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Default Autopilot fails on Raytheon ST5000+ with "No Data" error

Advanced Compass Troubleshooting


After following the Autopilot compass calibration procedure to the letter
the autopilot will still not produce a deviation value. I am fairly
technical is there any advanced troubleshooting I can perform?


There are two instances that will cause the autopilot compass to not produce
a "deviation" value during the Sea Trial calibration procedure.

The first instance will be if the strength and characteristics of the
magnetic field around the compass is to high for the pilot to get through
the linearization procedure. Make sure that there is nothing around the
compass that would influence this field. This would include equipment
mounted on the other side of the compass bulkhead.

The second instance is a possible problem with the compass or the compass
wiring. You should try to "box" the compass to see if there is an obvious
problem. To "box" the compass put the pilot in STANDBY, next swing the
vessel a full 360 degrees. Even if the compass is out of phase (out of
calibration) you should see a nice smooth swing throughout the entire 360
degrees. A frozen compass heading indicates a problem with the compass
input. Double-check your connections. The autopilot will most likely give
the same frozen indication even if the compass was disconnected. If a
problem with the compass is indicated then this could either be due to the
compass, cable or compass circuit in the autopilot. The next step is to test
the fluxgate compass using the procedure below.

Raymarine Fluxgate Compass Test (Multi-meter required)

Multi-meter should be set to:

(a) Resistance scale

(b) 200 ohm scale

The following procedure should then be followed:

1. Disconnect the transducer from the system.

2. Connect one multi-meter lead to the red wire and the other lead to the
green wire and a reading

as indicated in the test data table should be present.

3. Follow the above procedure for all the color combinations indicated in
the test data table.

4. If all readings match those indicated assume the compass transducer is
functioning correctly.

Compass Test Data:

Cable Colors


Red to Green
4 ohms
Measurement is taken between the two colors

Red to Yellow
4 ohms
As above

Green to Yellow
8 ohms
As above

Screen to Blue
8 ohms
As above

All other combinations
Open Circuit

You are looking for a short or open. A +or - 2 Ohm reading is allowed.

If this check indicates a fault with the compass then you will be best
served by replacing the compass. If no problem is indicated then you should
send the compass and the course computer to a repair facility for

The text is from Raymarines hompage

Regards, TomS

"Donagh" wrote in message

Hello, I have a 38ft (11.5m) sailing cruiser with a Raytheon ST5000+
autopilot, Raytheon radar/chart plotter with Wind, Depth, Speed, GPS,
fluxgate compass, etc.
The autopilot works only when travelning west. Attempting to calibrate
the system always fails at the "Turn Boat" phase with a "Too Fast"
error even thou I've done the turn dozens of times exactly by the
book. The ST5000+ compass heading is wildly inaccurate. As the boat
turns the ST5000+ compass display jumps in large increments rather
than smoothly as I would expect.
Tying the autopilot in any direction other than West results in a
change of direction or a "No Data" error.
Any ideas?

Many thanks, Donagh.