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Configure 957 Aux Port for
the 490. See the 490
Operations Manual (GM490)
for instructions.
1. Check fuses and circuit
breakers.
2. Check power to 490 with
a voltmeter.
3. Verify that the data cable
between the 957 and
the 490 is properly wired
and connected.
The 490 and the 957 aren't
communicating properly.
Check the wiring of the data
cable between the 957 and
the 490.
490 INSTALLATION MANUAL, Revision B2
SECTION FOUR Troubleshooting and servicing the 490
No echoes displayed when STAR key is pressed.
Is the
Advance
Speed set to
zero?
Has
957 Aux Port
No
been configured
for the 490?
Check
Off
the 490's STAT
indicator
What
Once per
is the flash
Second
rate of the STAT
indicator?
Figure 12: 957/958 echo sounder system troubleshooting
Yes
Change the Advance Speed
setting.
No
Yes
1. Check transducer
connector for the
proper wiring.
Steady On
2. If wiring is correct,check
transducer impedance
with an ohmmeter.
3. If the transducer is open
or shorted, replace it
Flashing
Four Times
per Second
There's a hardware problem
with the 490.
Page 25
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