7.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. Gauges 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

□Check for an open circuit. Check all connections, terminals, and plugs. If a cut is in the cable, splice according to instructions in Section 4.6.

Symptom: Thermistor resistance is too low

□Check for a short circuit. Check all connections, terminals, and plugs. If a short is in the cable, splice according to instructions in Section 4.6.

□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.

□Isolate the readout from the ground by placing it on a piece of wood or another 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 over-ranging 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 gauge conductors may be shorted.

Symptom: Piezometer fails to give a reading

□Check the readout with another gauge to ensure it is functioning properly.

□The piezometer may have been over-ranged or shocked. Inspect the diaphragm and housing for damage.

□Check the resistance of the cable by connecting an ohmmeter to the sensor leads. Cable resistance is about 48.5Ω per km (14.7Ω per 1000').

If the resistance is very high or infinite, the cable is probably broken. If the resistance is very low, the gauge conductors may be shorted. If a break or a short is present, splice according to the instructions in Section 4.6.

Refer to the expected resistance for the various wire combinations below.

Any other wire combination will result in a measurement of infinite resistance.