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Old 21-12-2007, 12:41   #1
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Alpha 3000 Autopilot Help Needed

Good Day Mates,
I have an Alpha 3000 autopilot that I have used for many years with no problems, until now. While sailing one day the unit refused to steer straight, it would steer hard right or hard left, but regardless of setting it would not hold a course. I have thoroughly checked all wiring and components with no improvement. Also I have changed out my control unit with my spare-same thing. Emails to Alpha marine are fruitless, they say its simple, I need to buy a new unit. My unit controls an hydraulic pump bridged into the main steering system. Turning the course knob will change the boat from hard right to hard left. External examination for the compass reveals nothing (no leaking fluid, damage, act,). I have found references on the web to similar problems, but alias, no solutions.
As I'm half way through a Caribbean loop and in Venezuela, shipping everything back (or even buying new components) is not a good option(pirates in the shipping companies, you know).
Thanks
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Old 21-12-2007, 12:58   #2
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Have you placed anything magnetic near the fluxgate compass?

Has Alpha mentioned checking the compass?

How about if you DO place something magnetic next to the compass, does the pilot try to change the heading?

My 3000 has worked fine for 18 years and the only weirdness was related to magnetic "things" being near the compass. It wouldn't steer properly.

I don't understand how you pilot turns the rudder post, but it is obviously able to push to hard over. If the control head and the spare perform the same it seems to NOT be there and must be the compass or the hydraulic ram.
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Old 21-12-2007, 13:12   #3
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defjef is exactly correct - it is most likely the fluxgate. And, he has a great idea on how to test it. You don't need a new system, but you might need a new fluxgate (they are very difficult to trouble shoot and/or repair).

Good luck,
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Old 22-12-2007, 06:02   #4
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Thanks for the replies, I am familiar with the magnet problem, but unfortunately that is not the problem, it started suddenly under way. I'll have to try the magnet test next time I'm underway. I was hoping someone had some insight on testing the fluxgate or it's attendant "black box". BTW, the autopilot powers a hydraulic pump that is bridged into main steering system. The AP heading control can be adjusted to turn the boat hard left or hard right, it just will not go straight. On a westerly course, with enough adjusting, the boat will correct through about 90 Deg. but will never settle down regardless of trim, yaw, or compass sensitivity adjustments.
Unfortunately I am in Venezuela and shipping parts is problematical.
Thanks All,
Ed
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Old 22-12-2007, 07:07   #5
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I don't have a clue about electronics, but I do have the 3000. I suspect that the problem DOES lie with the fluxgate as it generating "data" and it CAN be INTERMITTANT.

This is always hard to pin down.

The pilot NEEDS input from the fluxgate in order to stop "correcting" the course change.

If you want to proceed straight ahead the pilot needs to "know" what that heading is. If it has no input, setting a course to say 270° means nothing as it will cause the unit to HUNT looking for feedback from the fluxgate that it has reached the 270° so it swings back and forth full to port and then full to stbd.

This COULD be a problem PROCESSING the fluxgate input inside the control head, perhaps a failed cable from the fluxgate. But if you exchanged control heads it's rather unlikely that BOTH have the same fault. Assuming that since you did the swap and they BOTH perform identically, the problem lies OUTSIDE the control head that means cable to fluxgate or to the hydraulic ram. I believe that there is also a feedback from the ram and so the ram will be returned to center helm once the set course has been acheived.

For example if you are sailing accross a strong current the helm will not be at center helm to steer the course. But for the pilot to "know" that it will require feedback from the fluxgate and the ram (rudder). The pilot will put the hard over and ease it back to CL as it comes up to course, or in the case of small correction make small corrections.

You pilot is not able to hold a course because the feedback from either or both the ram (rudder) and the fluxgate. This sounds like it is in those units or in the cables to them.

Can Alpha give you and means to test the response by measuring the voltage at the pins of the connectors or the cables?

Just a guess.
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Old 22-12-2007, 07:31   #6
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One thing to try. On the back of the Alpha Control head, disconnect the flux gate wiring. Turn the Alpha on. The pilot should center the helm. If it does - the problem is in the compass. If it doesn't the problem is somewhere else.

If it is the compass, check for metal around the flux gate, magnets, etc. Also check that the compass is still intact and mounted properly (cover down, base up).

We also have an Alpha 3000 Our compass cover came off recently when it got whacked by something else in the locker. After cleaning up the oil - I called Chris and Alpha and he walked me through the process of replacing the oil and cover. Took less than an hour to fix it and get things working again (my Alpha compass is now protected with a recycled Yogurt container to protect from further clunks).

All the Alphas I've seen have an electric ram. Your's is different. Was this done by Alpha? Or did some one else come up with your setup? If the compass is OK, your problem may be in the control part of your hydraulic system.

I've found Alpha to be very reasonable to deal with if you call, talk to Chris and just be polite.

Good luck on your diagnosis and repair.

We'll be shoving off early tomorrow morning (900 Z) to head South down the Mexican Coast.

Regards,
Bill
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Old 22-12-2007, 07:34   #7
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Oops sorry, just drinking my coffee - I just noted the "no compass damage" comment in your original post...

Also, I also forgot to mention that my comment about heading off means I won't probably be on the net again until after the first of the year.
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Old 22-12-2007, 11:43   #8
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I am not familiar with this unit, so my advice may be incorrect. However, fluxgate compasses tend to all be very similar internaly. A delecate series of windings hanging on a yoke arrangement that can "woble" about inside the housing. this is so that yoke of windings will always remain horizontal no matter what the boat does. It has been known for some units to have that yoke jam. When the pilot failed, was the sea state smooth or ruff? If it was ruff, it is possible the yoke has over corrected itself and jammed up. I note that the replies suggest this one floats in oil. Make sure the oil has not slowly leaked out over time as the internals may not be "floating" properly.
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Old 22-12-2007, 12:45   #9
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Is the hydraulic pump run by electricity? If so, is there any possibility that it could have in the course of some other work done by you or others that it got hooked up with backwards polarity? If it was capable of pumping the opposite direction it would give you exactly the symptoms you describe.

Steve B.
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Old 06-01-2008, 20:20   #10
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I read somewhere, or was I dreaming?

This may be too late as the log date is a bit old.

I seem to remember reading in the install directions about "tuning" the fluxgate by driving the boat in a 360 degree circle to port and then again in a circle to starboard, which is supposed to re orient the fluxgate compass; especially if the unit has been "down" for a period of time. Perhaps someone else know of this.

Or am I just recalling a dream?

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Old 07-01-2008, 02:36   #11
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Flux Gate Compass Deviation (errors caused by shipboard environment) can be automatically corrected by swinging the boat over a full 360 degrees, or more (see your specific manual).

The usual correction method is the a constant rate turn (circle); and this rate should be in range 60 to 180 seconds for the full number of degrees specified (often 400 degrees, or 720 degrees).
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Old 15-09-2010, 18:30   #12
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Thanks to all,
It turned out to be be the winding in the fluxgate. As a last resort, I opened the unit up. Where the wire "flexed" between the top and the windings one of the wires had broken- I almost had it re-soldered before the whole thing went "in the ditch". A new unit fixed it. I guess 30 ears service is good enough.
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Old 15-09-2010, 18:49   #13
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Hi Zoomer... glad you got the problem fixed! For others who read this post, I had a good friend who purchased a Hans Christian 43 and, along with the previous owner, sailed from Morro Bay down to San Diego several years ago. They had to switch out steering all day and all night because every time they engaged the autopilot the boat just circled. Needless to say, were pretty tired when they pulled in to the marina in SD. After fighting his Alpha for several months, he asked me if I had any ideas. Upon checking the location of the flux gate we found that it was mounted conveniently behind a center bulkhead adjacent to his VHF. Problem easily solved by moving the fluxgate about 4 feet away from the radio and centerline in his boat. As electronics are added aboard, it is a good idea to check for interference from existing electrical and electronic gear... cheers, Capt Phil
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Old 16-09-2010, 10:34   #14
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Zoomer glad you were able to fix your Alpha 3000. I had one installed and sent it to be repaired three times and it would break after less then 24 hours of use. OUr final problem was on the Baja Ha Ha when it broke down after just three hours. I finally got so fed up I bought a new AP. I went with a WH Autopilot. It uses a lot more power then the Alpha but it is very robust. The main problem I am having with it now is being able to bleed it properly.
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Old 17-12-2010, 17:47   #15
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Hi Charlie

Do you still have any of the old parts from the Alpha auto pilot ? I have a 3000 and i need a compass.


thanks
Jack
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