"Bruce in Alaska" wrote in message
...
In article ,
David Rinnan wrote:

Hi Jani,


Lost Bearing, bearing pulse error etc. sounds to me like loose
connection with the cable connecting transmitter and display unit. I
would check the cable connections inside the radome at first.

Secondly it could also refer to power outage at the transmitter, I
have
encountered this problem with both Raymarine and Simrad radars. Mostly
it occurs in sailing boats when battery level is getting lower but is
still enough to power the display. Only thing you get is the lost
bearing pulse which means that antenna is not rotating.

But back in to your case, with rough seas loose cables inside
connectors
can cause this problem. Try to pull each wire separately to see wheter
they come out, but better if there is warranty you can let others do
it.

/Jani

One thing to look at very closely, is the way the bearing information
is being generated in the Antenna Unit. In the 2nd and 3rd generation
Furuno Units, the antenna bearing information was generated by a
"Chopper Wheel" with an LED OptoPickup looking thru the Chopper Wheel
holes. This generated pulses, are equated to an angular rotation
of the the antenna.

If the seal leaked on these type units and some of the the Chopper Wheel
Holes filled with moisture, they wouldn't allow the LED InferRed Light
thru to the Pickup and pulses would be missed, and cause the Mechanical
Servo Motor that turned the Yoke coil to slow down and the picture would
rotate backwards.

On 4th and 5th Generation Radars, with Digital Displays, if the Pulse
Stream coming from the Antenna Unit is loosing pulses, the CPU that
Generates the display can't figure out how to display the receive data,
and has an Error Routine that does just what the OP discribes in his
second post. Hitting the "Clear Button" causes the CPU to wait for the
next "Heading Flash" and then start the routine that displays the
Radar Data, from Heading Flash, clockwise at the angular Pulse Rate of
the Bearing Pulses. Should some of those pulses come up missing, and the
next Heading Flash, not come with the right timing, then the CPU will
jump to the Display Error Routine again, and you start all over again.

Sometimes "Older" is better, and the old analog display would at least
give you a picture even if the display went backwards a few degrees per
revolution. Digital Displays can't do that, because of the way the
CPU has to display the data.

Look at the way the Bearing Data is generated, and look for missing
pulses in that system.

Bruce in alaska I know Old Chief Lynn has seen the above senerio....
--
Hey, Bruce, or when the "toilet bowl" filled with water, rust flakes falling
into holes in the encoder disk, or when the encoder disk was rubbing on the
optical pickup and filled some of the holes with a little black plastic
dust, or when the encoder wheel holes were round and were nearly impossible
to align with the optical pickup's beam...... oh, yeah, Bruce.... those
were the days when troubleshooting was easy money (not)!

Old Chief Lynn