Chilled Mirror Cleaning & Recalibration

It is best to do the recalibration and cleaning in an indoor
environment. Stable temperatures and dew points are needed. If the unit
is outdoors or in an environment where temperature and dew point is
fluctuating during the recalibration the settling time of the unit will
take much longer.

Items needed: Fluke meter able to read 0 -- 5 V DC, distilled water,
lacquer thinner, isopropyl alcohol, cotton swabs.

1.  Remove CMH unit from the tower and take inside the GW or back to the
    duplex.

2.  Leave power disconnected from unit at this time.

3.  Turn Auto balance dial to 000 so that 0 is read in the "window" and
    0 is set to the mark below the window.

4.  Remove mirror assembly from the sensor housing assembly (white
    mushroom).

    a.  Remove retaining screw from side of housing assembly

    b.  Grab sensor (from the bottom) by the handle and pull assembly
        out, you may want to disconnect the sensor data cable. The unit
        connects through two banana connectors and slides in and out of
        assembly only one way.

5.  Once unit is removed you can begin the cleaning of the mirror. Begin
    by taking a clean cotton swab and distilled water, thoroughly wet
    mirror surface using a moistened swab. Once mirror is wet, wash with
    a gentle circular motion.

6.  Wipe the surface with a clean dry swab until dry and all loosened
    material is removed.

7.  Repeat steps 4 and 5 until the cleaning has no further effect, i.e.
    dry swab is clean after drying sequence.

8.  Repeat steps 4 & 5 using lacquer thinner.

9.  Continue lacquer thinner cleaning until it has no further effect.

10. Repeat steps 4 & 5 using Isopropyl Alcohol.

11. Continue alcohol cleaning until it has no further effect.

12. NEVER use soap or any other detergent to wash mirror.

13. Re-install mirror assembly into the sensor housing assembly. Ensure
    the banana connector line up before seating mirror assembly. Tighten
    retaining screw and ensure the grounding cable is connected also
    between the assembly cap and retaining screw.

14. Reconnect the sensor data cable to the main housing unit.

15. Apply AC power to the unit.

16. Turn the Mode Selector Switch to HEAT, and leave on for 1 minute.
    This will ensure a dry mirror after following the cleaning steps
    above. Turn mode Selector Switch to OPR position after 1 minute time
    period is up.

17. Remove AC power.

18. Connect a digital voltmeter set to read 0 -- 5 V DC to the transmit
    logic board. Connect the positive lead to the left side of R3
    (junction of R8, R3, and C2) on the transmit logic board and the
    negative lead to ground.

19. Reapply AC power.

20. THE FOLLOWING STEPS MUST BE DONE WITH A COMPLETELY DRY MIRROR. TO
    INSURE A DRY MIRROR CHECK THAT THE DEW POINT IS ABOVE THE AMBIENT
    AIR TEMPERATURE BY TOGGLING THE MONITOR SELECTOR SWITCH BETWEEN Ta
    and Td AND PUSHING THE MONITOR DISPLAY SWITCH TO READ THE VALUES.
    NEED TO KEEP Td ABOVE Td. THE FOLLOWING ADJUSTMENTS **MUST NOT** BE
    MADE WHILE HEATING THE MIRROR. YOU **MUST** MONITOR THE Td, AND HEAT
    AS NECESARRY. MAKE MEASUREMENTS AND ADJUSTMENTS **IN BETWEEN**
    HEATING CYCLES. SELECTOR SWITCH SHOULD BE IN **OPR** POSITION WHEN
    MAKING ADJUSTMENTS

21. Turn the Sd gain adjustment (R21) clockwise until the Sd LED (CR5)
    just goes on. This is the threshold level. The voltmeter should read
    approximately 4.9 Volts.

22. Adjust the Si gain adjustment (R22) Clockwise until the Si LED (CR9)
    goes on then let system stabilize then turn the Si gain adjustment
    CounterClockwise until the Si LED (CR9) just goes off.