[C320-list] ST 4000 Autohelm autopilot

[Dave Ouimette]

My ST 4000 autopilot is not working properly and I'm hoping someone has a suggestion on how to get it repaired. Raymarine no longer repairs these older units. The primary symptom is the unit will not correct to starboard when the boat drifts off course; it will correct to port. The tech at Raymarine said this is a relatively common problem and reflects failure of a transistor in the head. My boat tech checked the voltage going to the wheel drive unit and, indeed, when a port correction is needed, the voltage is adequate (about 9.4 volts), but to starboard, the voltage is only .2 volts. Any ideas would be appreciated.
Dave
Hull 174