Humminbird 798ci Manuel D’Utilisation
175
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:
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.
power at high speeds.
When the boat moves
at higher speeds, the
bottom disappears or
suddenly weakens, or
the display contains
gaps.
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.
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 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.
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.
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.
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.
transmission.
Electrical noise from the boat’s engine may be interfering
with sonar reception. See Finding the Cause of Noise for
more information.
with sonar reception. See Finding the Cause of Noise for
more information.
Troubleshooting