[DG] [DG11] ST60+ wind system: inaccurate / unstable wind readings

[NorthernLight]

Dear all,

I have a problem with a ST60+ Wind system, which is installed in following configuration:
- ST60+ Wind head display; Raymarine Wind transducer at mast top, junction at mast bottom
- ST60+ Tridata (with speed, depth, temperature transducers)
- Seatalk to STNG adaptor
- ES75 MFD
- Raymarine Evolution Autopilot EV-200 / p70S
- Lowrance radio (NMEA2000 – STNG via spur cable)

The readings of the wind angle are altering very quickly and are not stable, even in moderate wind situations. The reading of the speed often gives too high values; I already tried with calibration, but without success. The problem occurred last year after installation of the autopilot, no idea if there are interferences between the different devices).

I performed the tests of voltage metering, as describes in the forum:

A) Voltages (DC) of ST60+ display head: (against shield, wind transduce not connected)
Red: 7,9V (normal value: 8V)
Blue / green: 0V
Yellow: 7,7V (is this OK?)

B) Voltages of wind transducer (only powered by 7,9V; ST60+ display not connected)
Red: 7,9V
Blue: 1,5 V … 5V (quickly altering) (desired value: 2V … 5.8V DC)
Green: 1,3 V … 2,6V (quickly altering) (desired value: 2V … 5.8V DC)
Yellow: 0,11 … 0,17V (not stable) (desired value: 0V … 5V DC)

C) Voltages of wind transducer; ST60+ display connected:
Red: 7,9V
Blue: 1,4 V … 1,8V (quickly altering)
Green: 2,0 V … 5,0V (quickly altering)
Yellow: 1,0 … 6,6V (not stable)

The wind transducer has been sent to and tested by Raymarine: no errors have been found.
It seems to be interesting, that the measured voltages significantly depend on the fact, if the transducer is connected (case C) or not connected (case B) to the ST60+ display. The wind had not changed very much during the time of the tests.

Does the a.m. voltage measuring indicate a failure at the ST60+ head display? Or the cable in the mast? What is your proposal for further checks to find out the reason for the malfunction?

Thanks in advance, kind regards,
Hans