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arf145 10-06-2013 12:35 PM

Seatalk Cross Interference
I've got an interference problem among my new-to-me but 12-yr-old Raymarine instruments: ST60 wind, ST60 Tridata, ST4000+ autopilot. These are all powered by Seatalk connectors in this order: power comes into the ST4000+, then Seatalk to the Tridata, then Seatalk from the Tridata to the Wind.

The problem is between the autopilot and the wind instrument. Whenever the autopilot is driving the wheel, the wind direction moves as if in a trance and the windspeed becomes random. I've been out in 99 kt winds! On the other hand I've seen some evidence that the autopilot is also disturbed: it will keep a course but allow 10 degree swings while doing it sometimes.

I've isolated the drive cable for the drive part of the wheel pilot so it isn't running alongside any of the other cables, but this did nothing. I also see that someone put a ferrite core on the drive cable as it came out of the ST4000 control. This is Seatalk 1, so no termination is required on the last instrument, as I understand it.

Anyone have any ideas?

svinshallah 10-06-2013 03:07 PM

Re: Seatalk Cross Interference
First thing is to check ALL of the grounds associated with the system. Every one. Seatalk uses a common ground for -12V and the data ground. Bad grounds create noise on the Seatalk bus.

arf145 10-07-2013 10:50 AM

Re: Seatalk Cross Interference
I will definitely check the grounds, svinshalla. I believe I can picture a connection that should be redone. Thanks!

arf145 10-21-2013 11:37 PM

Re: Seatalk Cross Interference
Just an update on this: a check of the wiring inside our binnacle/steering housing showed a couple of suspect wires, so I re-crimped a couple of grounds and power leads. I had high hopes, but this did not fix the problem.

What did fix the problem was disconnecting the Seatalk 12 volt leads (red and black) coming into the ST4000+ controller and instead connecting separate non-Seatalk 12 volt leads. I got the power leads from those supplying my chartplotter. All is good now, with no apparent interference.

redline 10-29-2013 10:10 AM

Re: Seatalk Cross Interference
I would double-check the power supply to the autopilot; it may be seeing a drop when it drives the motor. Maybe not enough to affect its operation - yet, but if it was enough to bother the instruments, it's not right.

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