Display Problems - Humminbird ONIX8 Installation Manual

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:
Display Problems
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.
Finding the Cause of Noise
Electrical noise usually affects the display with many black dots at high speeds, and high sensitivity readings. See the table below for
possible sources that can cause noise or interference.
Possible Source of Noise
Other electronic devices
The boat's engine
Cavitation from the boat's propeller
Troubleshooting
Possible Solutions
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 the installation section for your transducer for instructions 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. See the installation section for your transducer for instructions
on adjusting the transducer position, 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.
Isolation
Turn off any nearby electronic devices to see if the problem goes away, then turn them
on one at a time to see if the noise re-appears.
To determine whether the boat's engine is the source of the noise, increase the RPMs
while the boat is in neutral and stationary to see if the noise increases proportionately;
if the noise appears when you rev the engine, the problem could be the spark plugs,
alternator, or tachometer wiring. Replace the spark plugs with resistor plugs, install an
alternator filter, or route the control head power and transducer cables away from the
engine wiring.
Turbulence created by the propeller can cause noise. Confirm the transducer has been
properly installed according to its specific mounting requirements (see Transom
Transducer Mounting Requirements and Side Imaging Transducer Mounting
Requirements). Also, make sure that the water flows smoothly over the face of the
transducer at all times.
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