I have built an Elev-8 quadcopter from Parallax and installed an APM 2.6 flight controller, with external GPS/compass and 915 MHZ telemetry. I spliced an APM power module into the power distribution harness and connected the 5 little wire to the PM port on the APM.
I have cut the power/gnd leads of the ESC signal cables leaving only the signal wire going into the APM; ditto for the receiver channels, except the throttle channel, which supplies power to the receiver.
My problem is I cannot get the APM to arm. I get a GPS lock, and via telemetry, all Mission Planner says is the aircraft is disarmed - no clue as to what, if any pre arm checks are failing.
I discovered the Motor Test function under Initial Setup/Optional Hardware, and tried spinning each of the motors - all work fine except #2. I've gone through a long and tedious troubleshooting exercise:
I connected the motor to a spare ESC and plugged BEC into the throttle channel of the receiver - I can command the motor to run via the transmitter.
Next, I plugged the motor into the ESC mounted on the aircraft and plugged it's BEC into the receiver - same results - the motor spins when commanded.
But when I plug the BEC back into the APM, no joy. I've swapped BEC positions (#1, #2) and the problem follows the motor - not matter where it's BEC is connected, I cannot get the motor to spin.
I'm beginning to suspect a problem internal to the APM itself. Does anyone have any suggestions?
Replies
I'v'e made some progress but still having problems getting all four motors to spin. After some lengthy troubleshooting, I could get all for motors to run in Acro mode, but every attempt to lift off was aborted. The copter would yaw counterclockwise and I could not counter the tendency by applying yaw correction. If I attempted to left off, the copter would pitch forward on its nose, scrapping the two front props on the ground.
So, I tried Stabilize mode. I can arm okay but when I power up, one motor won't spin, typically #1. I've checked wiring and everything seems okay. When I calibrate the ESCs I can get all four motors to spin. But after power cycling the aircraft and arm it, #1 motor won't spin at all. I've tried swapping swapping booms and the boom/motor in the #1 position won't run, so I've ruled out wiring from the motor to the ESC. I've tries swapping ESCs and other things - a spare motor... I will get #1 motor going but then #3 won't spin.
If I go through the same process with motor #3, I can eventually get it working but then the gremlin goes back to motor #1. It's making me crazy! But since #1, #3 are the two front motors, that might explain the tendency to pitch over - if they're spinning slower in Acro mode....
I have the aircraft disassembled and the booms and electronics spread on the floor. I might try to reflash the firmware, but at this point I'm shooting in the dark, and frankly I'm not confident that it will do anything...
This is def a mystery..!
It almost sounds like it's corrupt firmware...
I think that you should do as you suggested.. load a completely different firmware (maybe arduplane?)
Then re-flash back to quadcopter.. remember to select the correct orientation 'X'
Good luck!