roll servo off line

[johnsteichen]

On a short flight today, I got a roll servo off line warning. It has worked flawless for a number of years and no recent work was done in the area of the servo. I pulled the breaker and it seemed to fix the problem, but after a couple of minutes, it went off line again with the warning. Any suggestions, before I call techinical service?

 

[jakej]

Just out of curiosity, what type of circuit breaker & how old ?  I have seen avionics go 'offline' due to circuit breakers having a high internal resistance causing an offline event but not physically popping.  A simple check would be to use another breaker or temp hardwire ( with inline fuse) the servo to the bus. There may be other reasons why the servo is going offline but the check above is easy to do.

Jake J

 

[Dynon]

SkyView or D10/D100 series? If SkyView, are you seeing any other warnings that are SkyView Network oriented?

 

[johnsteichen]

This is a skyview unit. There is no other network warnings that are being triggered. When I reset the AP circuit breaker it works for a while and then goes off line.

 

[dynonsupport]

We concur with our very smart friend Jake - we've also heard of flaky circuit breakers causing this kind of issue (diagnosed only after several servo swaps); replacing the circuit breaker fixed it.

From the symptoms, assuming the circuit breaker is good, contact Tech Support for a Return Material Authorization - email support AT dynonavionics DOT com.

This is a skyview unit. There is no other network warnings that are being triggered. When I reset the AP circuit breaker it works for a while and then goes off line.

 

[johnsteichen]

OK thanks, I have a new C/B ordered and see first if that is an issue. Will contact service after results of the swap. Thanks.

 

[Tracy]

I am having a similar problem with my pitch servo. When running my initial servo calibrations my pitch servo wasn't found by the skyview. I finally sent it to Dynon and they sent it back and it was working fine. I am now flying the plane and when I started testing the AP in simplified mode I only had Trk not Trk-Alt. When I checked the status of the servos only the roll servo was listed. I did a detect and a force load and nothing worked. I went flying today and when I got back I tried again to get the skyview to detect the pitch servo and it did. I went through the calibration procedure and everything was good but when I started the engine "pitch error" was on the skyview and the warning button said that the pitch servo was offline. Now I can't get the skyview to detect the servo again. Dynon is sending me another servo but I would rather not change it out if I don't have to. Oh, and the first time this happened I tried both harnesses at the roll servo and both detected the servo but neither harness detected the pitch servo. This is why I figured it was the servo and not the harness wiring. Anybody have any ideas??

 

[jakej]

Tracy

Try powering up the autopilot system after engine start (you may already be doing this) & then see if the autopilot stays on line, that may be helpful to know.
I've known of 'faults' with network items having issues due to the voltage 'spike' when starting the engine. Can happen to various avionics.

Jake J

 

[Tracy]

Here is what I found out today while troubleshooting. I have a switch on the panel that turns on the transponder and com radio. If a have this switch off the skyview will detect the pitch servo and I can calibrate it and everything is fine. When I then power the transponder and comm the pitch servo goes offline. If both roll and pitch servos went offline I would think something is wrong in how I have wired something (still could be I guess), both servos are on the same circuit breaker and both harnesses go to the SV-Hub. Hope this gives someone some more info to help me diagnose this cause i'm beginning to think it isn't the servo.

 

[jakej]

1. Do you have separate circuit breakers (or fuses etc) for the power wires for the Com, Transponder & Autopilot servos ?
2. If NO to any of the above, how did you wire them ?
3. Did you connect the Servo harnesses directly between the servos & the hub ? If YES then that is one issue that needs to be rectified.
Servos - the ONLY wires that connect to the network are these 4 - blue/white, green/white, blue & green (pins 4&8, 1&6).
Section 10.1 of the Install Manual covers this.
It would be easier to PM me or contact support directly to 'walk' you through the troubleshooting.

Jake J

 

[Tracy]

Jake, the servos are on the same CB so both have the same power source. The com and transponder are on a different CB but together. Not sure what you mean by connecting the servo harnesses directly to the hub? Both servos have a different harness to the hub wired per the manual. Both are wired the same and I don't have any trouble with the roll servo.
Am I missing what you are asking?

 

[jakej]

probably best/quicker if we talk directly - check your PM

Jake J

 

[Tracy]

Update, for all of you who might have this problem or who are in the process of building a composite fuselage plane. It turns out that my transponder antenna was two close to my pitch servo and RF waves were maki g it go offline. Wrapped the servo wires in aluminum foil and problem solved. Many thanks to Jake for helping me with this cause I don't think I would have figured this out near as quick.

 

[dougnlina]

Thanks for this update. I have been following this thread because I have an intermittent, somewhat infrequent "pitch servo off line" It is mounted within a foot of the transponder antenna, I will try the tin foil

 

[johnsteichen]

OK Here is an update on my roll servo problem.
a bit of history. My dynon transponder probably has been functioning at very low power for many year. Even at very low power, ATC would recognize it and then at some point on a cross country trip, they would complain and I would give them my second transponder ( Garmin) to solve the problem. During this time, the roll servo worked flawlessly. Recently, I finally got around to sending the transponder in for repairs once the avionics shop isolated the problem to the transponder, and not my coax or antenna installation. Funny thing, with the full power transponder, now my roll servo started going off line. The antenna spike with its roughly 6x6 ground plane was within 15-18 inches of the roll servo and its wiring. This discussion thread headed me in this direction. I tried some aluminum foil around the wires and even wore an aluminum foil hat just in case 
That did not work as a fix for me. Soo..
I moved the dynon transponder antenna to a further away location.
In a fiberglass aircraft, it was an easy move.  Quick and dirty to prove out the solution. Drill a hole in the belly in the baggage compartment and poke the antenna/ground plane assembly  out the hole. Duct tape it in place temporarily on the inside and go fly.
Problem has disappeared . I will fly with the temporary install for a while until I feel guilty about the duct tape and the easy routing of the coax, over the top of the seats. 
I love experimental aircraft !!!