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Finding the Cause of Noise
Electrical noise usuallyaffects the display withmany black dots at highspeeds, and
high sensitivity readings. One or more of the following sources can cause noise or
interference:
Possible Source of Noise Isolation
Other electronic devices
The boat’s engine
Cavitation from the boat’s
propeller
Turn off any nearby electronic devices to see if the
problem goes away, then turn them on one at a
time to seeif the noisere-appears.
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 revthe engine, the problemcould be thespark
plugs,alternator, or tachometer wiring. Replacethe
sparkplugs withresistor plugs, installanalternator
filter, or route the control head power and
transducer cables awayfrom the enginewiring.
Turbulence created by the propeller can cause
noise;makesure thetransduceris mountedatleast
15” (38 cm) from the propeller, and that the water
flows smoothly over the face of the transducer at
all times.