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Page 64 491 Echo Sounder Operations Manual
Troubleshooting the echo sounder
Figure 9: Troubleshooting the echo sounder (961/962)
No echoes displayed when STAR key is pressed.
Is the
961/962
software
Version 3.0 or
greater?
Has
NMEA Port 3
been configured
for the 491?
Check
the 491's STAT
indicator
Is the
Advance
Speed set to
zero?
YES
YES
YES
NO
NO
NO
OFF
STEADY
GREEN
FLASHING
GREEN
RED
Contact Northstar Service to
upgrade to the latest version
of 961/962 software.
Change the Advance Speed
setting.
Configure NMEA Port 3 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 961/962 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 961/962
aren't communicating properly.
Check the wiring of the data
cable between the 961/962
and the 491.