Autohelm / Raymarine type 2 pump blowing fuses

[RobinNZ]

I have an Autohelm ST7000 withe a type 300 computer and type 2 hydraulic drive pump. Last night after a particularly boisterous trip down the east coast of NZ, the system blew the fuse on our main switch panel (not inside the computer). After popping a new fuse on and turning on the system, it starts up without any problem, but as soon as the computer tries to correct course from pressing +10, the motor runs for half a second then the fuse blows. I’ve tried removing the motor part from the pump part and it’s still blowing fuses when the hydraulic system is disconnected. I’ve also tried replacing the wiring between the computer and the motor, but that hasn’t helped either.

Has anyone got any input as to what could cause this problem? Can I overhaul the motor? Is it likely to be the computer?

Any help would be most appreciated - we’d love to get home for Christmas!

[smac999]

ideally you would have a clamp meter to measure the amps at the pump.

dissconnect the 2 wires from computer to pump. and try it. (obvisally it's not going to steer) if no fuses blow, then it's the pump. which is the most Likly. if fuse blows with no pump, then it's in the computer.

[RobinNZ]

Thanks for the suggestion! Actually, at the suggestion of a friend, I did something similar which was to create a small circuit with fuse holder, terminal block, switch and alligator clips to directly connect the motor to the battery. It’s still blowing fuses, so now I will pull the motor apart, clean and then reassemble. Hopefully that will be enough to get us home and then I can look at a replacement. At least it’s not the computer.