lost autopilot servos

[dbhill916]

Hello all,

I'm seeking a pointer on where to start looking for my autopilot servos. I know they're installed in the airplane, but my Skyview can't find them anymore. I was successful in having them recognized when I did the avionics installation, but they no longer are visible to the system. Both servos "disappeared" at the same time, leading me to suspect a single point of failure. I've tried to read the wiring diagrams, but I'm not having much luck figuring out where to start. (The PDF versions are much more user friendly?thanks!)

Any suggestions welcome,
-dbh

[BigJohn]

Since both dissappeared at the same time I would think it most likely you have a configuration problem in the SV rather than an electrical fault.

[Mich48041]

Make sure the autopilot switch is turned on and the fuse is not blown. Which electrical drawing do you use, before of after 8-25-2011?

[WingedFrog]

I had this same problem when I first flew the plane. Here is a copy of what's in my logbook:
"The cause of the Auto Pilot malfunction was found: a pin distributing power to both servos was not locked in the optional connector. Just pushing the wire solved the problem, now the servos are found by Skyview. Calibration and test performed successfully!"
The connector in question is on the VAN's interface box in the avionics shelf.

[chrishalfman]

I had the same thing happen to me. Twice.

I agree with the trouble shooting. I had purchased too many (one left over) network cables and used it to test my system. I verified the cable was good checking continuity on each wire and that the ground was grounded and the power had power. Nothing.

I had just updated the Skyview firmware at that time and the circuit boards in both servos lost their minds. (Guessing it was cheap boards that couldn't take a new firmware 'burn.') Actually had it happen twice-each time after a Skyview firmware update. They got it fixed after the second time. No issues in the last 16 months or so.

[dbhill916]

thanks for the pointers, gentlemen.

Sorry, I neglected to mention that I did verify the fuse was intact and AP switch is ON. No new configurations since I last 'saw' the servos, and I'll hold off doing the V14 upgrade until this is resolved.

I am using the SV-AP-KNOB_04-03-14.dwg since I did install the optional AP panels. BTW, those seem to be working (i.e., things change on the SV when I turn the dedicated knobs.)

MMiller: thanks for the quick synopsis of the connections. Very useful for understanding how things work.

WingedFrog: I'm hoping that there's a similarly easy fix. Hopefully the power pin vibrated loose during engine ground testing. I'll let you know what I find. Unfortunately, it'll be a few weeks before I am back in town and will have time to troubleshoot. stay tuned!

thanks again,
-dbh

[Mich48041]

Check the AV-50000A "Options" D-Sub to make sure all of the pins are firmly seated. Check for power on pin 19.
If all is OK there, then check the power-wire butt splice. According to the schematic, that splice is located 27" from the pitch servo, maybe in the center tunnel?