4. The
boat must be
moving
at
aslowtrolling
speed
to see fish arches. lithe 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
coverthe screen
with black
dots,
or cause the
unit
operate
erraticly,
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
your
Magna
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 onthe
bilgepumpandviewthesonardisplayfornoise.
If no noise is
present,
turn the
pump
off,
then turn on the VHF radio andtransmit.
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
re-route
the sonar unit's
power
cable and transducer cable
away
from the
wiring
that is
causing
the
interference.
VHF radio antenna
cables radiate noise when
transmitting,
so
be
certain to
keep
the sonar's wires
away
from it. You
may
need to route the sonar
unit's
powercable
directlyto
the
battery
to isolate
it from
otherwiring
on the boat.
If
no noise
displays
on the sonar unit from
electrical
equipment,
then make
certain
everything exdept
the sonar unit is turned
off,
then start the
engine.
Increase the RPM with the
gearshift
in neutral. If noise
appears
on the
display,
the
problem
could be one of three
things;
spark plugs,
alternator,
ortachometer
wiring. Try using resistorspark plugs,
alternatorfilters,
or
routing
the sonar unit's
power
cable
away
from
engine wiring. Again,
routing
the
power
cable
directly
to
the
battery helps
eliminate noise
problems.
Make certain to
use the in-line fuse
supplied
with the unit when
wiring
the
power
cable to the
battery.
When no noise
appears
on the sonar unit after all of the
above
tests,
then the
noise
source is
probably
cavitation.
Many
novices or
persons
with limited
experience
make
hasty
sonar installations which function
perfectly
in
shallow
water,
orwhen the
boat is at rest. In
nearly
all
cases,
the cause of the
malfunction
will be the location
and/or
angle
of the transducer.
The face of the transducer
must
be
placed
in a location that has a smooth flow of water
at all boat
speeds.
Read
yourtransducer
owners manual for the
best
mounting
position.
26
TABLE OF CONTENTS
INTRODUCTION
INSTALLATION
1
POWER CONNECTIONS
2
SPEED/TEMPERATURE SENSOR
3
KEYBOARD BASICS
4
DISPLAY
5
MENUS
5
OPERATION
6
AUTOMATIC
6
RANGE
6
ZOOM
-
Automatic
Operation
7
ZOOM
-
Manual
Operation
8
SENSITIVITY
9
GRAYLINE®
9
FISH ID
10
cHART5PEED
11
DISPLAY MODE
12
ALARMS
14
FISH ALARM
14
DEPTH ALARM
15
LAMP
16
FEET/METER
16
DISPLAy CONTRAST
16
ASP
(Advanced Signal Processing)
17
TRANSDUCERS AND CONE ANGLES
18
SIGNAL INTERPRETATION
19
FISH ARCHES
20
WATER TEMPERATURE
AND THERMOCLINES
21
SURVEYINGALAKE
23
BAIT FISH
23
SONAR TROUBLESHOOTING
24
HOW TO OBTAIN
SERVICE
27
Copyright
©
1990,
Eagle
Electronics
All
rights
reserved.
All features and
specifications
subject
to
change
without notice.
All screens
in
this
manual are simulated.
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