Diagnosing ST4000 fluxgate compass malfunction

[mspanc]

Hello,

I own Autohelm ST4000 autopilot. For most of the time it works flawlessly but randomly it enters state as shown on this video: https://youtu.be/NlLIF-pTRKM

It seems to get randomly stuck to 081 bearing, which is nonsense as I am heading south when it happens and for most of the time it shows correct bearing.

Can you at least give me a hint what can be the cause or how to diagnose this? I checked cables and they seem to be properly mounted.

Thank you for support

 

[earlybird]

Try Raymarine FAQ, "Advanced Compass Troubleshooting", although the sticking might suggest something physically broken in the sensor. Can't recall if you can open it up easily though.
http://www.raymarine.com/knowledgebase/index.cfm?view=3798