Humboldt H-4040 Series Water Level Indicators - Manual (Page 3)

CONTROL can be adjusted to compensate for varying conditions.
NOTE! After this unit has been in use for some time, you may find you have
to set the SENSITIVITY CONTROL toward the minus (-) sign to achieve good
results. This is an indication that the white tip of the probe is not shedding
water as well as it did originally.
MAXIMUM SELECTIVITY
Maximum selectivity is that point where the instrument can best differentiate
between the static water level and water that may be cascading from above.
Do the following to make the water level indicator be most selective:
Turn the power switch to ON.
Set the SENSITIVITY CONTROL mid-range or higher (toward + sign).
Lower the probe down the well or bore hole until the instrument indicates
you have contacted water. Leave the probe submerged with buzzer & light
operating.
Rotate the SENSITIVITY CONTROL counter-clockwise (toward -) until the
light and buzzer shut off.
Now slowly rotate the SENSITIVITY CONTROL clockwise (toward +), until
the light and buzzer start to function again. Try moving the probe in and out
of the water and observe the indicators on the front panel. The instrument
should respond with a solid on/off response. If that isn't happening, make a
final adjustment by rotating the knob clockwise very slightly.
MAINTENANCE - PROBE
Keeping the probe clean is essential for reliable operation. The white
plastic tip has to be clean and slippery enough to shed water quickly. This
is important because the instrument can sense any film of water that may
remain between the two sensing needles when the SENSITIVITY CONTROL
is at the higher settings.
Often a probe needs only to be washed in soapy water followed by a clear
water rinse. In extreme cases, use a non-abrasive liquid kitchen/bath cleaner
good for removing grease. Follow up with soap wash/clear water rinse.
Don't use strong chemicals/abrasives for cleaning. DO NOT DISASSEMBLE
THE PROBE!
BATTERY INSTALLATION
Remove the two (2) screws holding the round plate, located in the center of
the spool. This is the Electronic Control Module, which contains the buzzer,
LED indicator and switch. Remove the plate from the spool, being careful
not to damage the wires and components attached to the back of this panel.
Locate the batter connector, attached to the red and black wires.
Snap the connector onto the battery and place it in the bottom of the spool.
Make sure that there is a foam pad on each side of the battery and the black
pad is between the battery and the printed circuit board.
Re-install the Electronic Control Module (being careful not to pinch the
wires), and secure with the two (2) screws. (Do not over-tighten these
screws!)