Simrad AC42 turns to port but not starboard

[ArranP]

Recently replaced the AC42 autopilot unit.

The new unit is turning to port but not starboard.

Disconnected the RPU300 pump and connected AC42 drive unit terminals with voltmeter to measure voltage.

Put AC42 into Virtual Rudder Feedback mode by deselecting the RF25 Rudder unit in source list.

Ran Autopilot -> Installation -> Rudder -> VRF calibration

Commanding rudder to turn to port and starboard in NFU mode.

Getting voltage when to port but not to starboard in both VRF calibration and NFU mode. Is this a failure of the AC42 unit ?

Tried with both 12v and 24v setting, and motor output is set to Max.

Thanks for feedback in troubleshooting this problem.

Regards
Arran

[tanglewood]

Are you measuring voltage right at the AC42 terminals, or at the pump? Check right at the AC42.

I don’t recall, but check for fuses inside the AC42.

[SailingHarmonie]

My recollection is the RPU300 is a two wire drive unit, where the voltages reverses to turn in the opposite direction.

So everything, wires, connections, fuses, etc, external to the AC42 is identical when driving the rudder left or right. Seems to me the problem must be inside the AC42. A call to tech service is indicated. I had a similar issue with a new unit, and they shipped a warranty replacement the same day.

[ArranP]

Originally Posted by tanglewood

Are you measuring voltage right at the AC42 terminals, or at the pump? Check right at the AC42.

I don’t recall, but check for fuses inside the AC42.

Voltage is being measured at the AC42 drive unit terminals.

There is just 1 fuse on the AC42.

[ArranP]

Originally Posted by SailingHarmonie

My recollection is the RPU300 is a two wire drive unit, where the voltages reverses to turn in the opposite direction.

So everything, wires, connections, fuses, etc, external to the AC42 is identical when driving the rudder left or right. Seems to me the problem must be inside the AC42. A call to tech service is indicated. I had a similar issue with a new unit, and they shipped a warranty replacement the same day.

My thoughts also.

[smac999]

sounds like the ac42 is dead.

you can also feed plus and minus 12v direct to pump and see if it moves both ways. if it does then more points towards ac42.

it could be a pump that only moves 1 way but then you'd have voltage at the unit

[ArranP]

Originally Posted by smac999

sounds like the ac42 is dead.

you can also feed plus and minus 12v direct to pump and see if it moves both ways. if it does then more points towards ac42.

it could be a pump that only moves 1 way but then you'd have voltage at the unit

Yes, done that, pump moves both ways.

[smac999]

Originally Posted by ArranP

Yes, done that, pump moves both ways.

You should check the current draw as well. It’s possible the pump is drawing very high current. Which killed the ac42. And would just kill the next one too.

I trouble shooted a dead raymarine doing the same thing a few weeks back. Only voltage 1 way. But testing the small pump direct to 13v it was moving but I was getting like 17a draw at dock which is really high. . (Would be higher under rudder load). So Likly the pump killed his computer. And both need changing.