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Dynon autopilot disconnect broken caution

bbaggerman

Active Member
I just went to pickup my new (for me) RV-12. After getting straight and level a few minutes I turned on the autopilot (all Dynon stuff). A little later I started getting an audio "Caution". I had the mash the Message button a bunch of times but finally it told me "AP DISCONNECT BROKEN". Later I downloaded the Dynon Alert Data log file and confirmed this.

The autopilot seemed to work OK and the autopilot disconnect button seemed to work OK the few times I tried it. And looking at the schematic it isn't clear how the Dynon could detect a disconnect button failure anyway. It looks like the button is a simple normally closed button.

Any idea what gives rise to an AP DISCONNECT BROKEN caution? Just judging by the schematics it is hard for me figure how a simple broken switch wire could be detected.

Bob
 
My quick guess...

Not knowing the circuit implemented... There could be something like a 10K Ohm resistor in parallel with the switch. If the wire is broken, then the 10K resistor is not detected, and the system assumes a wire fault.

In your case you say that the switch was working. In that case maybe the 10K resistor broke or was disconnected. I would re-check the wiring, and also review the installation schematic/instructions for such a resistor across the switch.
 
Mine came up with the same alert. Still works perfectly. I was told to go on autopilot settings and turn that alert off. Fixed my issue.
 
Bob,

Early on during initial flight testing, I too kept receiving intermittent "AP Disconnect Broken" alarms ... very annoying.

I just turned off the test because I have many ways to turn off the autopilot .... the button on the AP panel, button adjacent to the throttle, button on the control stick and last but not least if all else fails, the Autopilot power rocker switch. During every pre-flight run up, I check to verify the AP disconnect switches work.

Page 10-13 of the SkyView instillation manual covers the AP disengage ... go to:
SETUP MENU > AUTOPILOT SETUP > DISENGAGE BUTTON > ENABLE BROKEN LINE DETECT .... change from “YES” to "NO". Problem solved.

Edit: If one wants to add the resistor mentioned in the other posts, the Dynon SkyView instillation manual suggests using a 4.7 to 5.3K ohm resistor.

Happy flying,
John
 
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I attached a schematic (from Van's) of the autopilot disconnect switch. I edited out extraneous stuff. A 10k ohm resistor across the switch would be a ideal way to check for problems but I don't see it on the schematic. I'll crawl under the panel and double check but I don't expect to find one there. I'll let you know. I'll probably end up disabling the warning as was suggested.
 

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I attached a schematic (from Van's) of the autopilot disconnect switch. I edited out extraneous stuff. A 10k ohm resistor across the switch would be a ideal way to check for problems but I don't see it on the schematic. I'll crawl under the panel and double check but I don't expect to find one there. I'll let you know. I'll probably end up disabling the warning as was suggested.

Looks like they have a NO and a NC contact monitored within the same switch. Start by checking connection of all four wires. If other people are noticing similar issues, then it might be a firmware/software issue. Have you checked with Dynon support?
 
It is an option in the setup menu to enable the check. If there is no resistor in the system then just ensure it’s set to NO

SETUP MENU > AUTOPILOT SETUP > DISENGAGE BUTTON > ENABLE BROKEN LINE DETECT to “YES”.

There should be a 5k ohm resistor connected from the yellow (yellow on servo) disconnect line to earth for it to be set to yes.
 
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I attached a schematic (from Van's) of the autopilot disconnect switch. I edited out extraneous stuff. A 10k ohm resistor across the switch would be a ideal way to check for problems but I don't see it on the schematic. I'll crawl under the panel and double check but I don't expect to find one there. I'll let you know. I'll probably end up disabling the warning as was suggested.

Zoom out a little :) the resistor is in the AV-50000A. This kind of defeats the purpose, as a break in the wire between the AV-50000A and the switch wouldn't be detected.

My plane is doing the same thing. I'll probably go into the menu and disable it, but it seems like it should be working...
 

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Zoom out a little :) the resistor is in the AV-50000A. This kind of defeats the purpose, as a break in the wire between the AV-50000A and the switch wouldn't be detected.

My plane is doing the same thing. I'll probably go into the menu and disable it, but it seems like it should be working...

If you connect the 5K to a NC switch then it should work, since the 5K in series would be sensed all the time except when a disconnect is requested.
 
Zoom out a little :) the resistor is in the AV-50000A. This kind of defeats the purpose, as a break in the wire between the AV-50000A and the switch wouldn't be detected.

My plane is doing the same thing. I'll probably go into the menu and disable it, but it seems like it should be working...

Duh, missed it. Thanks! I suppose if splice ES-00019 is fairly close to the switch then it might do some good detecting a broken wire. But this leaves out an in-line connector and the actual switch. Not perfect but better than nothing I suppose. Seems hardly worth the effort.
 
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