E38 original autopilot failing

EricFox

EricFox

Member II
I'm in the middle of a cruise on Lake Huron and my autopilot has decided to quit working. The ram is being driven (both ways), but the boat won't hold a course - just does big circles. My best guess is that something had failed in the compass or in one of the 2 brain boxes. I have done continuity checks on the 5 wires that go from the control box in the cockpit to the box that attaches to the compass - all good. And all of the other connections also appear to be good. I haven't yet opened up either of the boxes or the compass to look for any obvious faults - will do that tomorrow. I haven't yet found anything in any posts to suggest other possible causes. Any suggestions? Else I'll be spending the rest of my cruise at the helm :-(
 
David Grimm

David Grimm

E38-200
You say the ram is being driven both ways, did the arm come loose from the rudder post? My autopilot arm pinches the rudder post but is also through bolted with one bolt.
 
EricFox

EricFox

Member II
The unit is the old Alpha 3000. Everything is good mechanically - the thrust arm is engaging the tiller which is turning the rudder - I'm pretty sure it's something in the electronics.
 
Loren Beach

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
There are only a few older threads here, searching on 'alpha 3000 autopilot', but it is/was regarded as a good piece of gear. Best of luck to you to get yours going again.
 
EricFox

EricFox

Member II
I have returned from our summer cruise. I wasn't able to get the Alpha unit to work, however I had purchased a used Raymarine ST4000+ wheel drive knowing at some point the Alpha would probably bite the dust. I cajoled my son to drive it to us at one of our stops and installed it in a few hours. I have to say that I am very impressed with it - it tracks better than the Alpha, and ease of use is much much better. However it does give up slightly earlier than the Alpha as the waves build.

I haven't opened up the Alpha yet to try to identify what failed, and probably won't until winter (have to make the most of good sailing weather while we have it!). But I'm liking the Raymarine system enough that I may simply stick with it. And if anything, try to get it to drive the existing ram by building a drive board with higher curret drive (I don't expect that the Raymarine current drive is anywhere near sufficient to drive the ram), or perhaps re-use the drive circuitry in the Alpha. It looks like the only other mod I would need to make would be to the rudder sensor - absolute resistances in the Raymarine rudder sensor seeem to be higher than in the Alpha. If I go down this path I'll report back with progress.
 
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