7. TROUBLESHOOTING
Maintenance and troubleshooting of concrete stressmeters is confined to periodic checks of cable
connections and maintenance of terminals. Once installed, the gages 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: Strain gauge 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 strain reading outside the specified range (either compressive or tensile) of the
instrument?
Is there a source of electrical noise nearby? Most probable sources of electrical noise are
motors, generators and antennas. Move the equipment away from the installation or install
electronic filtering. Make sure the shield drain wire is connected to ground whether using a
portable readout or datalogger.
Does the readout work with another gauge? If not, the readout may have a low battery or be
malfunctioning.
Symptom: Strain gauge Fails to Read
Is the cable cut or crushed? This can be checked with an ohmmeter. Nominal resistance
between the two gauge leads (usually red and black leads) is 50
Ω
,
±
10
Ω
. Remember to add
cable resistance when checking (22 AWG stranded copper leads are approximately 14.7
Ω
/1000' or 48.5
Ω
/km, multiply by two for both directions). If the resistance reads infinite, or
very high (megohms), a cut wire must be suspected. If the resistance reads very low (
<
10
Ω
) 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 strain gauge? If not, the readout or
datalogger may be malfunctioning.