Radar gone Phut

[MarkJohnson12345]

Ref an earlier post of mine about a Furuno 1722 radar that was just showing concentric rings on the screen, fault has now been found.

To add to the knowledge base, the problem was that the belt that turns the scanner had come off the motor.

Thus the radar was working but only pointing in one direction. I have spoken to Jim at Furuno who was very helpful, he said that the scanner must have stopped over the magnetic block that detects the scanner rotation. If it had stopped elsewhere an error message would have been generated.

Only reason that the belt could have slipped off was that the motor/cog that drives the belt to the scanner might have slipped a little. Its fixed by a grub/ alan screw that is normally rock tight.

So good news, just off back up the mast......................

 

[ShipsWoofy]

[ QUOTE ]
Thus the radar was working but only pointing in one direction. I have spoken to Jim at Furuno who was very helpful, he said that the scanner must have stopped over the magnetic block that detects the scanner rotation. If it had stopped elsewhere an error message would have been generated.

[/ QUOTE ]

Interesting scenario and very interesting symptoms shown on the screen from this fault.

When I first fitted my raymarine I diligently attached the string supplied to give a safety to the dome cover. Because I fitted it on the ground (mast stepped) the string managed to fall to a position where the antenna caught it during rotation.

I got an immediate 'Scanner Not Rotating' error message. Had it done the same as yours and stopped over the sensor then it would have been a real nightmare to solve.

Sorry to send you on a bum steer in the other thread, I will hopefully be able to remember the details of your fault for the future if I am ever trying to help someone else.

 

[MarkJohnson12345]

Apologies are not required.

Just very grateful for your time and thoughts.

Also important to pool this information.

regards

 

[Billjratt]

for general info - older radars don't know the scanner isn't turning, they just display the current static blips all round the 'scope. I've been caught by the wee (disable scan motor) switch at the back of a Furuno 1730, which wasn't mentioned in the circuit diagram!

 

[Omatako]

Hi Mark

See my other submission under the string dealing with sutable location of radar.

I always wondered whether this was a typical Furuno problem and made a decision not to test it by buying Furuno again. Now I am a little further convinced that it is at least reasonably typical if not common. My unit was a 1622 circa 2004.

It's a little difficult to rationalise my belief when one thinks of the squillion other Furuno units in service. One would believe that if it was common there would have long since been a Furuno fix for it. But two posts in one week with similar problems? Hmmm. . . . . Gratefully, I no longer own that boat.

And hopefully you are not at sea when it happens next (and I believe it will). It's a lot more difficult to fix when you're screaming through a 5 metre arc.

 

[MarkJohnson12345]

More we share info the better.

Thats three radar's with the same problem. Just 3 out 1000's or are there more out there??

I must think the manufacturers have spent a lot od time on this potential problem.

I was watching my radar when it went phut, I can only think it was because I was ashore in a cradle, rather than in the water with the cushioning effect of the sea. The vibration of wind on the mast may have caused the belt to jump.

If so, what other effects do these high winds have on masts etc when our boats are ashore??

Rgds

 

[DaveS]

Wind on mast

I would worry about the effects of strong winds on the mast of a boat propped up ashore. Judging from the pictures of the boats in the south of England that blew over last month, they all appeared to have been left with their masts up. In many marinas (including mine) leaving the mast up over winter ashore is not allowed - perhaps for good reason?

 

[MarkJohnson12345]

Re: Wind on mast

Interesting point.

My 2nd boat bought from the Hamble was in the yard with the mast down. Was a good opportunity ti inspect the mast.

Here in Swansea very few take down masts to overwinter on the hard.

MJ

 

[Omatako]

Re: Wind on mast

Getting back to the radar, however, falling off the back of a ten-foot wave can't really be construed as a cushioned effect and the effect is severely muliplied when the device is 6 or 7 metres up the mast. If the belt is going to jump it'll do it then.

Mine did it several times, never on land.

 

[MarkJohnson12345]

Re: Wind on mast

Accepted. Just trying to work out why it did it.

Furuno at the LIBS had no idea.

Sympathetic tho (no use at akk)

MJ

 

[Billjratt]

Re: Wind on mast

The old scanners had gears - no belt. Maybe we've unearthed a cost -saver that shouldn't be allowed out. Furuno do have a "speak to me " on their site. Maybe you 'belters' should open the jar of worms...

 

[hightech]

Re: Wind on mast

Belts were introduced for a number of reasons by most manufacturers for a number of reasons.

Quieter in operation
Need less alignment than gears
Cheaper to fix and manufacture
reduces shock loading to the motor

Geoff