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491 Echo Sounder Operations Manual Page 65
Figure 10: Troubleshooting the echo sounder (957/958)
Checking the transducer
To provide the best possible performance with the 491 echo
sounder, Northstar recommends the use of an Airmar
No echoes displayed on sounder screen.
Has the
navigatorʼs
Aux Port been
configured
for the
491?
Check
the 491's STAT
indicator
Is the
Advance
Speed set to
zero?
YES
NO
YES
NO
OFF
STEADY
GREEN
Change the Advance Speed
setting.
Configure the navigatorʼs
Aux Port for the 491. See
Section 1 of this manual
for instructions.
1. Check fuses and circuit
breakers.
2. Check power to 491 with
a voltmeter.
3. Verify that the data cable
between the navigator and
the 491 is properly wired
and connected.
491 is communicating with
the navigator.
1. Check transducer
connector for the
proper wiring.
2. If wiring is correct,check
transducer impedance
with an ohmmeter.
3. If the transducer is open
or shorted, replace it
There's a hardware problem
with the 491.
The 491 and the navigator
aren't communicating properly.
Check the wiring of the data
cable between the navigator
and the 491.
FLASHING
GREEN
RED