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Electrical Interference Troubleshooting
There may be situations where you experience interference from other
electrical devices, not just from another nearby depth sounder. This
interference will show on the display as random signals and interfere with
your ability to see normal display signals. The most common sources of
interference are electric trolling motors and engine ignitions systems.
Your flasher’s IR feature won’t help much, as this is designed for cross-
talk, but here are some tips that might.
Sources
Interference can be introduced into your sonar system through the
power supply, transducer line or both. To identify the source, unplug the
transducer and run the trolling motor or the engine. If the interference
disappears, you know the noise is coming in through the transducer line.
If not, it’s coming through the power line or both.
Wiring
Power line interference can generally be solved by improvements in the
wiring positions, connections and grounding. You want to be sure the
sonar wiring is as far away as possible from the trolling motor wiring and
that the wiring is neat. Make cable runs as short as possible and neatly coil
extra wire and tie it off so it stays put in rough water or while pulling the
boat. All electrical connections should be in very good condition. Push-on
terminals should be tight. Wire crimp connections should not come free
when pulled firmly. Conductors should be shiny, not dull or corroded.
Grounding
The boat’s electrical system should have a common “Earth” ground to
the water. In most boats, the electrical system is grounded through the
outboard to the water. Many times an electric trolling motor interference
problem can be solved by a “ground” wire from the negative trolling motor
power source to the negative of the starting battery.
Equipment
Electric trolling motors and gas engines can have technical problems that
can cause interference. If common wiring improvements do not solve the
problem, be sure to check with the manufacturer to see if there are any
recommendations or updates available regarding interference with depth
sounders.
Summary of Contents for FL-18
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