Check surface potential reference (lead oxide flag) to make sure it is buried in moist soil and that the
wire from it is not frayed or broken.
If SP fluctuates badly, stray ground potentials are the cause; this is a situation encountered in highly
industrialized areas. To remedy this situation, use the lateral arrangement of electrodes.
Unable to Zero the Meter with Self-Potential Potentiometer:
Be sure you have tried reversing the SP polarity switch. To zero the galvanometer the injected
voltage must be of proper polarity. Note that the polarity of the SP may change during the logging.
Check the voltage of the 1 1/2 volt "C" battery. Replace it if necessary.
No Meter Response to Self-Potential Potentiometer:
Check all plug-in connections and surface lines, in particular, the potential surface line where it is
connected to the lead flag.
Check the SP shut-off switch. Occasionally if the instrument has not been used for some time, this
switch may have become stuck in the off position (depressed). Pushing the button up and down with
your finger a couple of times will release the switch.
Meter Deflection with no Connections to Instrument:
a. This condition will be present when water has entered the current switch thereby maintaining an
electrical connection within the switch without the switch being activated. When this happens, the
switch needs only to be dried with the application of some heat to the switch. Should this happen
frequently, a rubber boot should be installed on the switch.
b. NOTE: Although this condition is not normal, if proper calibration and operation of the unit can be
effected with the test set, then the instrument will operate properly when the current switch is
2-4.4 Battery Voltage Check Using a Voltmeter
The following checks are made with the test set connected.
Single 9 Volt Battery: With voltmeter function switch at +DC volts and range switch at full scale reading closest
to, but no lower than 10 volts, connect Red (+) lead to positive terminal (male) and Black (-) lead to the opposite
(female) terminal of the battery. Record this open circuit voltage. Place function switch in CUR or CAL mode,
energize the current switch, and record the battery voltage under load. The voltage should remain at or slightly
below the open circuit voltage. If the voltage should continue to change value when the current switch is
energized, the battery is defective (weak) and should be replaced.