Recalibration; Troubleshooting - GE Bently Nevada 7200 Series Installation Manual

14 mm Proximity Transducer System 7200 Series Installation Manual

3.3 RECALIBRATION

Perform the following procedure to recalibrate the transducer.
a. Remove the protective assembly from the calibration resistor on the Proximitor (use a
screwdriver to pry away the outer barrier). Desolder and remove the calibration resistor (see
Figure 3-1).
b. Attach the variable resistor between the calibration resistor terminals.
c. Perform the calibration check (Page 3-1) and adjust the variable resistor as appropriate until the
desired calibration curve is obtained.
Increasing the resistance between the calibration terminals will
decrease the Proximitor output voltage and slope of the calibration
curve; decreasing the resistance will cause the Proximitor output
voltage and slope of the calibration curve to increase.
d. When the desired average scale factor is obtained, remove the variable resistor from the
calibration terminals and use the digital multimeter to measure its resistance. Select a 1%
tolerance resistor (or two in parallel) equal to the measured resistance of the variable resistor.
e. Solder the resistor(s) between the calibration terminals.
To prevent damage to components, do not leave the soldering iron in
contact with the Proximitor terminals too long.
f. Remove the room-temperature vulcanizing compound from the epoxy fiberglass shroud.
g. Install the shroud over the calibration resistor(s) and encapsulate with room-temperature
vulcanizing compound that does not have an acid base.

3.4 TROUBLESHOOTING

The troubleshooting procedure in Table 3-2 helps the user interpret and isolate faults in an installed
transducer system. Before beginning the procedure, ensure the system has been installed correctly
and all connectors have been secured properly in the correct locations.
When a malfunction occurs, locate the fault indication in the left-hand column of Table 3-2. Then,
refer to the center column which lists the probable causes for each fault indication, and the right-
hand column which lists the procedure to isolate and correct the fault. Use a digital multimeter to
perform voltage and resistance measurements.
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CAUTION