Furuno GP-7000F Operator's Manual page 118

11. MAINTENANCE & TROUBLESHOOTING
picture does not move although marks
and characters appear
zero line does not appear though the
picture appears
picture sensitivity is too low
the depth indication is not displayed
noise or interference shows on the
display
temperature of the water on the water
temperature graph is wrong.
11-4
Sounder troubleshooting
If ... Then ...
check if STOP is not selected at
PICTURE ADVANCE on the
SOUNDER menu.
check for loosened transducer
connector.
on SOUNDER SETUP menu, set
TRANSMISSION POWER to High.
the picture is shifted. Confirm shift
setting.
check gain setting, if using manual
operation.
marine life or air bubbles may be
clinging to transducer face.
on SOUNDER SETUP menu, set
TRANSMISSION POWER to High.
adjust gain and range to display the
bottom echo in reddish brown, if you
are using the manual operation.
if no noise appears after turning the
engine off, the engine interference is
suspected. Call your dealer.
check the ground.
other video sounder of the same
frequency as yours may be operating
near you.
check that sensor cable is tightly
fastened.