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HarrisonM · 08-09-2023, 09:38

I am working a case with B&G now for the NAC-3 autopilot, but thought I would check here.

All of a sudden my NAC-3 autopilot stopped working... I can see the rudder position on the chartplotter. I checked the connections and power with a multimeter and it all seems fine. I retried the "Dock Commissioning" and reset the port/starboard limits with no problem. When I do the rudder test it goes straight to fail. It is a straight fail like a setting could be wrong. I re-tested with the multimeter and as I do the rudder test I am not seeing voltage on the "DRIVE" or "DRIVE ENGAGE" connections.

When I called B&G they told me to check that the "degree/minute" setting and make sure it was 240. Double checked and it was fine. I need to call them back but last time I was on hold for 7 hours! Ugggg. Any suggestions/comments welcome...

Video of testing - https://share.icloud.com/photos/06ee...CGYzLhhw8_2KBA

HarrisonM · 09-09-2023, 11:42

I fixed it!!!!!!

The problem was with the "Alarm" lead connection. There is a lead on the motherboard so you can wire in an alarm or switch. I wired it to a switch. When the switch is in the "on" position the autopilot will not work. When I turn it "off" it works fine. I have a case open with B&G. I asked them what exactly this does and they said it is just an alarm. Obviously it does more.

Hope this helps anyone with this problem.

tanglewood · 12-09-2023, 12:56

Quote:

Originally Posted by HarrisonM

I fixed it!!!!!!

The problem was with the "Alarm" lead connection. There is a lead on the motherboard so you can wire in an alarm or switch. I wired it to a switch. When the switch is in the "on" position the autopilot will not work. When I turn it "off" it works fine. I have a case open with B&G. I asked them what exactly this does and they said it is just an alarm. Obviously it does more.

Hope this helps anyone with this problem.

Is that lead an input or an output? Most Alarm signals I have seen are outputs, so would never be wired to a switch. What do you intend the switch to do?

AKA-None · 13-09-2023, 18:30

Quote:

Originally Posted by tanglewood

Is that lead an input or an output? Most Alarm signals I have seen are outputs, so would never be wired to a switch. What do you intend the switch to do?

Short out the alarm output and shut the autopilot down?

stevead · 14-09-2023, 01:12

My money is on the switch being connected to the Mode input and not the Alarm output.

When the NAC-3 generates an alarm, it closes the circuit, thereby allowing the external relay to close and activate an external alarm light or audible alarm. It makes no sense to me that if the alarm circuit is closed that the NAC-3 would not operate.

AKA-None · 15-09-2023, 08:18

Doesn’t that driver for the relay have power supplied from the board? If so then shorting out that power source very well might shu the board down due to over current

stevead · 15-09-2023, 13:05

I would have presumed that the NAC-3 alarm outputs are connected to the coils of the relay and the contacts of the relay are connected to a power supply and the buzzers, alarm lights etc.

HarrisonM · 20-09-2023, 17:23

Thanks for all the replies. I figured it out. I am disappointed in B&G support. They never responded to my issue....

When the autopilot is engaged via a switch connected to the alarm you can disengage the autopilot and then re-engage it. That is what it does....

tanglewood · 20-09-2023, 18:41

Quote:

Originally Posted by HarrisonM

Thanks for all the replies. I figured it out. I am disappointed in B&G support. They never responded to my issue....

When the autopilot is engaged via a switch connected to the alarm you can disengage the autopilot and then re-engage it. That is what it does....

I think that's the Mode input, not the Alarm output.