Simrad AC42 Rudder Response Failure

[arisatx]

FWIW, I see SIMRAD now has an Aug 2015 update to firmware for the AP24 and AP28 Control heads - V 1.3.03.

There is a reference to V 1.3.03 for the AC42 computer, but only V1.3.02 is posted for download.

This version is to fix intermittent "No Autopilot Computer" errors.

[muttskie]

Originally Posted by arisatx

FWIW, I see SIMRAD now has an Aug 2015 update to firmware for the AP24 and AP28 Control heads - V 1.3.03.

There is a reference to V 1.3.03 for the AC42 computer, but only V1.3.02 is posted for download.

This version is to fix intermittent "No Autopilot Computer" errors.

Good to know, Arisatx. Thanks for posting

[poiu]

I had this same fault message with an older B&G Hydra ACP2 pilot system. It also got worse and worse until it died. A symptom of its imminent demise was an inability to steer sharply to manual power mode rudder inputs to starboard. To port worked fine.

The problem was failed capacitors on the main drive board. You could get and carry spares and an appropriate multimeter to test if this is also the problem with yours.

I wonder if your pilot has a B&G genetic heritage or if it is from Simrad? That would indicate if this suggestion is more or less likely to be useful to you. It may apply anyway of course.

[Fluenta]

Originally Posted by poiu

I had this same fault message with an older B&G Hydra ACP2 pilot system. It also got worse and worse until it died. A symptom of its imminent demise was an inability to steer sharply to manual power mode rudder inputs to starboard. To port worked fine.

The problem was failed capacitors on the main drive board. You could get and carry spares and an appropriate multimeter to test if this is also the problem with yours.

I wonder if your pilot has a B&G genetic heritage or if it is from Simrad? That would indicate if this suggestion is more or less likely to be useful to you. It may apply anyway of course.

The B&G AC42N is really a Simrad AC42 with a B&G logo and NMEA2000 connectors vice Simnet connectors.

[arisatx]

If the wheel can still turn when the AP is in auto mode that means the check valve isn't closing. I suspected the solenoid and even ordered a spare which I was going to swap out yesterday. But found the old solenoid was just "loose". There is a 3/4" nut that had backed off. It's meant to be put on with low torque so I locktited it this time. So far so good today.

Also applied v1.3.03 to my AP heads. We will see if that takes care of the "no autopilot computer" error message.

[arisatx]

Originally Posted by muttskie

Good to know, Arisatx. Thanks for posting

V1.3.03 for the AC42 is now available but the release notes say it is only to accommodate a higher serial number range. No other changes.

[arisatx]

Originally Posted by Fluenta

...
4. Interesting. How did they update it ? Can it me done through the MFD ! I just updated the Triton and Triton Pilot Controller through the MFD. Wish we had a local dealer !

I believe it can be done thru a Simrad MFD. But as I don't have one on our network, I had to buy the Simrad USB to Simnet adapter ST10 finally (I believe it is Kvaser Leaf OEM) after finding that many Simrad techs don't have this adapter in their arsenal of tools.

Excuse the tread drift, but noticed you have a Stevens 47 -
she is a sweet boat.

[Fluenta]

Thanks. Yes we have a Stevens 47 and she has served us well sailing from Seattle to Mexico to New Zealand and now up to Fiji (SV-Fluenta.blogspot.ca).

When we get into NZ I will try the other updates.

Cheers,

Max

[Fluenta]

Three years on we are still getting the occasional Rudder Response Failure. We keep thinking we have a "smoking gun" that we fix and then ... the problems comes back ...

The system was installed installed 2013/2014 and composed of the following components:

System:

- B&G AC42N
- HLD2000L
- Zeus 7 Touch (the primary device for controlling the A/P)
- AP24
- Triton and OP10
- RF300 - Wired direct to the AC42N
- RC42N
- Driving a 32,000 lb Stevens 47 monohull.


On the long passage from Mexico to French Polynesia we had repeated RRF's - often when changing modes (i.e. Auto to Nav etc). When we arrived in the Marquesas we called Navico in the US and did some troubleshooting. On our way from Tonga to NZ the HLD2000L drive itself died entirely and was replaced by Navico NZ. Our assumption was that the drive was the culprit especially as the old solenoid had been knocked off during shipping to us in Mexico.


Last season we headed out with our new drive and still had occasional RRF problems. On advice from Navico we improved some of the wiring to reduce voltage drops and checked again all the mechanical connections. On the way from Fiji to NZ the drive stopped working again. This time it was worn brushes which we replaced.


We have just finished a passage from NZ to Fiji and we are still getting occasional RRF issues. Some of the times it is during benign conditions and more likely if changing modes ie Wind to Nav etc. The problem could be "fixed" by waiting some time and resetting. We also turn off the AC42 for a few seconds too but not sure if this is a placebo or not. If we re-engage the A/P and it does not work, you can hear the pump on the drive "whirring" but no sound from the drive itself moving nor any rudder movement. At this point, even though the autopilot is in 'Auto' the helmsman can turn the helm freely as if the autopilot was in 'standby'. After a few seconds you get the RRF alarm. At that point we just wait a few more minutes and try again. Eventually the A/P will actually engage as we are back to normal.

Sometimes this occurs when the A/P is working hard such as in a following sea but several times it has occurred in benign conditions when the helmsman is able to drive with minimal helm inputs and no excessive weather helm.

I cannot recreate the fault at the dock so troubleshooting is difficult. We do not have easy access to the drive at sea so hard to troubleshoot at sea as one of us needs to drive the boat when the A/P fails.


All mechanical connections seem fine. Brushes and hyd fluid in the drive are good. No evident corrosion in any of the fittings.

Voltage drop data summarised below (Test was done at the dock using NFU with an amp draw of approx 6 amps driving the rudder from full deflection one side to the other):


- Battery to AC42N Supply : 0.2 V


- AC42 Supply (at AC42 terminal) to AC42 Drive Output Terminal: 0.15V (i.e. all internal to the AC42 itself)

- AC42 Supply (at AC42 terminal) to AC42 Drive Engage Terminal: 0.58V (i.e. all internal to the AC42 itself)


- AC42 Drive Output Terminal to the drive unit itself: 0.19V (i.e. the voltage drop along the cabling to the drive unit)

- AC42 Drive Engage Terminal to the solenoid itself: 0.22V (i.e. the voltage drop along the cabling to the solenoid or clutch unit)

Wiring is as follows and is either IAW the installation manual or better:


- Power to AC42N: 10 AWG

- AC42 to Drive: 8 AWG

- AC42 to Solenoid (Drive Engage): 14 AWG


Thoughts:

- The rudder reference sensor gives all indications of working fine i.e. during and after the RRF the rudder angle is correctly reflected.
- The drive is new and the problem pre-dates this drive.
- Wiring - Last year we moved the positive lead directly to the DC Positive Buss vice the old cct panel to reduce voltage drop. I have just moved the negative lead directly to the battery to further reduce voltage drop.
- AC42N - Could there be a problem with the AC42 itself ?

- Is the voltage drop from the AC42 Supply terminal to the AC42 Drive Engage terminal of 0.58V excessive or IAW specifications for the device ?

- Could it be overheating of the solenoid ? Would it help if I mounted a computer fan to cool the solenoid ?
- Based on the noise heard, my uneducated guess is that the solenoid on the drive is either not operating correctly or, more likely, not getting the correct signal to engage the drive.

It at least works most of the time but as we normally do long'ish passages and at least 4,000 nm a year with a family onboard it would be sure nice to trust the autopilot.

Any thoughts out there ?

[donradcliffe]

If it is the solenoid, when it fails you will be able to turn the wheel while the pilot is engaged. This is how I diagnosed my intermittent failure on my new HDL2000 drive.

[Fluenta]

Originally Posted by donradcliffe

If it is the solenoid, when it fails you will be able to turn the wheel while the pilot is engaged. This is how I diagnosed my intermittent failure on my new HDL2000 drive.

That is exactly what happens when it fails. The autopilot shows that it is engaged but the helm can still be easily be turned and the drive does not move the rudder.

The challenge is that the problem is very intermittent so hard to troubleshoot.

[tanglewood]

It sure does sound like it's the solenoid/bypass valve. Here are a few thoughts, questions, and suggestions.

- How exactly is the drive wired to the AC42? Both the pump and the engage solenoid?

- Is your boat 12V and is the drive 12V? Or is one or both 24V?

- Is the drive voltage set correctly in the installation menus?

- Can you confirm that the solenoid coil is actually 12V? There are probably markings on it. And is there a current or wattage rating?

- Assuming it's the solenoid, then a first step will be to isolate the problem to the solenoid coil, the wiring, or the AC42.

- One diagnostic step would be to measure the voltage across the solenoid, and note what it is both when operating correctly, and when operating incorrectly. You could start by measure at the AC42 since that's probably the easiest to access. But if it doesn't indicate a problem, then you will need to measure at the solenoid to distinguish between the wiring and the coil.

- When in standby, there should be no voltage between the two Drive Engage terminals. When in Auto or Nav mode, there should be 12V (assuming a 12V system).

- Another test you could do is wire up an alternate 12V wire pair to the solenoid. Then, when the drive is miss-behaving, apply 12V from another source bypassing the AC42. Be sure to observe polarity or you could fry the AC42. If the drive starts working, then you know it is not getting enough power from the AC42 to activate properly.

My first suspicion would be that the drive engage output from the AC42 is of marginal strength and on occasion the solenoid doesn't fully engage or disengages. Changes on your 12V supply voltage could be all that's needed to trigger it, so low battery state and/or an appliance turning on could be all that it takes, and seem totally random which is what you are observing.

Simrad doesn't publish a spec for the drive engage output saying how much of a load it can handle. I'm going a bit from memory here, but as I recall there is always 12V on the + terminal, and the - terminal appears to be open collector transistor that grounds the terminal when the drive is engaged. There is probably current limiting on the 12V supply side, but I don't know. I know one very experienced installer who had tried using the drive engage to fire the power-on relay on a much larger hydraulic pump, and the AC42 couldn't drive it. I wanted to do the same thing on my boat, so used an intermediate relay and it worked fine.

You could also just jump right ahead and install a relay to drive the bypass solenoid and see if the problem goes away.

[arisatx]

Wow - must be frustrating to have this intermittent and lingering issue.

FWIW, I measured 12.4VDC driving my similar HLD at the terminal strip adjacent to the drive unit.

Per my prior post, I had similar problems / symptoms, with the solenoid-check valve not actuating when it should have been.

1) The solenoid (that I wound up not installing) was actually a Parker


but in a Simrad Robertson box, but all these components would have been changed over when you replaced your drive unit.


In my case, the actual check valve had become loose - I just had to re-tighten (and loctite) the nut on the bottom:



2) Is the hydraulic fluid clean and free of debris that might clog the check valve? Your post indicates so.

3) What version of software are you running on the AC42? There was a TSB for certain high stiction rudders.

4) Assuming you have rerun comissioning a few times, but what setting do you have under Rudder Drive for Motor Output and High Voltage?

5) Is 14AWG sufficient for "drive engage"?

[Fluenta]

Originally Posted by tanglewood

It sure does sound like it's the solenoid/bypass valve. Here are a few thoughts, questions, and suggestions.

- How exactly is the drive wired to the AC42? Both the pump and the engage solenoid?

- Is your boat 12V and is the drive 12V? Or is one or both 24V?

- Is the drive voltage set correctly in the installation menus?

- Can you confirm that the solenoid coil is actually 12V? There are probably markings on it. And is there a current or wattage rating?

- Assuming it's the solenoid, then a first step will be to isolate the problem to the solenoid coil, the wiring, or the AC42.

- One diagnostic step would be to measure the voltage across the solenoid, and note what it is both when operating correctly, and when operating incorrectly. You could start by measure at the AC42 since that's probably the easiest to access. But if it doesn't indicate a problem, then you will need to measure at the solenoid to distinguish between the wiring and the coil.

- When in standby, there should be no voltage between the two Drive Engage terminals. When in Auto or Nav mode, there should be 12V (assuming a 12V system).

- Another test you could do is wire up an alternate 12V wire pair to the solenoid. Then, when the drive is miss-behaving, apply 12V from another source bypassing the AC42. Be sure to observe polarity or you could fry the AC42. If the drive starts working, then you know it is not getting enough power from the AC42 to activate properly.

My first suspicion would be that the drive engage output from the AC42 is of marginal strength and on occasion the solenoid doesn't fully engage or disengages. Changes on your 12V supply voltage could be all that's needed to trigger it, so low battery state and/or an appliance turning on could be all that it takes, and seem totally random which is what you are observing.

Simrad doesn't publish a spec for the drive engage output saying how much of a load it can handle. I'm going a bit from memory here, but as I recall there is always 12V on the + terminal, and the - terminal appears to be open collector transistor that grounds the terminal when the drive is engaged. There is probably current limiting on the 12V supply side, but I don't know. I know one very experienced installer who had tried using the drive engage to fire the power-on relay on a much larger hydraulic pump, and the AC42 couldn't drive it. I wanted to do the same thing on my boat, so used an intermediate relay and it worked fine.

You could also just jump right ahead and install a relay to drive the bypass solenoid and see if the problem goes away.

Wow, thank your for the detailed reply. I had a quick look at your blog and look forward to reading it when I have a bit more time and internet. Heading off some smaller islands in Fiji at 0400 tomorrow to help an aid agency there.

- How exactly is the drive wired to the AC42? Both the pump and the engage solenoid? Both the pump and the engage solenoid are direct to the AC42 IAW the manual.

- Is your boat 12V and is the drive 12V? Or is one or both 24V? All 12 V

- Is the drive voltage set correctly in the installation menus? Yes

- Can you confirm that the solenoid coil is actually 12V? There are probably markings on it. And is there a current or wattage rating? No markings visible but suspect it would have consistent problems if 24V solenoid had mistakenly been supplied. The pump clearly says 12V. Also, the problem pre-dates this drive (i.e. I had the problem even before I had this drive)

- One diagnostic step would be to measure the voltage across the solenoid, and note what it is both when operating correctly, and when operating incorrectly. You could start by measure at the AC42 since that's probably the easiest to access. But if it doesn't indicate a problem, then you will need to measure at the solenoid to distinguish between the wiring and the coil. Yes, but I cannot get it to fail at the dock. I am rigging wires so that at the next failure I can check what voltage is at the solenoid (this area is not accessible easily at sea).

- When in standby, there should be no voltage between the two Drive Engage terminals. When in Auto or Nav mode, there should be 12V (assuming a 12V system). Yes, shows correct numbers when the autopilot is working correctly.

- Another test you could do is wire up an alternate 12V wire pair to the solenoid. Then, when the drive is miss-behaving, apply 12V from another source bypassing the AC42. Be sure to observe polarity or you could fry the AC42. If the drive starts working, then you know it is not getting enough power from the AC42 to activate properly. Interesting idea. I will wait on this one as it is one wiring step too many at the moment.

My first suspicion would be that the drive engage output from the AC42 is of marginal strength and on occasion the solenoid doesn't fully engage or disengages. Changes on your 12V supply voltage could be all that's needed to trigger it, so low battery state and/or an appliance turning on could be all that it takes, and seem totally random which is what you are observing. My suspicion as well.

Thanks again for your thoughtful reply.

Max

[Fluenta]

Originally Posted by arisatx

Wow - must be frustrating to have this intermittent and lingering issue.

FWIW, I measured 12.4VDC driving my similar HLD at the terminal strip adjacent to the drive unit.

Per my prior post, I had similar problems / symptoms, with the solenoid-check valve not actuating when it should have been.

1) The solenoid (that I wound up not installing) was actually a Parker


but in a Simrad Robertson box, but all these components would have been changed over when you replaced your drive unit.


In my case, the actual check valve had become loose - I just had to re-tighten (and loctite) the nut on the bottom:



2) Is the hydraulic fluid clean and free of debris that might clog the check valve? Your post indicates so.

3) What version of software are you running on the AC42? There was a TSB for certain high stiction rudders.

4) Assuming you have rerun comissioning a few times, but what setting do you have under Rudder Drive for Motor Output and High Voltage?

5) Is 14AWG sufficient for "drive engage"?

Thanks for your advice. Frustrating for sure but that seems to be the norm in this industry.

1) In my case, the actual check valve had become loose - I just had to re-tighten (and loctite) the nut on the bottom: Verified that it is tight.



2) Is the hydraulic fluid clean and free of debris that might clog the check valve? Your post indicates so. Yes, looks fine.

3) What version of software are you running on the AC42? There was a TSB for certain high stiction rudders. 1.3.02.00. I tried to find the service bulletin but can only find reference to it on old cruising forum posts.

4) Assuming you have rerun comissioning a few times, but what setting do you have under Rudder Drive for Motor Output and High Voltage? We redid the commissioning when we replaced the drive last year. Drive Engage: "Clutch" Motor Output: "Max". High Voltage: "Off"

5) Is 14AWG sufficient for "drive engage"? IAW the installation manual and sufficient for the max 3A that could travel down it. Measured voltage drop was less than 2% when tested using NFU.