its fairly simple to get autotune to work on a CX-20 or quanum nova
you need a servo extension about 4-5 inches long
now with a pencil knife or simelar sharp object, lift the black tab on the plug and pull all 3 pins out on one end, leave the individual pins on the wire, now remove two from the other plug one from the middle and one from one side, leaving you just 1 wire on the plug
so now you should have a wire with servo plug and 1 wire comming out, and ending in a bare pin
on the flight controller locate the number 4, that is actually channel 8, it can be well hidden its in the lower left corner, there is only one pin, push the bare tab onto the pin
find a way to router you cable to the underside of the quad (out the battery door)
locate S2 it will say Ground(negative) +5 (positive) and S2 (signal pin)
put your newly made in S2 so that the one wire coming out of the plug goes into S2 (not ground, or posetive, the FS allready gets power from the other wires inside the quad)
on my nova the wire has to be toward the middle of the quad
go into mission planner and do a radio calibration, and make sure to turn the nob on your transmitter labeled AUX2....you should be able to see it move on the screen
on config/tune in mission planner set channel 8 to autotune
now go to a nice open space and flip your it into ALT_HOLD and turn aux2 to max and autotune will start, this can take 5-7 minutes, so do it with a fresh battery, if the quad moves too far away for comfort, bring it back, once you let go autotune will resume, when its done, be sure to disarm motors, the new setting does not get written until you disarm it.
once done, simply unplug the wire from the bottom of the quad and and tug it inside the body....this way you can re attach it should the need arise, without having to take the entire quad appart, just make sure it does not get snagged when you put batteries in
sorry the video was so jittery, i will make a better one next time i have the quad apart
