Humminbird 1197C SI - Manual (Page 180)

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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