How to Troubleshoot a Furuno Marine Radar

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Radar isn't consumer friendly since repairs that involve opening the cabinet of the unit or the scanner -- the rotating antenna -- or any change that can't be controlled by the knobs or switches on the front of the unit must be made by a federally licensed radar repair technician. In spite of that constraint, though, most radar problems are related to blown fuses, open circuit breakers or even a power switch in the wrong position.

Turn the radar unit on. If the unit fails to light up, check the fuses -- the location is marked in the radar owner/operator's guide; if these are in order, take the unit to a licensed radar technician. If the unit lights up, but fails to display an image, look at the scanner to ensure it's rotating.

Check the scanner for a blown fuse if the radar isn't rotating, then follow the wire from the scanner all the way to the radar -- if the scanner draws power from the radar -- to the circuit breaker. If the scanner doesn't draw power from the radar, check the scanner power switch to ensure it's in the "On" position. Set your multimeter to test for continuity. Place one probe of a multimeter on one post of the switch and the remaining probe on the other post of the switch and ensure the switch is viable; if so, call the tech. The problem is within the scanner antenna.

Turn the gain knob all the way to the right, clockwise. If the display doesn't show an image, take the unit to a licensed radar technician. If the display comes on but shows a "white screen" -- the screen is covered with interference -- turn the gain knob counterclockwise until images are suitable and little, if any, interference remains on the screen, and adjust the range.

Find a "target" that's visible visually and make sure it's visible on the radar. If not, turn the "Gain" knob or press the "Gain" control and the "+" side of the common turning bar until the object appears as a target on the radar.

Reduce the range (how) to 1/4 mile or less. Turn the "STC" control until there's a very small, fine scatter of "hash" at the centre of the screen

Raise the range (how) to 6 miles and turn the "FTC" knob until there's a barely discernible amount of interference on the screen.

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