Humminbird 300 series, 323 Display Problems, Finding the Cause of Noise, Problem Possible Cause

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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:

Problem

Possible Cause

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

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.

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 inter- pretation of sonar data. See your Installation Guide for suggestions 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. Check with your Installation Guide for guidance on re-positioning the transducer, and make sure the transducer is clean.

Low battery voltage may be affecting the power of signal transmission.

Electrical noise from the boat’s engine may be interfering with sonar reception. See Finding the Cause of Noise for more information.

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

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 Operations Manual Thank You Table of ContentsSpecifications Glossary Contact Humminbird Alarms Menu TabSetup Menu Tab TroubleshootingHow Sonar Works DualBeam Plus Sonar Bait Ball Hard Bottom Rocky Bottom What’s On the DisplaySoft Bottom RTS Real Time Sonar Window Temperature water Do Not print this Sonar View ViewsReal Time Sonar RTS Window Understanding Sonar HistoryFreeze Frame Bottom Presentation 200/83 kHz Split Sonar View Sonar Zoom ViewCircular Flasher View POWER/LIGHT KeyBig Digits View Key FunctionsExit Key Powering Up the UnitMenu Key WAY Cursor Control KeyMenu System Sonar Tab, Normal Mode Sonar Tab, Advanced ModeNormal Operation Start-Up Options MenuSimulator Operation and the input voltage Accessory Test lists the accessories connected to SystemExit System Status by powering your Fishing System off System Status Sonar X-PressTMMenuUpper Range To adjust the SensitivityTo adjust the Upper Range SensitivityLower Range Chart SpeedTo adjust the Lower Range To adjust the Chart SpeedBottom Lock Zoom LevelBottom Range Highlight Beam Select on the Sonar main menu Sonar Menu TabBeam Select To use Beam SelectFish ID Sensitivity To change the Fish ID Sensitivity settingTo change the RTS Window setting Fish ID+TMKHz Sensitivity Zoom WidthDepth Lines Noise Filter Surface ClutterMax Depth To change the Water Type setting Alarms Menu TabWater Type Temp Alarm Depth AlarmFish ID Alarm Low Battery AlarmHighlight Alarm Tone on the Alarms main menu Alarm ToneSetup Menu Tab To change the Alarm Tone settingUnits Distance User ModeUnits Depth Units TempRestore Defaults Triplog ResetSelect Views Depth Offset Select ReadoutsTemp Offset To change the Speed Calibration setting TroubleshootingSpeed Calibration Isolation Display ProblemsProblem Possible Cause Finding the Cause of NoiseGlossary SpecificationsSonar Terms 531444-1A 323ManEnglish.qxd 11/5/2005 1234 PM 531444-1A 323ManEnglish.qxd 11/5/2005 1234 PM Receiver See Transmitter 531444-1A 323ManEnglish.qxd 11/5/2005 1234 PM Contact Humminbird
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