Furuno FR-8051 manual Problem Check point and probable Remedy Cause

Problem	Check point and probable		Remedy
	cause
Adjust GAIN control	1.	IF amplifier	1.	Replace IF amplifier.
with A/C SEA control	2.	Signal cable between	2.	Check continuity and isolation of
set at minimum. Marks		antenna and display		coaxial cable. (Note: Disconnect the
and legends appear but	3.	Video Amplifier Circuit		plug and lugs at both ends of coaxial
no noise or echo.				cable before checking it by
				ohmmeter.)
			3.	Check video coax line for secure
				connection. If connection is good,
				replace SPU Board.
Marks, legends and	1.	Magnetron	1.	Check magnetron current.
noise appear but no	2.	Modulator Board		Replace magnetron.
echo. (Transmission	3.	Modulator SCR	2.	Replace Modulator Board.
leak, representing own	4.	SPU Board	3.	Replace SCR.
ship position, is				DANGER! - High Voltage
absent.)			4.	Replace SPU Board.
Picture not updated	1.	Bearing Signal Generator	1.	Check the connection of signal cable.
		Board (antenna unit)	2.	Replace SPU Board.
	2.	SPU Board	3.	Turn off and on radar.
	3.	Video lockup
Incorrect orientation of	1.	SPU Board	1.	The HDG readout shows xxx.x when
picture	2.	Gyro Interface		heading signal is not received.
			2.	Replace gyro interface.
TUNE control adjusted	1.	Deteriorated magnetron	1.	With radar transmitting on 48 mm
but poor sensitivity	2.	Detuned MIC		range, check magnetron
	3.	Dirt on radiator face		current. If current is below normal
	4.	Water ingress to the		value, magnetron may be
		waveguide or other feeder		defective. Replace magnetron.
		line.	2.	Check MIC detecting current. If it is
	5.	Second trace rejection is ON.		below normal value, MIC may have
				become detuned. MIC must be tuned.
			3.	Clean radiator surface.
			4.	Remove water from the feeder line.
			5.	Disable the second-trace rejector
				referring to paragraph 1.31.
Range changed but no	1.	Defective RANGE key	1.	Try to hit [+] and [-] RANGE keys
radar picture change	2.	SPU Board		several times. If unsuccessful,
	3.	Video lockup		replacement of keypad may be
				required.
			2.	Replace SPU Board.
			3.	Turn off and on radar.

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