Humminbird 515, 500 series manual Finding the Cause of Noise, Isolation

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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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Contents Series Operations Manual Thank You Table of Contents Alarms Menu Tab Troubleshooting How Sonar Works Peak to Peak measures power output at the highest points Single Beam Sonar DualBeam SonarQuadraBeam Plus Sonar What’s On the Display Bait Ball Hard Bottom Rocky BottomStructure where fish may be hiding Views Big Digits View Side Beam View 575 Fishfinder onlySonar View Understanding Sonar History Real Time Sonar RTS WindowBottom Presentation Page Page Sonar Zoom View Sonar Zoom View200/83 kHz Split Sonar View Big Digits View Side Beam View Water Surface Line for 455 kHz Sonar History Windows Page Key Functions POWER/LIGHT KeyView Key WAY Cursor Control Key Menu KeyExit Key Powering Up the Unit 575Menu System Page Start-Up Options Menu Normal OperationSimulator System Status Self TestAccessory Test Sonar X-Press Menu Sensitivity Upper Range Advanced Sonar, Split Sonar, Big Digits Views onlyLower Range Chart Speed Bottom View Quad Layout Zoom LevelSonar Menu Tab Beam Select Fish ID+ Fish ID Sensitivity Zoom Width KHz SensitivityKHz Balance Depth Lines AdvancedSurface Clutter Noise Filter Max DepthWater Type Alarms Menu Tab Depth Alarm Fish ID AlarmLow Battery Alarm Temp AlarmAlarm Tone Setup Menu Tab Units Temp Units DepthUnits Distance Units Speed User ModeLanguage Triplog Reset Restore DefaultsSelect Views Select Readouts Advanced Sonar View onlyDepth Offset Temp Offset Speed CalibrationTroubleshooting Series Doesn’t Power UpDisplay Problems Problem Possible CauseFinding the Cause of Noise IsolationSeries Fishfinder Accessories Specifications 800 ft 250 mPolicy on Environmental Compliance Glossary Sonar TermsPage Page Page Page Receiver See Transmitter Page Page Page Page Page Page Page Page Page Page Page Page Contact Humminbird