Autohelm 6000 relay problem

[svenkei]

Dear cruisers,

I just finished crossing the Golf of Biscay to A Coruna Spain and found myself with a malfunctioning autopilot on the first day of the crossing.

I have a rather old Autohelm 6000 with a rotary drive for my 18 ton steel ketch.
It has worked flawlessly for may years until now.

The unit turns on and correctly displays magnetic heading. As soon as I engage the autopilot by pressing "auto" there is a high pitch buzzing sound coming from the course computer. I openend up the unit and located the source of the buzzing to be one of three high capacity relays on the circuit board. Most likely relay 1 (RL1), see picture.

It seems like the relay is not engaging meaning clutch and motor will not turn on. The component and the boards in general still look pristine. No oxidation, burned parts or visible damage what so ever.

Does anyone have an idea what might be going on here and of course how to fix.

Thanks and regards,

Marc

[deblen]

Which of 3 relays are chattering? Visually check contacts of relay(s) for "burning".



This may help diagnose,if you have electronics knowledge.
https://sbo.sailboatowners.com/downl...__15317164.pdf


You could remove the 4 drive slide on wires from relay board & apply direct 12V & 0v to wires to manually operate the mechanical drive & clutch-if you know what you are doing.(No offence intended-but you could do expensive damage if you don't know)
Safest solution is a marine tech.

[svenkei]

Hi delen,

It is RL1, de right most relay. Visual inspection of this or other components show no signs of burning what so ever.

Thanks for the link, I also found it and went over it. I don't feel comfortable in bypassing circuitry. This should just work.

Perhaps the relay is faulty and replacing it solves the issue but the root cause might also be somewhere else. I am not that technically inclined to trouble shoot it unfortunately.

[Joh.Ghurt]

These boards are quite easy to fixe by someone familiar with a soldering iron and an oscilloscope. You should also find replacement relays on mouser or aliexpress if needed.

However it’s hard to do any useful diagnosing remotely. Your best guess is to find an aging radio- or tv-tech to take a look at it. Or ask around the marina, if any yachtie happens to be one.

[svenkei]

Thank's all for your suggestions and help. I continued down the trouble shooting rabbit-hole and found the problem .... it is embarrassingly simple.

I have a dedicated switch for the autopilot which directly feeds the course computer and an external relay that enables the high power connection for the autopilot motor. That relay appears not to work so the motor connection on the course computer never receives power. The relay is fused and I decided to check the fuse. Fuse was OK, but refitting it in its fuse holder restored connection, relay tripped, Autohelm started working!

So nothing but a faulty connection not related to the Autohelm itself. Valuable lesson here, first check all connection in the system before thinking it may be the electronics themselves that are faulty.

Glad it worked again.