User`s guide

Chapter 5 ___________________________________________________________ Troubleshooting
VAISALA______________________________________________________________________ 197
Present Weather Sensor
For more information, refer to FD12P User's Guide.
WARNING
The equipment contains dangerous voltage of 230 VAC.
Table 39 Some Common Problems with FD12P and Their
Remedies
Problem Probable Cause Remedy
The visibility value is
continuously too good.
The lenses may be excessively
contaminated
Clean the lenses.
One of the hoods has been filled with
snow, leaves or other things.
Clean the hoods.
There is condensation on the lens
surfaces. This is a sign of heating
failure.
See FD12P User's Guide.
Electrical fault in transmitter or
receiver.
Visibility is constantly
too low.
Usually there is something disturbing
the sample volume. Check the
condition of the hoods.
If the hoods are slightly twisted, try to
align them as much as possible.
Contact Vaisala HelpDesk.
Try to find better direction for the
receiver/transmitter optics.
Electrical fault. See FD12P User's Guide.
FD12P reports
precipitation when there
is none.
Flashing lights may cause FD12P to
detect peaks in the optical signal.
Check that there are no flashing
lights close to FD12P.
Tree branches or any other moving
objects in the sample volume may
cause sudden changes in the scatter
signal.
Check that there are no foreign
objects in the sample volume.
If false detection has occurred in
temperature above 0 °C, DRD12
does not function correctly.
Clean the DRD12 sensing surfaces
thoroughly.
Check the DRD12 operation.
FD12P reports frozen
precipitation during rain.
The ratio of optical intensity
measurement to DRD12
measurement is too high.
Check the optical calibration and
DRD12 operation.