Humminbird 767 manual Display Problems, Finding the Cause of Noise

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531427-1_C - 767_Man_Eng.qxd 10/25/2005 10:30 AM Page 102

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

Other electronic devices

Turn off any nearby electronic devices to see if the

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 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.

 

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 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 GPS Chartplotter Operations Manual Table of Contents Thank YouKey Functions Views Menu Tab Accessories Menu Tab Peak to Peak measures power output at the highest points How Sonar WorksDualBeam Plus Sonar QuadraBeam SonarWideSide Sonar With optional-purchase QuadraBeamTM transducerHow GPS and Cartography Work Software UpdatesMulti-Media Card MMC/SD Slot 200 KHz WithF f e r e n t Bait Ball Hard Bottom Rocky BottomDistance distance Traveled withAverage Speed Average speed readingZoom View Chart View 200/83 kHz Split Sonar View ViewsSonar View Sonar viewsUnderstanding Sonar History Real Time Sonar RTS WindowFreeze Frame Bottom PresentationSonar Zoom View Sonar Zoom View200/83 kHz Split Sonar View Circular Flasher ViewScreen Snapshot View Big Digits ViewSide Beam View Side Beam ViewWideSide View Bird’s Eye ViewBird’s Eye View Combo View Chart ViewView Orientation Viewing Cartography Waypoints, Routes and TracksSave, Edit, or Delete a Waypoint Navigate to a Waypoint or PositionSave, Edit or Delete a Route Save or Clear a Current TrackAdd a Waypoint Target or Trolling Grid Press menuPOWER/LIGHT Key Edit, Delete or Hide Saved TracksKey Functions View KeyAccessory Bus WAY Cursor Control KeyMark Key Goto KeyMenu System Powering Up the UnitTitle Screen Normal Operation Start-Up Options MenuSimulator GPS Diagnostic View Accessory TestSystem Status Self TestTo adjust the Side Sonar X-PressTMMenuSide Sonar views onlyTo adjust the Sensitivity To adjust the Upper RangeSensitivity Upper RangeLower Range Chart SpeedSide Beam Range Cancel Navigation Bottom ViewBottom Range Bottom LockNavigation X-PressTMMenu Waypoint NameNavigation views only Only with an active cursor on a waypointCursor to Waypoint Save Current TrackClear Current Track Save Current RouteRemove Grid Remove TargetSonar Window Screen Snapshot X-PressTMMenu Sonar Menu TabDelete Image Delete All ImagesBeam Select Fish ID+TMTo use Beam Select To turn Fish ID+ on or offFish ID Sensitivity Zoom WidthKHz Sensitivity KHz BalanceTo change the 455 kHz Balance setting To change the Depth Lines settingWideSide Sensitivity Depth LinesNoise Filter Surface ClutterMax Depth To change the Water Type setting Water TypeTransducer Select Navigation Menu TabSaved Tracks Current TrackWaypoints Chart Orientation RoutesNorth Reference Grid RotationTrack Min Distance Map DatumCourse Projection Line Export All Nav DataChart Menu Tab Chart Detail LevelTo change the Chart Detail Level setting To change the Map Borders settingLat/Lon Grid Spot SoundingsSet Simulation Position Set Map OffsetAlarms Menu Tab Depth AlarmFish ID Alarm To change the Depth Alarm settingLow Battery Alarm Temp AlarmOff Course Alarm Arrival AlarmSetup Menu Tab Drift AlarmAlarm Tone User Mode Units DepthUnits Temp Units DistanceTriplog Reset Restore DefaultsSelect Readouts Advanced, Sonar view onlyDepth Offset Temp OffsetSpeed Calibration Advanced, with Temp/Speed onlyPosition Format Time FormatDate Format Nmea OutputAccessories Menu Tab Using Screen SnapshotViews Menu Tab To Change the View Status of Any ViewTo make a screen snapshot Screen Snapshot must be enabled TroubleshootingTo view screen snapshots Display Problems Finding the Cause of NoiseSeries Fishing System Accessories SpecificationsGlossary Sonar Terms100 Receiver See Transmitter 104 GPS & Navigation Terms Magnetic North Contact Humminbird
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