Eagle Fish ID 128 Installation And Operation Instructions Manual page 27

rejection feature. This can cause the unit to eliminate weaker signals such
as fish or even structure from the display. Try using resistor spark plugs or
routing the sonar unit's power and transducer cables away from other
electrical wiring on the boat.
No fish arches when the Fish ID feature is off:
1. Make certain transducer is pointing straight down. This is the most
common problem if a partial arch is displayed. See the Fish Arch section
in your owner's manual for more information.
2. The sensitivity may not be high enough. In order for the unit to display
a fish arch, it has to be able to receive the fish's echo from the time it enters
the cone until it leaves. If the sensitivity is not high enough, the unit displays
the fish only when it is in the center of the cone.
3. Use the Zoom feature. It is much easier to display fish arches when
zoomed in on a small range of water than a large one. For example, you
will have much better luck seeing fish arches with a 30 to 60 foot range than
a 0 to 60 foot range. This enlarges the targets, allowing the display to show
much more detail.
4. The boat must be moving at a slow trolling speed to see fish arches. If
the boat is motionless, fish stay in the cone, showing on the display as
straight horizontal lines.
ELECTRICAL NOISE
A major cause of sonar problems is electrical noise. This usually appears
on the sonar's display as random patterns of dots or lines. In severe cases,
it can completely cover the screen with black dots, or cause the unit
operate erratically, or not at all.
To eliminate or minimize the effects of electrical noise, first try to determine
the cause. With the boat at rest in the water, the first thing you should do
is turn all electrical equipment on the boat off. Make certain the engine is
off, also. Turn the unit on, then turn off ASP (Advanced Signal Processing).
There should be a steady bottom signal on the display. Now turn on each
piece of electrical equipment on the boat and view the effect on the sonar's
display. For example, turn on the bilge pump and view the sonar display
for noise. If no noise is present, turn the pump off, then turn on the VHF
radio and transmit. Keep doing this until all electrical equipment has been
turned on, their effect on the sonar display noted, then turned off.
If you find noise interference from an electrical instrument, trolling motor,
pump, or radio, try to isolate the problem. You can usually reroute the sonar
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