Humminbird 1158c Combo, Installation And Operation Manual

Page: 216 / 232

Display Problems
There are several main conditions or sources of possible interference that may cause problems
with the quality of the information displayed on the control head. Look in the following table for
some symptoms of display problems and possible solutions:
Problem Possible Cause
The control head loses
power at high speeds.
When the boat moves
at higher speeds, the
bottom disappears or
suddenly weakens, or
the display contains
gaps.
There are no fish
detected, even when
you know they are in
the water under the
boat, or sonar readings
seem weak or faulty.
If the power output of your boat’s engine is unregulated, the
control head may be protecting itself using its over-voltage
protection feature. Make sure the input voltage does not
exceed 20 Volts.
The transducer position may need to be adjusted. A mix of air
and water flowing around the transducer (cavitation) may be
interfering with the interpretation of sonar data. See your
Installation Guide for suggestions on adjusting the transducer
position.
Electrical noise from the boat’s engine may be interfering
with sonar reception. See
Finding the Cause of Noise for
more information.
Sonar readings may be affected if the transducer is not
positioned correctly (i.e. mounted at an angle, not straight
down), or there is some kind of mechanical interference,
either because it is mounted inside a hull that is too thick for
proper sonar transmission, the bond between the transducer
and the hull is not airtight, or because the transducer is dirty.
Check with your Installation Guide for guidance on re-
positioning the transducer, and make sure the transducer is
clean.
Low battery voltage may be affecting the power of signal
transmission.
Electrical noise from the boats engine may be interfering with
sonar reception. See
Finding the Cause of Noise for more
information.
Troubleshooting
204