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 Noise | Isolation |
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 reappears. |
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 | Turbulence created by the propeller can cause |
propeller | 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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