GE PM880 User Manual page 172

Chapter 8. Maintenance and Troubleshooting
Table 6: Troubleshooting Guide for Common Problems (cont.)
Possible Cause
Symptom: Accuracy of moisture sensor is questioned. (cont.)
Sensor is corroded
(refer to Application of the
Hygrometer).
Sensor temperature is
greater than 70°C (158°F).
Stream particles causing
abrasion.
Symptom: Screen always reads the wettest (highest) programmed
moisture calibration value while displaying dew/frost point.
Probe is saturated. Liquid
water present on sensor
surface and/or across
electrical connections.
Shorted circuit on sensor.
Sensor is contaminated with
conductive particles
(refer to Application of the
Hygrometer).
Improper cable connection.
Symptom: Screen always reads the driest (lowest) programmed
moisture calibration value while displaying dew/frost point.
Open circuit on sensor.
Non-conductive material is
trapped under the contact
arm of the sensor.
Improper cable connection.
158
System
Response
Probe reads too Return the probe to the factory for
wet or too dry. evaluation.
Probe reads too Return the probe to the factory for
dry. evaluation.
Probe reads too Return the probe to the factory for
wet or too dry evaluation.
Clean the sensor and the sensor shield as
described in Aluminum Oxide Probe Main-
tenance in Application of the Hygrometer.
Then reinstall sensor.
Run "dry gas" over sensor surface. If high
reading persists, then probe is probably
shorted and should be returned to the
factory for evaluation.
Clean the sensor and the sensor shield as
described in Aluminum Oxide Probe
Maintenance in Application of the
Hygrometer. Then reinstall sensor.
Check the cable connections to both the
probe and the PM880.
Return probe to factory for evaluation.
Clean the sensor and the sensor shield as
described in Aluminum Oxide Probe
Maintenance in Application of the
Hygrometer. Then reinstall the sensor. If the
low reading persists, return the probe to the
factory for evaluation.
Check the cable connections to both the
probe and the PM880.
Model PM880 Portable Hygrometer User's Manual
Action