[DG] [DG] Buzzing Noise Smartpilot S1

[cbarrer6]

Hi,
I have replaced my Raytheon type 100 course computer with a Smartpilot S1.
The old course computer broke down for second time, same transistor (IRFZ44N) failure. I prevents the clutch from engaging/disengaging.
My system is 12V and has a ST6002 control unit and a Lewmar DU130 Direct Drive connected via a linkage to the rudder axle.
I have to interchange the output cables to the drive (A&B) to make work.
The boat is a light displacement fin keel cruiser-racer (39ft, ca 8tons).
It works in normal conditions, but not on moderate swell or high wind.
But the thing that worries me is that as soon as I press Auto on the control unit starts a electrical buzz on the drive unit. Or so it seems, difficult to locate the exact point in the lazarette.
I never have this buzz with the type 100 course computer. So I wonder what could it be.

Thanks in advance for any help,

Carlos