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5. TROUBLESHOOTING
Maintenance and troubleshooting of Geokon Vibrating Wire Embedment Jointmeters is
confined to periodic checks of cable connections and maintenance of terminals. Once
installed, the Jointmeters are usually inaccessible and remedial action is limited. Consult the
following list of problems and possible solutions should difficulties arise. Consult the
factory for additional troubleshooting help.
Symptom: Jointmeter 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 transducer shaft of the Jointmeter positioned outside the specified range of the
instrument? Note that when the transducer shaft is fully retracted with the alignment pin
inside the alignment slot (Figure 1) the readings will likely be unstable because the
vibrating wire is now out of range.
Is there a source of electrical noise nearby? Most probable sources of electrical noise are
motors, generators, transformers, arc welders and antennas. Make sure the shield drain
wire is connected to ground whether using a portable readout or datalogger. If using the
GK-401 Readout connect the clip with the green boot to the bare shield drain wire of the
pressure cell cable. If using the GK-403 connect the clip with the blue boot to the shield
drain wire.
Symptom: Jointmeter Fails to Read
Is the cable cut or crushed? This can be checked with an ohmmeter. Nominal resistance
between the two transducer leads (usually red and black leads) is 180
,
10
.
Remember to add cable resistance when checking (22 AWG stranded copper leads are
approximately 14.7
/1000' or 48.5
/km). If the resistance reads infinite, or very high
(>1 megohm), a cut wire must be suspected. If the resistance reads very low (
100
) a
short in the cable is likely. Splicing kits and instructions are available from the factory to
repair broken or shorted cables. Consult the factory for additional information.
Does the readout or datalogger work with another Jointmeter? If not the readout or
datalogger may be malfunctioning.
