Finding the Cause of Noise

Electrical noise usually affects the display with many black dots at high speeds, and high sensitivity readings. One or more of the following sources can cause noise or interference:

Possible Source of NoiseIsolation
Other electronic devices

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.

The boat’s engine

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 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.
Cavitation from the boat’s propeller

Turbulence created by the propeller can cause noise; make sure the transducer is mounted at least 15” (38 cm) from the propeller, and that the water flows smoothly over the face of the transducer at all times.

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Troubleshooting