Humminbird 947C - Manual (Page 85)

80
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 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 boats engine may be interfering with sonar reception. See Finding the Cause of Noise for more
information.
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