Removing And Replacing; Removing And Replacing The Optical Units - Vaisala PWD22 User Manual

User's Guide _______________________________________________________________________

Removing and Replacing

CAUTION
NOTE
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1. Give the following command:
CAL calibrator signal value
For example:
CAL
The calibrator signal value is printed on the labels of the glass
plates. Typically the signal is close to 500 Hz. PWD22
calculates a new scaling factor and stores it in the non-volatile
memory (EEPROM).
2. Type CHEC to verify that the new scaling factor is in use. The
displayed signal value should be equal to the calibrator signal
value. If the difference between the new scaling factor and the
factory calibrated one is more than 20 %, the CAL command
will be ignored. Check PWD22 and the calibrator for hardware
or mechanical errors. Also consult Vaisala
If the optical units PWC22 or PWT11 have been replaced, the
new scaling factor might change more than 20 % from the
original scaling factor, value and the CAL command is ignored.
In this case use the FCAL command (factory calibration)
instead of CAL during the calibration procedure.
This section describes in detail how to remove and replace the optical
units PWT11 Transmitter and PWC22 Controller/Receiver. Removing
the units comes into question, when there is reason to suspect that
malfunction of PWD22 is caused by faults in the optical units or the
rain detector.
Removing and Replacing the
Optical Units
Servicing the equipment must be performed by qualified personnel.
After replacing the optical units you need factory calibration. (See
section Calibration Procedure on page 93).
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