Met One Instruments 020C Operation Manual page 7

Symptom
No wind direction
output
No change in
wind direction
output below 2-5
mph
4.2 020C Wind Direction Sensor: 6-12 Month Periodic Service (Refer to Assembly
Drawing)
A. At the crossarm assembly, disconnect the quick disconnect plug from the sensor
(leave the cable secured to the crossarm). Remove the sensor from the
crossarm assembly bushing. Leave the bushing secure in the fitting.
B. Loosen the set screw on the bottom edge of the vane hub. Support the rotating
hub of the sensor with one hand and pull the vane assembly free.
C. Visually inspect the wind vane assembly to ensure that the wind vane and
counterweight are securely attached to the wind vane rod, and that the set screw
in the top edge of the rotating hub holds the rod in place.
D. Slide the sensor cover down to expose the potentiometer assembly and signal
conditioning module.
E. Inspect the interior of the sensor for any signs of corrosion.
F. Inspect the potentiometer for loose wires, cracks, and corrosion.
G. Inspect the shaft coupler for proper position. Make sure that the marks on the
rotating hub and the column assembly are aligned, and that all special set screws
are tight.
H. Inspect the circuit board assembly for cracks and corrosion. See Section 4.6 B.
020C-9800 REV A
Probable Cause
Loss of supply
voltage
Faulty integrated
circuit amplifier
(output often will be
steady 5.0V)
Faulty potentiometer
Bad bearings
Solution
Check translator
+12V supply and
connecting cables
Replace IC amplifier
(Plug-in)
Replace
potentiometer
Replace bearings
Refer to
Figure 2-1
Section 4.8
Section 4.6
Section 4.5
Page 6