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Raymarine s3g ast / st7002 / linear autopilot failure


Scott SV Tengah
 

Hi all, 
 
We just had our raymarine linear autopilot with the sg3 ast computer fail after working flawlessly for our entire ownership. 
 
The error on the head unit raymarine st7002 says "Drive stopped". 
 
The sg3 ast supply is at 26.8v and the clutch is correctly set at 12v and gets around 12.48v
 
What I do notice is that the voltage at the computer motor output and consequently the linear drive is only 13.4v
 
I checked all raymarine computer fuses and cleaned the fuse contacts to no avail. 
 
Has anyone experienced a failure like this or have any idea what I should check? 
 
 
--
Scott 
2007 A54 #69
SV Tengah
http://www.svtengah.com


 

I had a failure of the Raymarine TYPE 2 Linear drive. It was the clutch that failed. The message was not drivestop.
From the SG# Manual - DRIVESTOP  error:
The autopilot is unable to turn the rudder (this occurs if the weather load on helm is too high, or if the rudder position sensor has passed beyond the preset rudder limits or rudder end-stops). Check drive and rudder position sensor. Check the drive wiring is correctly connected.

That voltage for the motor output is low, but maybe it is low because of resistance in the motor...check with the motor disconnected. 

Maybe a failure of the SG3.

Do you have a spare? Dan Gerhardt <C250@...> can repair SG3.

Bill
CW Bill Rouse Amel Owners Yacht School
Address: 720 Winnie, Galveston Island, Texas 77550 
View My Training Calendar


On Tue, Sep 15, 2020 at 3:13 PM Scott SV Tengah <Scott.nguyen@...> wrote:
Hi all, 
 
We just had our raymarine linear autopilot with the sg3 ast computer fail after working flawlessly for our entire ownership. 
 
The error on the head unit raymarine st7002 says "Drive stopped". 
 
The sg3 ast supply is at 26.8v and the clutch is correctly set at 12v and gets around 12.48v
 
What I do notice is that the voltage at the computer motor output and consequently the linear drive is only 13.4v
 
I checked all raymarine computer fuses and cleaned the fuse contacts to no avail. 
 
Has anyone experienced a failure like this or have any idea what I should check? 
 
 
--
Scott 
2007 A54 #69
SV Tengah
http://www.svtengah.com


Scott SV Tengah
 

It turns out the problem was carbon buildup on the brushes. We have put 20k nm and I am guessing the previous owners logged at least 10k nm on the unit.

Anyone have any luck finding replacement brushes for Raymarine Type 2 linear drive?

My understanding is that the brushes are: Morganite Electrical Carbon 6x10x20mm, grade CM9/M50-5113.  Or for those on imperial...0.24x0.39x0.79inches. I believe that's for the 12v model, but perhaps the brushes are the same? 
--
Scott 
2007 A54 #69
SV Tengah
http://www.svtengah.com