24
6. TROUBLESHOOTING
Maintenance and troubleshooting of vibrating wire piezometers is confined to periodic checks of
cable connections and maintenance of terminals. The transducers themselves are sealed and are
not user serviceable.
Gages should not be opened in the field.
Should difficulties arise, consult the following list of problems and possible solutions. For
additional troubleshooting and support, contact Geokon.
Symptom: Thermistor resistance is too high
Likely, there is an open circuit. Check all connections, terminals, and plugs. If a cut is
located in the cable, splice according to instructions in Section 3.3.
Symptom: Thermistor resistance is too low
A short is likely. Check all connections, terminals, and plugs. If a short is located in the
cable, splice according to instructions in Section 3.3.
Water may have penetrated the interior of the piezometer. There is no remedial action.
Symptom: Piezometer reading unstable
Make sure the shield drain wire is connected to the blue clip on the flying leads. (Green for
the GK-401.)
Isolate the readout from the ground by placing it on a piece of wood or other insulator.
Check for sources of nearby electrical noise such as motors, generators, antennas, or
electrical cables. Move the piezometer cable away from these sources if possible. Contact the
factory for available filtering and shielding equipment.
The Piezometer may have been damaged by overranging or shock. Inspect the diaphragm and
housing for damage.
The body of the Piezometer may be shorted to the shield. Check the resistance between the
shield drain wire and the Piezometer housing. If the resistance is very low, the gage
conductors may be shorted.
Symptom: Piezometer fails to give a reading
Check the resistance of the cable by connecting an ohmmeter to the sensor leads. Table 3
shows the expected resistance for the various wire combinations; Table 4 is provided for the
customer to fill in the actual resistance found. Cable resistance is approximately 14.7
Ω
per
1000' of 22 AWG wire. Multiply this factor by two to account for both directions.
If the resistance is very high or infinite, the cable is probably broken or cut. If the resistance
is very low, the gage conductors may be shorted. If a cut or a short is located in the cable,
splice according to instructions in Section 3.3.
Check the readout with another gage to ensure it is functioning properly.
The Piezometer may have been overranged or shocked. Inspect the diaphragm and housing
for damage.
