Humminbird 425 SX - Manual (Page 32)

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ADVANCED FEATURES
TROUBLESHOOTING
7. My unit loses power at high speeds.
Your 425SX has over-voltage protection that turns the unit off when input voltage
exceeds 20 VDC. Some outboard motors do not effectively regulate the power
output of the engine’s alternator and can produce voltage in excess of 20 volts
when running at high RPMs. The 425SX displays input voltage in the Diagnostic
screen. Use this readout to determine if the voltage exceeds 20 VDC.
8. The screen begins to fade out. Images are not as sharp as
normal.
Check the input voltage using Diagnostic. The 425SX will not operate on input
voltages below 10 VDC.
9. The display shows many black dots at high speeds and high
sensitivity settings.
You are seeing noise or interference caused by one of several sources. Noise can
be caused by other electronic devices. Turn off any nearby electronics and see if
the problem goes away. Noise can also be caused by the engine. If engine noise
is causing the interference, the problem will intensify at higher RPMs. Increase the
engine speed with the boat stationary to isolate this cause. Propeller cavitation
can appear as noise on-screen. If the transducer is mounted too close to the
propeller, the turbulence generated can interfere with the sonar signal. Ensure
that the transducer is mounted at least 38cm (15") from the prop.
For Service and/or repair of your 425SX please contact your
local dealer.
Further information on HUMMINBIRD products can be found at:
www.humminbird.com