6.Troubleshooting

Maintenance and troubleshooting is confined to periodic checks of cable connections and maintenance of terminals. Once installed, these instruments are usually inaccessible and remedial action is limited. Should difficulties arise, consult the following list of problems and possible solutions. Return any faulty gauges to the factory. Instruments should not be opened in the field. 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 located in the cable, splice according to instructions in Section 3.1.

Symptom: Thermistor resistance is too low

□Check for a short circuit. Check all connections, terminals, and plugs. If a short is located in the cable, splice according to instructions in Section 3.1.

□Water may have penetrated the interior of the instrument. There is no remedial action.

Symptom: Instrument Readings are Unstable

□Is the readout box position set correctly? If using a datalogger to record readings automatically, are the swept frequency excitation settings correct?

□Is the instrument shaft positioned outside the specified range (either extension or retraction) of the instrument? When the shaft is fully retracted with the alignment pin inside the alignment slot, the readings will likely be unstable because the vibrating wire is under-tensioned.

□Is there a source of electrical noise nearby? Likely candidates are generators, motors, arc welding equipment, high voltage lines, etc. If possible, move the instrument cable away from power lines and electrical equipment or install electronic filtering.

□Make sure the shield drain wire is connected to ground. Connect the shield drain wire to the readout using the blue clip.

□Does the readout or datalogger work with another instrument? If not, it may have a low battery or possibly be malfunctioning.

Symptom: Instrument Fails to Read

□Does the readout or datalogger work with another instrument? If not, it may have a low battery or possibly be malfunctioning.

□Is the cable cut or crushed? Check the resistance of the cable by connecting an ohmmeter to the sensor leads; resistance is approximately 48.5Ω per km (14.7Ω per 1000') of 22 AWG wire.

If the resistance is very high or infinite, the cable is probably broken. If the resistance is very low, the conductors may be shorted. If a break or a short is present, splice according to the instructions in Section 3.1.

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

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