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MR850 Technical Manual * Revision J * Issued November 2005 * Ref. 185041340 (185041713 internal)
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1. Hold down the power button, then apply mains power to the humidifier. This action places
the humidifier into service mode.
2. Select service mode number 1 (Calibration Probe #1 Check) by pushing the mute button
when '-1-' is displayed.
3. Insert the calibration probe with the GREY collet into the temperature / flow probe socket of
the humidifier.
4. Allow the display to stabilize for a few seconds, and check the number shown on the
humidifier display. The table below shows the numbers displayed by the humidifier in this
mode:
TEST PASS FAIL (LOW) FAIL (HIGH)
Airway Temperature 100 101 102
Chamber Temperature 100 104 108
Flow Temperature 100 110 120
Calibration Resistor 100 140 180
Overheat Heater Wire
LED OFF
Heater Wire
LED ON
Heater Wire
LED ON
If the humidifier displays any other value than '100' or if the heater wire indicator is on, check
that you have the correct calibration probe plugged in, otherwise the MR850 PCBs are faulty
and they will need to be serviced or replaced (refer 7.2.3).
5. Press the power button (this causes the Calibration Probe #2 Check to be executed).
6. Insert the calibration probe with a BLUE collet into the temperature / flow probe socket of the
humidifier.
7. Allow the displayed value to stabilize for a few seconds. Check the humidifier display. The
table below shows the numbers displayed by the humidifier in this mode:
TEST PASS FAIL (LOW) FAIL (HIGH)
Airway Temperature 200 201 202
Chamber Temperature 200 204 208
Flow Temperature 200 210 220
Calibration Resistor 200 240 280
Overheat Heater Wire
LED OFF
Heater Wire
LED ON
Heater Wire
LED ON
If the humidifier displays any other value than '200' or if the heater wire indicator is on, check
that you have the correct calibration probe plugged in, otherwise the MR850 PCBs are faulty
and they will need to be serviced or replaced (refer 7.2.3).
8. Remove the calibration probe, and press the mute button to exit service mode.
8.1.3 Humidifier Display Test
This test is used to determine whether the humidifier's display is working correctly.
1. Enter the service menu (refer section 8.1.1).
2. Select service mode number 6 (Display test) by pushing the mute button when '-6-' is
displayed.
3. Check that all of the display LEDs and indicators are turned on.
4. Push the mode button to change to a display cycle test. Check that all the LEDs and
indicators light in sequence, and that there is only ever one LED on at a time.
5. Push the Mute button to exit back to the service menu.
If the humidifier does not pass the display test, then it is recommended that the humidifier PCBs
are either replaced or sent for servicing (refer 7.2.3).