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

Heater Wire

Heater Wire

 

LED OFF

LED ON

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

Heater Wire

Heater Wire

 

LED OFF

LED ON

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.

8.1.3Humidifier 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).

MR850 Technical Manual * Revision J * Issued November 2005 * Ref. 185041340 (185041713 internal)

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