TYPE".
Open the instrument by removing the 4 screws from the
rear cover of the case. Do not unplug the wires from the
rear cover to the sensor board. Observe the
potentiometer (trimpot) for the LEL zero. It is located
beside the pump and is the only potentiometer (trimpot)
in the instrument.
Set digital voltmeter to the DC voltage range, black lead
to test point 12 (analog ground) and the red lead to test
point 10. These test points are on the same sensor
board as the pump, trimpot and sensors.
Adjust the potentiometer (trimpot) for a reading of 0.500
volts (+/- 0.005 volts).
Exit supervisory mode.