Campbell Scientific 380, 385, 380M, 385M Met One Rain Gages - Manual (Page 18)

Met One Rain Gage Models 380 and 385
6. Troubleshooting
6.1 Precipitation
Symptom: No precipitation
1. Check that the sensor is wired to the Pulse Channel specified by the Pulse
Count instruction.
2. Verify that the Configuration Code (Switch Closure), and Multiplier and
Offset parameters for the Pulse Count instruction are correct for the
datalogger type.
3. Disconnect the sensor from the datalogger and use an ohm meter to do a
continuity check of the switch. The resistance measured at the terminal
block on the inside of the bucket between the black and white leads
should vary from infinite (switch open) when the bucket is tipped, to less
than an ohm when the bucket is balanced.
7. Maintenance and Calibration
During each site visit, check for and remove any debris, insects, sediment, etc.
from the collection funnel, debris screens, or tipping bucket assembly. Verify
the tipping bucket assembly moves freely, and that the datalogger records 0.01
in for each bucket tip.
7.1 Customer Calibration
The sensor is factory calibrated; recalibration is not required unless damage
has occurred or the adjustment screws have loosened. Nevertheless, the
following calibration check is recommended once every 12 months:
a. Remove the housing assembly from the base by loosening the three
screws and lifting upward on the housing.
b. Check bubble level to verify sensor is level.
c. Pour water through the inner funnel to wet the two bucket surfaces.
Using a graduated cylinder, slowly pour the appropriate amount of
water (refer to Table 7-1) through the inner funnel to the tipping
bucket, which should tip once. Repeat for the other bucket. If both
buckets tip when filled with the appropriate amount of water (refer to
Table 7-1), the sensor is properly calibrated and no additional
adjustment is needed. If either bucket fails to tip, recalibrate as
follows:
1. Release the lock nuts on the cup adjustments.
2. Move the adjustment screws down to a position that would place the
bucket far out of calibration.
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