GP1670F_1870F Operator's Manual - Furuno USA

12. MAINTENANCE, TROUBLESHOOTINGProblemThe speed indicationis not zero after theship is stopped.RemedySet [NAVIGATION SPEED] to [Low] in the [INTERNAL GPSSETUP] in the [SYSTEM] menu.Fish Finder TroubleshootingYou selected a fishfinder display, but nopicture appears.Marks and charactersappear, but nopicture appears.Picture appears butzero line does notappear.The picture sensitivityis too low.The depth indicationdoes not appear.Noise or interferenceshows on the display.• Check that the transducer cable is fastened.• Check if the fish finder source is correctly selected.Check that the transducer cable is connected.• The picture is shifted. Check the shift setting.• Check if [ZERO LINE REJECTION] in the [FISH FINDER]menu is off.• Check the gain setting in manual operation.• Check if marine life or air bubbles are on the transducer.• Bottom is too soft to return an acceptable echo.• For manual operation, adjust gain and range to display the bottomecho (in reddish-brown).• Adjust the bottom level.• Check if [DEPTH] in the [SELECT INPUT DEVICE] menu inthe [INTERFACE] menu is set to [Fish Finder].• Make sure the transducer cable is not near the engine.• Check the ground connection.• Check if another fish finder in the vicinity of your boat has thesame operating frequency as your fish finder.• Try to adjust the interference rejector.12-3