NorthStar Navigation Explorer 660 - Manual (Page 72)

Northstar Explorer 660 Installation and Operation Manual 72
g Inspect the power cable from end to end for
damage such as cuts, breaks, squashed or
trapped sections.
h Ensure there is not another fishfinder or
depth sounder turned on, which may
interfere with this Explorer 660.
i Electrical noise from the boat’s engine or
an accessory may be interfering with the
transducer(s) and/or the Explorer 660. This
may cause the Explorer 660 to automatically
decrease the Gain unless using Manual Gain.
The Explorer 660 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 from the boat’s other electrical wiring.
- routing the display unit’s power cable directly
to the battery with an in-line fuse.
3-2 Bottom is not displayed:
a The Explorer 660 may have Manual Range
selected and the depth may be outside the
range value selected. Either change the
Explorer 660 to Auto Range or select another
depth range (see section 8-5).
b The depth may be outside the Explorer 660’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.
3-3 The bottom is displayed too far up
the screen:
The Explorer 660 may have Manual Range
selected and the selected Range value is
too high for the depth. Either change the
Explorer 660 to Auto Range or select another
depth range (see section 8-5).
3-4 Bottom echo disappears or erratic digital
reading while the boat is moving:
a 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 Installation Guide, for
more information.)
b The transducer may be in turbulent water.
Air bubbles in the water disrupt the echoes
returned, interfering with the Explorer
660’s ability to find the bottom or other
targets. This often happens when the boat is
reversed. The transducer must be mounted
in a smooth flow of water in order for the
Explorer 660 to work at all boat speeds.
c Electrical noise from the boat’s motor can
interfere with the Explorer 660. Try some
suppression spark plugs.
3-5 There is a double bottom trace displayed:
a The boat may be in an area that generates
shadows (see section 8-2).
b In shallow water, the echoes may bounce. Reduce
the gain setting (see section 8-5) and/or reduce
the sonar pulse power (see section 15-3).
c Decrease the Range.