Raymarine Auto-Pilot Linear Drive clutch stuck

[Tim Alden44]

Would appreciate any help on this topic. The clutch on my Raymarine auto-pilot linear drive (type 2) is stuck. Here are the symptoms

When the P70 control head is in standby mode, the wheel is very difficult to turn because the drive is engaged. If I change the control head to 'auto', I get an error saying no drive detected. If I turn the circuit breaker off for the auto-pilot, the clutch disengages and the wheel moves fine.

I've done a factory reset, I've updated the software and no change.

Any suggestions are appreciated.

 

[colemj]

Defender sells replacement clutches for those, as do other places. The clutch is pretty easy to access, as it is right behind the back cover.

It sounds like it is not fully engaging. Try putting 12V directly on the clutch wires at the unit. If it engages, then look to see if you have a resistance in your existing clutch wires from the AP unit to the drive unit.

Mark

 

[Tim Alden44]

Defender sells replacement clutches for those, as do other places. The clutch is pretty easy to access, as it is right behind the back cover.

It sounds like it is not fully engaging. Try putting 12V directly on the clutch wires at the unit. If it engages, then look to see if you have a resistance in your existing clutch wires from the AP unit to the drive unit.

Mark

Thank you. I will give that a try. I didn't realize that the clutch inside the drive unit was replaceable. Nice option

 

[Jan_H]

If the clutch disengages when the AP circuit breaker is turned off, then the problem isn't with the clutch, but more likely with the AP. The control head giving a no drive detected error when you set the P70 to Auto would seem to indicate a communication issue. You could try only having the P70 and AP talking to each other (disconnect the other devices) and see if that works.

 

[colemj]

The symptoms of increased friction in the steering when the AP is powered but not engaged, and the lack of friction when the AP is not powered, coupled with the AP not detecting drive movement when engaged, suggests the clutch is stuck halfway when powered - enough friction to feel it, but not enough to engage the drive.

This suggests either a bad clutch or a connection/wiring issue to the clutch. The latter can be tested by applying 12V directly to the clutch wire coming out of the drive unit.

Mark

 

[Tim Alden44]

The symptoms of increased friction in the steering when the AP is powered but not engaged, and the lack of friction when the AP is not powered, coupled with the AP not detecting drive movement when engaged, suggests the clutch is stuck halfway when powered - enough friction to feel it, but not enough to engage the drive.

This suggests either a bad clutch or a connection/wiring issue to the clutch. The latter can be tested by applying 12V directly to the clutch wire coming out of the drive unit.

Mark

Thank you. I will be at the boat later today and try this. Once I apply power to the clutch, I assume it should engage with power and disengage without power. If so, I suppose that means a bad connection. If neither of those happen, then I assume I need a new clutch?

 

[Tim Alden44]

If the clutch disengages when the AP circuit breaker is turned off, then the problem isn't with the clutch, but more likely with the AP. The control head giving a no drive detected error when you set the P70 to Auto would seem to indicate a communication issue. You could try only having the P70 and AP talking to each other (disconnect the other devices) and see if that works.

Thank you. What you say makes sense. I'm not sure how I would get the P70 to talk directly to the auto-pilot. I'll research, but any suggestions are welcome

 

[colemj]

Thank you. I will be at the boat later today and try this. Once I apply power to the clutch, I assume it should engage with power and disengage without power. If so, I suppose that means a bad connection. If neither of those happen, then I assume I need a new clutch?

That's right. If you apply power, and the clutch fully engages so that you can't move the wheel, then it is good and you should look for a high resistance in the wiring and connectors between the AP computer and the clutch wire to the drive unit. This is basically a single wire pair, but yours may have more connectors or joins in between.

I suppose if all of that checks out, then it could be a problem with the clutch circuit in the computer itself. This would be rarer.

Mark

 

[Jan_H]

I agree with @colemj - if you apply power to the clutch (with no power to the AP) then it should be very difficult to turn the wheel. However, when you put the P70 in standby, the clutch should disengage, just like what happens when the AP has no power. The clutch engaging when the P70 is in standby is indicative of a problem with the AP or with the communication. Had you changed/rewired anything on the network when this issue arose?
Jan

 

[Tim Alden44]

I agree with @colemj - if you apply power to the clutch (with no power to the AP) then it should be very difficult to turn the wheel. However, when you put the P70 in standby, the clutch should disengage, just like what happens when the AP has no power. The clutch engaging when the P70 is in standby is indicative of a problem with the AP or with the communication. Had you changed/rewired anything on the network when this issue arose?
Jan

thank you. No changes to the wiring at all. I was out sailing when this happened. The autopilot worked fine all day and only failed in our last hour.

I did some additional diagnosis just now. I removed the cover to the ACU400 and located the clutch output. With a multi-meter I got a reading of 14volts with the P70 in standby mode. This means the ACU is telling the clutch to engage. Raymarine has said to send them back the unit for testing and likely replacement. Not the answer I wanted, but this is the likely culprit. Unless I can find a way to factory reset the ACU - I will send it back.

I'll report back once complete. Thanks all