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Ref. 185040646 MR730/720/700/480 Technical Manual ¯ Revision F ¯ Issued March 2001
1 Plug in the 41 °C calibration probe.
2 Gain access to the adjustment potentiometers VR4 and VR5, by removing the control board from the humidifier
front panel.
3 With the Chamber Temp button held down turn on the power switch. Display should show -1-
4 Using the Chamber Temp button step through to number -4-
5 Starting with a vertical bar display adjust VR4 so the display changes to an all 8 display. If VR4 is rotated too
far the display becomes all horizontal bars (||.||.||. thru 8.8.8. to ===). The correct point is where all the
segments of the all 8 display are of equal brightness.
6 Using the Chamber Temp button step to number -5-
7 Remove the 41 °C calibration probe.
8 Adjust VR5 for a display reading of zero. (0)
(This value may drift over time. A deviation of up to ± 2.0 will not affect circuit performance.)
9 Calibration is complete; do performance check (§ 6.0)