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PAGE 32 491 INSTALLATION MANUAL Revision A
overview 11
safety considerations 11
troubleshooting 21
wiring 14
transducer
cautions 3, 5, 19
cavitation 5
hull thickness limits 6
noise problems 5
preferred mounting location 5
recommended incline angle 8
thru-hull installation with a fairing block 8
M
Maintenance, transducer 8
N
Northstar
feedback on manuals 25
website. See Website addresses
Northstar 491 Echo Sounder. See Echo sounder
Northstar 957/958 GPS/WAAS Chart Navigator 18
Northstar 957/958/6000i GPS/WAAS Chart Navigator 1
Northstar 961/962 GPS Chart Navigator 1
P
Parts, ordering. See Technical support
S
Safety considerations
491 11
transducer 3
Software upgrades, obtaining 18
Specifications 27
STAT (status) indicator light 18
T
Technical support
contacting Northstar 24
ordering parts 25
repairing the 491 25
repairing the transducer 25
Transducer
definition of 29
installation. See Installation, transducer
maintenance. See Maintenance, transducer
mounting. See Installation, transducer
recommended 4
service, parts and repair 25
Troubleshooting
diagnostics screen 21
flow chart 23
installation checklist 19
installation problems 21