ST6002 Autopilot issues

[danstanford]

I have owned the boat for 18 months and struggled to get this AP to work and have seen signs of hope but it has never worked properly. I have checked all the connections and replaced the battery in the flux gate compass but none of these things have worked. I tried to calibrate it by driving in circles as suggested and despite at least 30 mins driving in the biggest circle the boat would do, I would consistently end up with the too fast error after 10 minutes or so of dead slow motoring even dropping down into neutral when we turned down wind. All the other calibration settings were set ok including setting the correct course as noted by my chartplotter.
The issue is that the AP, when engaged, might stay inactive for a few minutes like we were on the correct course but then take a big crash turn off the course. In addition, the heading on the AP is way off the correct heading 40-100 degrees and after re-setting it correctly in the calibration process it will be way off again the next time the boat is started.
Is this likely to be the Flux Gate Compass or the ST6002?

Dan

[senormechanico]

My 4000 used to do that as well.
I never did figure out the "too fast" BS.
The reason at least for mine doing the quick off course thing was bad solder connections from the four power transistors mounted on a heat sink in the middle of the AP display circuit board.
It's not a particularly hard fix if you know how to solder.
On mine, EIGHT of the 12 connections were iffy.
It hasn't messed up since, unless we get hit with very close military radar.
Additionally, my HAM radio will also cause the same symptom when I transmit on certain bands, but at least I can be ready for that.

Mine keeps the heading memory ok so I've never looked hard to find any backup cell, but yours may have a small ni-cad cell inside which is going bad.

[Sailing Drummer]

I was having problems with mine. I disconnected everything and then reconnected it. That solved my problems. It might be worth a try?

[smac999]

Boat speed does not matter. Turning speed. Or rot. Is what matters. Normally a few mins per circle. Normally I'm doing maybe 1knot. Circle couple hundred feet round.

With twin engines I just put one forward and one reverse. Do circle in same spot. Circle size does not matter. Only thing that matters is compass is rotating at correct speed

If it's not working it maybe either in a bad spot, or you have a problem

[danstanford]

Originally Posted by senormechanico

Mine keeps the heading memory ok so I've never looked hard to find any backup cell, but yours may have a small ni-cad cell inside which is going bad.

Senor, do you mean the cell in the Flux Gate compass?
I have been struggling with thinking around the possible source/cause of this loss of heading in the AP. Could it be that the AP stores some adjusted value for the heading and then applies it to the Flux Gate Compass or does it only make sense that the compass somehow loses its settings? From a diagnostic perspective, my first thought was to replace the compass.
Dan

[senormechanico]

The cell, if you have one would be in the autopilot's display with all the other electronics.

There's nothing in my fluxgate but a gimbaled set of wires and coils.

[kcj]

Just went down this rabbit hole with my circa 2003 ray autopilot

First call ray tech support, they are very helpfull.

On mine first the rudder sensor went, then the control head. Replacing those bought me nine months.

When it started wandering off course (offshore ) last week, they said it’s either the flux gate compass or the brain, as it failed to recalibrate. Since both are on borrowed time, (they told me this nine months ago... ) I decided to bite the bullet and get a new one since I plan on owning the boat a stretch, and a failed ap is a major pita, especially since I functionally single hand.

Aside from the hole in my pocket I am glad I did it.

Ymmv

Cheers

[danstanford]

Originally Posted by senormechanico

The cell, if you have one would be in the autopilot's display with all the other electronics.

There's nothing in my fluxgate but a gimbaled set of wires and coils.

My flux gate compass did have a battery and I replaced it with high hopes. Once replaced, I thought I had it licked since it would respond to 10 degree shifts at the dock as expected but sure enough the next day on the water it went back to being drunk.
Mine is a 2007 model but certainly is newer than the one one my last boat which acted perfectly.
The rudder sensor does work perfectly though.

[senormechanico]

Mine's a 1995 model with no rudder sensor.