Power Connection; Operation; Range Select - Lowrance 1240A Installation And Operation Instructions Manual

POWER CONNECTION

12-volt DC power for the 1240A is supplied from the boat's 12-volt electrical
system. You can connect the power either from an existing fuse block that's
behind the dash or directly to the battery. An in-line fuse holder is supplied
with the unit in case a fuse is not available. Attach the fuse holder as close
to the power source as possible. This will help protect both the unit and the
power cable in the event of a short circuit.
Caution! Never connect this unit to power without a fuse!
The positive wire is red. The negative wire is black and should be attached
to the negative ground buss or the negative side of the battery.
This unit is protected from accidental polarity reversal and no damage will
result if the battery connections are wrong. However, the unit will not work
until correct polarity is applied.

OPERATION

To turn the sonar on, rotate the large control knob from the "off" position
to either 40 feet or 100 feet. This is a three-position switch and controls both
power on/off and range select. To turn the sonar off, rotate the switch back
to the "off" position.

RANGE SELECT

There are two scales on the 1240A - 0 to 40 feet and 0 to 100 feet. Make
the selection by turning the large knob to the 40 or 100 setting. Depths
greater than 100 feet can also be measured. For instance, as the water
depth goes from 90 to 110 feet, you will see the bottom signal on the dial
move past the "zero" signal to the 10-foot mark. Thus, on the second
revolution, depths of 100 to 200 feet can be read by adding 100 feet to the
reading on the dial.
SENSITIVITY CONTROL
(Pull Out for Maximum
Suppression)
RANGE AND POWER
ON/OFF