2-4.1 Introduction. A "test set" is provided so that you can check the instrument's operation independent of the cable
assembly. If the instrument reads the correct value for the test set, then the instrument itself is functioning properly and
the trouble is somewhere other than in the electronics of the instrument. To use the test set, plug it into the instrument as
described under "Test Set", paragraph 2-1.5, then follow the operating instructions in paragraph 2-2. The electrode
selector switch must be in one of the normal logging positions.
2-4.2 Checking Batteries. With the test set plugged into the instrument, turn the function switch to the CAL position and
try to calibrate the instrument:
If the instrument can be calibrated, then turn the function switch to CUR and check the current by throwing
the current switch; if the current flowing is less than 8 ma. (full scale on meter = 25 ma.) then the complete
set of six, 9 volt batteries should be replaced.
If the instrument cannot be calibrated, the complete set of six, 9 volt batteries should be replaced. (Figure
Refer to battery voltage checking procedure to check the batteries with a voltmeter.
2-4.3 Troubleshooting Procedures. Commonly encountered troubles are listed below along with the corrective
Unable to Calibrate Instrument: Most often caused by insufficient or no current flowing in the ground circuit.
Check conditions of batteries, replace if necessary.
Check all lines and plugs for bad connections.
Sometimes insufficient current is the result of high resistance at the steel surface current electrode.
If the galvanometer shows less than 9 ma. and it cannot be increased by rotating the cal adjust
knob, then the contact resistance at the steel stake is too high. Reduce the resistance by driving it
deeper or pour water around it or double stake until an excess of 8 ma. can be obtained.
If at least 8 ma. cannot be obtained, the ground circuit is too highly resistive (a situation
encountered in areas having a thick cover of dry sand or where there is frost on the ground) and
obtaining a log in these situations requires the use of the lateral arrangement of electrodes with the
CUR wires connected to the well casing.
Fluctuation SP: Galvanometer needle fluctuates uncontrollably when function switch is in the log position.