No autopilot computer

[ringo]

Hi !

Need assistance on my zues 3 chartplotter. It doesn't seem to be able to connect my B&G NAC-3 Autopilot and it keeps showing "no autopilot computer" on my Zues 3 display. They are both connected on a nmea2k network. Have tried restarting the system, disconnecting and connecting the NAC-3. Any ideas what i can do ?

[Rucksta]

On my Zeus that message means the NAC 3 is not receiving hi current power.

Inside the NAC 3 is a 30 amp fuse.
2 power feeds low current via network hi current separate switched supply.
Polarity sensitive with on board polarity checker.
Ensure earth - ground not negative - is connected prior to powering on.
HF ground strap can be utilised .

[ringo]

Originally Posted by Rucksta

On my Zeus that message means the NAC 3 is not receiving hi current power.

Inside the NAC 3 is a 30 amp fuse.
2 power feeds low current via network hi current separate switched supply.
Polarity sensitive with on board polarity checker.
Ensure earth - ground not negative - is connected prior to powering on.
HF ground strap can be utilised .

Thanks for the reply !

Is it possible to use a multimeter to check on the NAC straight to see if it's being supplied enough power ?
Sorry able to explain this " Ensure earth - ground not negative " statement ?

[Rucksta]

Under the removable cover on the NAC 3 there are a series of terminals .
On the left is the hi current + & -.
There is also a ground.
I run the ground to the HF radio ground strap.
The + & - are wired to the battery with cable suitable for 50 amps.
A 50 amp circuit breaker runs inline.

Under the cover are outputs for the DC feed to the AP actuator (ram) and peripheral connections for relays or other switching arrangements to feed the actuator along with the NMEA connectors wired to Molex plugs not B&G network plugs you may be familiar with.

Also under the cover are L.E.Ds that display a seld check procedss on commissioning.

Check the B&G website for the installation manual for the NAC 3.
It's mainly visual and covers multiple scenarios.
Choose the simplest that most closely matches yours and follow the commissioning procedure outlined.

Im theorising as I am not and eletrical engineer but the reason for the ground connection is you have two DC volt supplies to the NAC unit (network voltage and drive voltage. The ground strap may be to eliminate capacitance caused by a variation in potential from the two sources.

B&G go to some length to highlight the need for the ground connection to be the first connection made.

Mine draws between 0.25 & 5 amps under normal operation averaging about 1.5.

I can measure the current draw with a clamp meter when it is operational.
I don't know how you would measure a current draw when it is non operational


Not sure if your unit has ever worked. i.e. is this a fault or and installation error.

Check the manual and follow the install / commissioning process and start to trouble shoot from there.


If the manual is followed and you still have a problem B&G offer excellent phone support (in my part of the world) with an extensive dealer network.


B&G is sensitive to software version and updates are best done sequentially i.e. don't skip an update.

My experience is anything that can't be fixed over the phone gets shipped and a warranty replacement supplied.(even for items out of warranty.

[ringo]

Originally Posted by Rucksta

Under the removable cover on the NAC 3 there are a series of terminals .
On the left is the hi current + & -.
There is also a ground.
I run the ground to the HF radio ground strap.
The + & - are wired to the battery with cable suitable for 50 amps.
A 50 amp circuit breaker runs inline.

Under the cover are outputs for the DC feed to the AP actuator (ram) and peripheral connections for relays or other switching arrangements to feed the actuator along with the NMEA connectors wired to Molex plugs not B&G network plugs you may be familiar with.

Also under the cover are L.E.Ds that display a seld check procedss on commissioning.

Check the B&G website for the installation manual for the NAC 3.
It's mainly visual and covers multiple scenarios.
Choose the simplest that most closely matches yours and follow the commissioning procedure outlined.

Im theorising as I am not and eletrical engineer but the reason for the ground connection is you have two DC volt supplies to the NAC unit (network voltage and drive voltage. The ground strap may be to eliminate capacitance caused by a variation in potential from the two sources.

B&G go to some length to highlight the need for the ground connection to be the first connection made.

Mine draws between 0.25 & 5 amps under normal operation averaging about 1.5.

I can measure the current draw with a clamp meter when it is operational.
I don't know how you would measure a current draw when it is non operational


Not sure if your unit has ever worked. i.e. is this a fault or and installation error.

Check the manual and follow the install / commissioning process and start to trouble shoot from there.


If the manual is followed and you still have a problem B&G offer excellent phone support (in my part of the world) with an extensive dealer network.


B&G is sensitive to software version and updates are best done sequentially i.e. don't skip an update.

My experience is anything that can't be fixed over the phone gets shipped and a warranty replacement supplied.(even for items out of warranty.

It used to work so i think it’s probably a fault and not an installation error however I’m unable to do any updates as it isn’t showing on the zues or triton display.. do i measure the current draw across the whole unit ?

[Rucksta]

The NAC 3 needs two power supplies
Low current 12V to run the brains.
This is delivered via the NMEA network cable.
High Current 12V runs the muscle.
High current is delivered via separate connection user provided.
The output is switched by solid state devices to power the actuator often by polarity change.

The error message "No AP computer available" means the unit is no powered up.
Most common cause is High currrent feed disconnect e.g. breaker switch.
The message could also be caused by no low current feed over the network.

On the Zeus unit drill down through network menu to list devices.
If the NAC 3 is listed it waas present at some stage.
Refrresh the devices page
If the NAC 3 vanishes it is no longer chirping on the network.
This means it either not getting low current power or it is not able to send the chirp back over the network - cabling connection fault.

If your other instruments are working i.e. Triton trace the dropper from the NAC back to where the Triton & NAC share the backbone.
If the fault is network it will lie between this junction and the unit.

Some of the abouve steps my be in areas with poor access
The NAC diagnostics with on board LED illumination sequences .

The manual outlines the sequencing.


Time to start crawling around and try these tests.

[ringo]

Originally Posted by Rucksta

The NAC 3 needs two power supplies
Low current 12V to run the brains.
This is delivered via the NMEA network cable.
High Current 12V runs the muscle.
High current is delivered via separate connection user provided.
The output is switched by solid state devices to power the actuator often by polarity change.

The error message "No AP computer available" means the unit is no powered up.
Most common cause is High currrent feed disconnect e.g. breaker switch.
The message could also be caused by no low current feed over the network.

On the Zeus unit drill down through network menu to list devices.
If the NAC 3 is listed it waas present at some stage.
Refrresh the devices page
If the NAC 3 vanishes it is no longer chirping on the network.
This means it either not getting low current power or it is not able to send the chirp back over the network - cabling connection fault.

If your other instruments are working i.e. Triton trace the dropper from the NAC back to where the Triton & NAC share the backbone.
If the fault is network it will lie between this junction and the unit.

Some of the abouve steps my be in areas with poor access
The NAC diagnostics with on board LED illumination sequences .

The manual outlines the sequencing.


Time to start crawling around and try these tests.

Got it ! will give it a go! Sorry, am very new to this

Thanks so much !

[Rucksta]

Originally Posted by ringo

Got it ! will give it a go! Sorry, am very new to this

Thanks so much !

Let us know how you go - soon you will be expert.

P.S. the manual makes perfect sense once you understand how the unit works.
After your third or fourth time trying to work out the diagrams you may feel like you understand. Congratulations you do

[ringo]

Originally Posted by Rucksta

Let us know how you go - soon you will be expert.

P.S. the manual makes perfect sense once you understand how the unit works.
After your third or fourth time trying to work out the diagrams you may feel like you understand. Congratulations you do

Hey Rucksta,

Just did a few tries, so currently my nmea network only has about 37+ ohms ( from the b&g website it states i should have 60ohms with 2 terminators connected at the end of the nmea network) could it be that my network has more than 2 terminators or could there be any resistive short in any device caused by water ?
But there doesn't seem to be any more terminators other than the one on the wind sensor and a terminator cap at the start of the network.

[HapaPops]

Is this error the same on the H5000 autopilot computer?

Zeus3, H5000 package and H5000 autopilot computer.

High power connection on autopilot computer is separately switched.

All hanging off a N2K backbone.

With autopilot connected to N2K backbone:

If I don't power up the autopilot high-amp circuit before the computer, I get no N2K data on any display, Zeus included.

If I power up the autopilot first, then the main computer, my displays get N2K data, as does the Zeus but I still get the "autopilot not detected" message on the instruments and the Zeus.

The autopilot has the high amp circuit, the rudder sensor and the N2K wires. Autopilot ram power out and clutch. Polarity on the high amp circuit is ok. Rudder sensor instructions say polarity doesn't matter. N2K connections order triple checked. connections also checked. I think it's connected ok as it doesn't seem to kill the N2K network when powered up before the computer is powered up.

Any idea why Zeus doesn't see it?

[s/v Jedi]

You guys have everything wired seriously wrong. The power connection to the NAC-3 should have nothing to do with the power connection to nmea2000.

Also, it sounds like serious nmea2000 wiring mistakes were made. The measurement for resistance on the data conductors should be done with all devices disconnected from the network. First test without terminators installed, then one, then the other and then both.

Also, I have seen these error messages caused by network errors. You can view network statistics on the plotters and even Triton displays. Also you can see all devices on the network.

If it doesn’t work, start disconnecting things, making the network smaller until just the NAC-3, rudder angle, heading and plotter is installed. If it starts working it was the last device disconnected or the cabling in that area.

[HapaPops]

Mine is actually the H5000, not the NAC, but the network has been working fine. Network power is supplied at one end of the network.... Maybe an issue? But the backbone is only about 20' long

Added the Zeus3 and the H5000 Autopilot computer

Zeus3 works fine

Adding the H5000 autopilot computer - with separate ram power supply as needed. Fuse isn't blown. If ram power isn't on, the entire network is dead.

It the ram power is on, network works, but the Zues and the control head send the message "autopilot not connected"

[s/v Jedi]

Originally Posted by HapaPops

Mine is actually the H5000, not the NAC, but the network has been working fine. Network power is supplied at one end of the network.... Maybe an issue? But the backbone is only about 20' long

Added the Zeus3 and the H5000 Autopilot computer

Zeus3 works fine

Adding the H5000 autopilot computer - with separate ram power supply as needed. Fuse isn't blown. If ram power isn't on, the entire network is dead.

It the ram power is on, network works, but the Zues and the control head send the message "autopilot not connected"

You really ought to hire a professional but anyway, with the H5000 powered off, disconnect it’s nmea2000 drop cable. If your nmea2000 still doesn’t power up, you simply don’t have it powered. If it does power up then the H5000 isn’t properly connected to either nmea2000 or power.

[HapaPops]

Originally Posted by s/v Jedi

You really ought to hire a professional but anyway, with the H5000 powered off, disconnect it’s nmea2000 drop cable. If your nmea2000 still doesn’t power up, you simply don’t have it powered. If it does power up then the H5000 isn’t properly connected to either nmea2000 or power.

Yep, pulled the N2K cable (powered off) - and the network works fine.

Fiddly little connectors for N2K in the box(why oh why didn't they include a N2K standard socket?), I can pull and reconnect.

I think the high-amp power is fine as the green LED lights up.

[s/v Jedi]

Originally Posted by HapaPops

Yep, pulled the N2K cable (powered off) - and the network works fine.

Fiddly little connectors for N2K in the box(why oh why didn't they include a N2K standard socket?), I can pull and reconnect.

I think the high-amp power is fine as the green LED lights up.

My AP computer has screw terminals for the nmea2000. If yours has too, then it is most likely that you shorted out something because of some strands not in the terminal correctly. This can be prevented by using crimped ferrules.
https://www.amazon.com/gp/product/B073TZ5BBG