Furuno FR-1710 manual Advanced-level troubleshooting, Problem Check point Remedy Probable cause

Table 3-6 Advanced-level troubleshooting

Problem	Check point and		Remedy
	probable cause
Adjust GAIN control with A/C	1. IF amplifier		1. Replace IF amplifier.
SEA control set at minimum.	2.	Signal cable between	2.	Check continuity and isolation of
Marks and legends appear		antenna and display		coaxial cable. (Note: Disconnect
but no noise or echo.				the plug and lugs at both ends of
				coaxial cable before checking it
				by ohmmeter.)
	3.	Video Amplifier Board	3.	Check video coax line for secure
				connection. If connection is good,
				replace SPU Board.
Marks, legends and noise	1. Magnetron		1. Check magnetron current.
appear but no echo.	2.	Modulator Board	2.	Replace Modulator Board.
(Transmission leak,	3.	SPU Board	3.	Replace SPU Board.
representing own ship
position, is absent.)
Picture not updated	1. Bearing Signal Generator		1. Check the connection of signal
		Board (scanner unit)		cable.
	2.	SPU Board	2.	Replace SPU Board.
	3.	Video lockup	3.	Turn off and on radar.
Incorrect orientation of	1. SPU Board		1. The message "HD SIG
picture				MISSING" appears when the
				heading pulse is not received
				during stand-by.
	2.	Gyro Interface	2.	Replace gyro interface.
Tuning manually adjusted	1. Deteriorated magnetron		1. With radar transmitting on 48 nm
but poor sensitivity				range, check magnetron
				current. If current is below normal
				value, magnetron may be
				defective. Replace magnetron.
	2.	Detuned MIC	2.	Check MIC detecting current. If it
				is below normal value, MIC may
				have become detuned. MIC must
				be tuned.
	3.	Dirt on radiator face	3.	Clean radiator surface.
	4.	Second trace rejection is	4.	Disable the second-trace rejector
		ON.		referring to paragraph 1.33.
Range changed but radar	1. Defective RANGE key		1. Try to hit [+] and [-] RANGE
picture does not change				keys several times. If unsuccess-
				ful, replacement of keypad may
				be required.
	2.	SPU Board	2.	Replace SPU Board.
	3.	Mother Board	3.	Replace Mother Board.
	4.	Video lockup	4.	Turn off and on radar.

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