Echosounder Fishfinding Problems - Simrad NX40 Installation & Operation Manual

• Check that the paddlewheel on the
transducer is spinning freely and that
the two magnets in the paddlewheel
are still in place.
B-4 echosounder fishfinding
problems
4-1 The unit operates erratically:
• Check that the transducer does not
have debris (e.g. weed, plastic bag)
caught around it.
• The transducer
damaged during launching, running
aground or
debris etc. If the transducer has been
impacted, it may have been kicked up
on the bracket. If it is not physically
damaged, reset the transducer back to
its original position.
• When the transducer is less that 2 ft
(0.6 m) from the bottom, the depth
readings may become inconsistent and
erratic.
• Manual Gain may be set too low, which
may cause weak bottom echo or no fish
signals. If in Manual Gain, try increasing
the Gain.
• Ensure the back of the bottom surface
of the transducer is slightly lower than
the front and the front is as deep in
the water as possible in order to
minimize the generation of bubbles
through cavitation. (See the Transom
Transducers Installation Guide)
• Check the
cable connectors at the back of the
display unit are securely plugged in
and the collars are locked in place. The
collars must be secure for watertight
connection.
• Inspect the power cable from end to
end for damage such as cuts, breaks,
squashed or trapped sections.
• Ensure there is not another fishfinder
or echosounder turned on, which may
interfere with this unit.
• Electrical noise from the boat's engine
or an accessory may be interfering with
the transducer(s) and/or the unit. This
may cause the unit to automatically
110
may have
while underway
transducer and
Simrad NX40/45 Installation and Operation Manual
decrease the Gain unless using Manual
Gain.
• The unit thus eliminates weaker signals
such as fish or even the bottom from
the display. This may be checked
by switching off other instruments,
accessories (e.g. bilge pump) and
the motor until the offending device
is located. To stop problems from
electrical noise, try:
• - re-routing the power and transducer
cable(s) away
been
other electrical wiring.
with
• - routing the display unit's power
cable directly to the battery with an in-
line fuse.
4-2 Bottom is not shown:
• The unit may have Manual Range
selected
outside the range value selected.
Either change the unit to Auto Range
or select another depth range.
• The depth may be outside the unit's
range. While in Auto Range, the display
unit will display "--.-" to indicate that
there is no bottom detected. A display
of the bottom should reappear when in
shallower water.
4-3 The bottom is shown too far up the
screen:
• The unit may have Manual Range
selected
value is too high for the depth. Either
change the unit to Auto Range or
power
select another depth range.
4-4 Bottom echo disappears or erratic
digital
moving:
• Ensure the back of the bottom surface
of the transducer is slightly lower
than the front and the front is as deep
in the water as possible in order to
minimise the generation of bubbles
through cavitation. (See the Transom
Transducers
more information.)
• The transducer may be in turbulent
water. Air bubbles in the water disrupt
the echoes returned, interfering with
from the boat's
and the depth
and the selected
reading while
Installation
may be
Range
the boat is
Guide, for