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Jason, Marine Mechanic
Category: Marine Electronics
Satisfied Customers: 500
Experience:  Degree in Marine Technology, Also Certified with Mercury Marine, MCM, MIE, VP, Yamaha, Honda, Suzuki
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The image on the monitor of my model FCV-667 Sounder is

Customer Question

The image on the monitor of my model FCV-667 Sounder is reduced to approximately a 3 inch square. It appears all functions are working. Do you have a suggested diagnostic procedure to determine the cause?
Submitted: 2 months ago.
Category: Marine Electronics
Expert:  Russell H. replied 2 months ago.

Hi, thank you for contacting My name is Russell. I will do my best to provide the right answer to your question.

The look of your FCV-667 is that of a deep-profile, CRT-based display.

Given all I know about electronics, I advise you to at once, without delay, turn Off the FCV-667. It might be emitting UV radiation. If so, anyone's eyesight, that looks at it for long, is at hazard.

You see, when a CRT-based display gets smaller, it may be owing to an overvoltage of the anode on the CRT tube. Which in extreme cases, can cause UV emissions, or even X-rays in really severe cases. I doubt yours is a severe case. In fact, UV emissions or X-ray emissions from CRT-tubes when the circuitry behind them had severe errors, is a thing of the 1960s, and hopefully yours has been designed against such a possibility. But I wouldn't depend on it.

Now... if the same things are shown on the display that's left, just smaller, it is indeed an electronics malfunction requiring repairs. I don't doubt that for a minute.

Let me know... and let me know what you think. I'll advise you further. Thanks.

Customer: replied 2 months ago.
I have just put the boat in the water after storing if for about 6 months. When I turned it on, the image was fine but while traveling, it reduced in size. I charged the main batteries but they may not be fully charged. Would a lower charge cause this problem?
Customer: replied 2 months ago.
this is unsatisfactory. What is my charge?
Customer: replied 2 months ago.
Expert:  Russell H. replied 2 months ago.

A lower charge would not cause the problem. I don't think so. It might be caused by abnormally high voltage delivered to the screen anode, but it might also be owing to abnormally low voltage applied to the defector circuits that steer the electron beam in a CRT-tube-type display.

As for your charge: I have no power as a JustAnswer Expert over charges, pricing, billing, and that sort of thing. For concerns of that sort, you would need to contact Customer Support at, which may be reached at


What is the age of the Furuno FCV device in question?

May I advise you further on this case?

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