Humminbird 737 GPS manual Display Problems, Finding the Cause of Noise

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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

The control head loses power

If the power output of your boat’s engine is

at high speeds.

unregulated, the control head may be protecting itself

 

using its over-voltage protection feature. Make sure the

 

input voltage does not exceed 20 Volts.

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 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

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.

The transducer position may need to be adjusted. A mix of air and water flowing around the transducer (cavitation) may be interfering with the interpretation 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.

 

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 noise;

propeller

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 Atic Thank You Table of ContentsKey Functions Views Menu Tab Accessories Menu Tab How Sonar Works Peak to Peak measures power output at the highest pointsWith optional-purchase WideSide transducer QuadraBeam SonarDualBeam Plus Sonar WideSide SonarWith optional-purchase GPS Receiver Software UpdatesHow GPS and Cartography Work Multi-Media Card MMC/SD Slot83 kHz, Wide Beam Hollow Fish Symbol What’s On the DisplaySoft Bottom RTS Real Time Sonar Window Views Sonar ViewSonar views Freeze Frame Understanding Sonar HistoryReal Time Sonar RTS Window Bottom PresentationSonar Zoom View Sonar Zoom ViewBig Digits View 200/83 kHz Split Sonar View 200/83 kHz Split Sonar ViewBig Digits View Circular Flasher ViewScreen Capture View Screen Snapshot ViewSide Beam View Making a Screen SnapshotBird’s Eye View WideSide ViewDepth Chart View without Active CursorChart View with Active Cursor Combo ViewWaypoints, Routes and Tracks Viewing CartographySave, Edit, or Delete a Waypoint Add a Waypoint Target or Trolling Grid Chart View with GridInfo Key POWER/LIGHT KeyKey Functions View KeyGoto Key Accessory BusWAY Cursor Control Key Mark KeyPowering Up the Unit Menu SystemPresence or absence of a transducer Simulator Start-Up Options MenuNormal Operation System StatusAccessory Test Exit PC Connect mode by powering the Fishing System offGPS Diagnostic View WideSide transducer WideSide view only To adjust the SideSonar X-PressTMMenu SideUpper Range To adjust the SensitivityTo adjust the Upper Range SensitivityChart Speed Lower RangeSide Beam Range Bottom Lock Cancel NavigationBottom View Bottom RangeTo view the Waypoint Name Submenu Navigation X-PressTM MenuWaypoint Name Only with an active cursor on a waypointSave Current Route Cursor to WaypointSave Current Track Clear Current TrackRemove Target Remove GridSonar Window Sonar Menu Tab Screen Snapshot X-Press TM MenuDelete Image Delete All ImagesHighlight Beam Select on the Sonar main menu Beam SelectFish ID+TM To use Beam SelectAdvanced Fish ID SensitivityZoom Width KHz SensitivityAdvanced with WideSide transducer KHz BalanceWideSide Sensitivity Depth LinesSurface Clutter Noise FilterMax Depth Navigation Menu Tab To change the Water Type settingWater Type Transducer SelectCurrent Track Saved TracksWaypoints Grid Rotation Chart OrientationRoutes North ReferenceExport All Nav Data Track Min DistanceMap Datum Course Projection LineWith optional-purchase GPS Receiver only Chart Menu TabChart Detail Level Map BordersSet Map Offset Lat/Lon GridSpot Soundings Set Simulation PositionTo change the Depth Alarm setting Alarms Menu TabDepth Alarm Fish ID AlarmArrival Alarm Low Battery AlarmTemp Alarm Off Course AlarmTo change the Drift Alarm setting Drift AlarmAlarm Tone Setup Menu TabUnits Distance User ModeUnits Depth Units TempAdvanced, Sonar view only Triplog ResetRestore Defaults Select ReadoutsPosition Format Depth OffsetTemp Offset Speed Calibration Sonar Time Format Date Format Nmea OutputTo Change the View Status of Any View Accessories Menu TabUsing Screen Snapshot Views Menu TabTroubleshooting To make a screen snapshot Screen Snapshot must be enabledTo view screen snapshots Finding the Cause of Noise Display ProblemsSpecifications Series Fishing System AccessoriesSonar Terms Glossary100 102 Receiver See Transmitter104 GPS & Navigation Terms 108 Contact Humminbird
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