Raymarine AP ST4000 MKII

[Ken13559]

My 9 years old Raymarine Wheel Pilot ST4000 MKII with Rudder Ref Unit seems to be on it last leg. It hadn't gives me stellar performance all these years but is good enough. Now it wouldn't steer a proper course when set to Auto or Wind. Just wondering if it is the ST4000 Control Head problem or fluxgate or what? If it is fluxgate, it should steer well when on Wind mode ...right? If it is Rudder Ref problem, I checked its signal and it is proportional to steering movement. So that leaves the Control Head ...right?
Any advise?

 

[Don12364]

In 'Wind' mode it doesn't use the fluxgate to steer by but only uses it to warn if the wind has changed by more than a certain amount.
In 'Auto' it ignores the wind vane.
Yes, the Rudder Reference Unit should give a linear output depending on the position of the arm.
Noisy or interrupted signals from the RRU can play havoc so try monitoring the RRU output and gradually turning the steering and watch for jumps in the output voltage. An analogue meter is better than a digital one for this!

So; as it does not hold course on either 'Wind' or 'Auto', the area to suspect is the course computer AND ITS CONNECTIONS.
However most problems are the result of bad power supply or other inputs.
Not easy to diagnose though.
Good luck with yours.

 

[TomY]

Are you sure it's not the belt? My ST4000 stopped working well last season. I removed the belt. It wasn't broken, but I found an enlarged notch and kink in one spot. I found a replacement online. I haven't tried it out yet but I suspect it could be what it needs. It's 10 seasons old and has given better than I expected performance on my 38' yawl.

 

[Capt. Kermie]

I have the same model and it went haywire when I used a battery charger right above the fluxgate compass. Now I will have to go out and re-calibrate the compass and keep that charger off the boat. Could also be I have a battery cable crossing the compass path under the cabin sole somewhere, I'll have to investigate a bit further, but those are a couple possibilities.

 

[Ken13559]

I've replaced the belt 1-2 years back so I think its ok. Last change I made to electrical is to fit 2 computer fans driven by a 6W solar panel at the cowling air inlet to cabin which is above and slightly forward of where the fluxgate is. Fans are about 8-10 feet away from fluxgate (which is under the teak flooring ahead of engine) and solar panel is outside at forward hatch. I think this should not cause any issue ...I hope. No harm disconnecting the solar from fan to try and to check the wiring/connections of the at the control head and also the RRU.