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Old 29-12-2012, 16:18   #16
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Location: Colorado; Sailing Sea of Cortez
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Re: Raytheon Autopilot Questions


If you have a ST4000 PLUS (large screen), you must have a load (motor) attached to the motor terminals to test the output voltage. If not, you will see a short voltage spike and then it will fall off.

You can remove the motor wires from the head and connect the motor wires directly to 12 volts. That will tell you if the motor is OK.

On the ST4000 plus, "Low Batt" is almost always a problem inside the head and is caused by a variety of problems such as bad transistors / diodes / resistors...

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Old 30-12-2012, 09:33   #17
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Location: Galveston, TX
Boat: Block Island 40
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Re: Raytheon Autopilot Questions

Thanks guys,

I've followed all of the suggestions here. Tested voltage to the powerhead, clutch, etc.
Cleaned all connections, replaced questionable connections, connected the motor directly to 12v source (motor works).
My problem is most likely a prob with the control head based on what I've read here. I'm going to try to find a used one to get me by until I can get a monitor wind vane.
If dulcesuenos's offer is still good it looks like I'm also in the market for some nice cigars.

Thanks for all of the help. At a minimum I now know a lot more about my autopilot.
You guys rock.

Thanks again,


I have found that drinking rum in sufficient quantities will produce all the effects of intoxication....
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Old 30-12-2012, 10:15   #18
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Re: Raytheon Autopilot Questions

Originally Posted by flink View Post
Now there's a guy who can get sh*t done. That's good stuff. I'm not quite there yet but I'll make note of this guys solution, just-in-case....
Better just to have one of these in the spare parts onboard.

autohelm 4000 belt | eBay

Also, regarding bad connections in the control head, here's what I've done to repair mine.
It would occasionally turn hard to port or starboard for no apparent reason especially after a long time of use, then slowly go back on course if I didn't manually correct it.

The fix was resoldering nine out of a possible twelve bad connections to four power transistors in the head unit.
Each transistor has three leads. The transistors get warm during use and eventually the solder connections crack from stress.
The cracks are very small, but that's all it takes to give problems.
The transistors are all mounted around the middle of the board and are probably black in color.
Memento,homo, quia pulvis es, et in pulverem reverteris.
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Old 30-12-2012, 11:32   #19
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Offer still good, pm me your address info and well get her shipped, wont be till after the second when we get back to land.
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Old 05-01-2013, 01:07   #20
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Re: Raytheon Autopilot Questions

I have had issues with two ST4000 control heads. They absorb moisture and eventually will fail in various ways. You might try something that has worked for me several times. While on a 400 mile sail I placed the ST4000 control head in a dry plastic bag and let it sit in the sun for 1/2 day to drive the moisture out. Afterwards the unit worked well for a few days. After a few wet foggy evenings at sea it acted up again and again drying brought it back to life.
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Old 05-01-2013, 19:01   #21
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Re: Raytheon Autopilot Questions

I'm looking for a control head for the st4000 drive unit. I have'nt had any luck finding one but I did run across a flat rate repair service from Raymarine for $250.00 for the st4000 control head if it helps any. also if anyone has one to part with I would be interested in it good or bad.

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autopilot, raytheon

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