Furuno 1720 Problem

[Dave47]

Hi all. I am experiencing some problems with my radar. After switching on, all seems ok but after a few seconds the display starts to revolve in an anti clockwise direction at about half to one degree per revolution of the antenna. This is when the boat is tied up to a marina berth, so the boat itself is not moving. Also the heading marker starts to flash after a few seconds of changing, for instance, the range. I do not use the radar very often, it came with the boat, and I sail mostly single handed, so I am a little reluctant to spend a lot of cash on what may turn out to be an expensive repair. I have tried adjusting the available controls behind the small panel, but nothing seems to cure the problem. Has anyone else experienced this type of problem? Dave47

 

[david_bagshaw]

It might me a bit of dirt in one of the slots in the reference unit.

in the scanner or display unit is a slotted disc that has an opto detector mounted to reference where the scanner is pointing, if there is dirt in a slot it might behave as you are experiencing. look out for the dead spider!

 

[Billjratt]

That sounds like the little sensor on the scanner which tells the scope when the scanner is pointing diectly forward (Ie, it's the sync between the two units) It's physically adjustable to allow accurate "dead-ahead " alignment.

However, it seems to be almost working, so I wouldn't climb up there just yet.
Is there a junction box somewhere, or does the cable between the units go direct with no joints? Check there first, then if necessary the joints in the radome which might have gone a bit foosty.

Other options include swapping the display with a friend to test the radome and wiring. Not sure but I think most models of that type/age will be compatible.

If you have access to an oscilloscope, you can check the stability of the pulse - book has all the pinouts.