Jefa-Simrad Autopilot failure

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   I have bought this boat without a functioning Autopilot and know very little about why it hasn't work for many years, so I am trying find out whether it's a mechanical problem or a problem with the electronics. Now I'm a bit stuck and hope someone here could point me in the right direction. 
It is a Jefa DD1 with a Simrad AC12 computer, connected to a Simrad NSS8 and a Simrad AP24 display. 

When powering on the AP24 it tells me (translated from Norwegian) "remaining installation: Rudder test". 

When doing the rudder test we can hear the clutch engage, the motor turns 2 degrees, stops and the clutch disengage. When trying the same procedure and at the same time assist by turning the weel, the 15amp fuse in the computer blows (the fuse at the bottom left corner at the circuit board). The fuse on the wire to the motor is fine.

At the AP24 I do not get any error codes, it just stops as I do the Rudder test. Of course, when the fuse blows I get the alarm "No computer".    

I think I have ruled out that there is something wrong with the DD1 unit. It has been tested on the bench with a power supply meter. The motor runs perfectly fine, also with the clutch engaged, without consuming more than the power it is supposed to (max 2A). So nothing there that sould make the fuse to blow. 

The rudder feedback unit seems to work fine and shows the correct values. 

So any thoughts about what could be wrong or what tests I could do would be useful, thanks!

Hanse 400 2011

Edited by Astafari - 06 July 2024 at 11:44

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Astafari Members Profile Send Private Message Find Members Posts Add to Buddy List Sub Lieutenant Joined: 06 July 2024 Location: NO Status: Offline Points: 4	Post Options Post Reply Quote Astafari Report Post Thanks(0) Quote Reply Topic: Jefa-Simrad Autopilot failure Posted: 06 July 2024 at 11:40
	I have bought this boat without a functioning Autopilot and know very little about why it hasn't work for many years, so I am trying find out whether it's a mechanical problem or a problem with the electronics. Now I'm a bit stuck and hope someone here could point me in the right direction. It is a Jefa DD1 with a Simrad AC12 computer, connected to a Simrad NSS8 and a Simrad AP24 display. When powering on the AP24 it tells me (translated from Norwegian) "remaining installation: Rudder test". When doing the rudder test we can hear the clutch engage, the motor turns 2 degrees, stops and the clutch disengage. When trying the same procedure and at the same time assist by turning the weel, the 15amp fuse in the computer blows (the fuse at the bottom left corner at the circuit board). The fuse on the wire to the motor is fine. At the AP24 I do not get any error codes, it just stops as I do the Rudder test. Of course, when the fuse blows I get the alarm "No computer". I think I have ruled out that there is something wrong with the DD1 unit. It has been tested on the bench with a power supply meter. The motor runs perfectly fine, also with the clutch engaged, without consuming more than the power it is supposed to (max 2A). So nothing there that sould make the fuse to blow. The rudder feedback unit seems to work fine and shows the correct values. So any thoughts about what could be wrong or what tests I could do would be useful, thanks! Hanse 400 2011 Edited by Astafari - 06 July 2024 at 11:44

Astafari Members Profile Send Private Message Find Members Posts Add to Buddy List Sub Lieutenant Joined: 06 July 2024 Location: NO Status: Offline Points: 4	Post Options Post Reply Quote Astafari Report Post Thanks(0) Quote Reply Posted: 08 July 2024 at 12:15
	Update: I found out that the fuse blowed when the motor tried to run the other way. When swithing red and black wire on the computer output, the motor ran perfectly the other way, but the fuse blowed again when trying to run the other way. It was clearly that something was wrong with one of the outputs on the circuit board. This was confirmed when measuring the transistors. Circuit board was delivered to an electronics repairshop, which found a faulty mosfet. Now I'm waiting for them to get parts and get it fixed. Glad to have found an actual (and repairable) fault, closing in... Edited by Astafari - 08 July 2024 at 12:16

S&J Members Profile Send Private Message Find Members Posts Add to Buddy List Admiral Joined: 30 August 2014 Location: Perth WA / Med Status: Offline Points: 1371	Post Options Post Reply Quote S&J Report Post Thanks(0) Quote Reply Posted: 09 July 2024 at 15:02
	That is a great, if slightly concerning, result. Much less expensive than a new DD1!
	H458 #159 Primal Mediterranean cruising

Mark Pullen Members Profile Send Private Message Find Members Posts Add to Buddy List Commander Joined: 20 July 2022 Location: London, UK Status: Offline Points: 90	Post Options Post Reply Quote Mark Pullen Report Post Thanks(0) Quote Reply Posted: 25 July 2024 at 13:56
	Hi. If you’ve not already done so, I recommend contacting Jefa directly. They are extremely helpful and can help diagnose problems. Mine required a service and came back with most of the internal parts replaced. Try Lakhdeep - LS@jefa.com.
	Mark

Astafari Members Profile Send Private Message Find Members Posts Add to Buddy List Sub Lieutenant Joined: 06 July 2024 Location: NO Status: Offline Points: 4	Post Options Post Reply Quote Astafari Report Post Thanks(0) Quote Reply Posted: 26 July 2024 at 15:34
	New mosfet and transistor on the circuit board of the Simrad Autopilot computer solved the problem. Now it works perfect for the first time in more than 6 years (previous owner gave it up I think). The repair of the the circuit board cost me around $50(!) Yes Mark I have been in contact with Jefa directly to purchase a new direct link between the DD1 and rudder, the service was great! The above problem however was related to the Simrad electronics that controls the Jefa DD1, so not something Jefa deliveres.



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