I've just finished building my first quadcopter using a kit that's about a year old (APM 1.x). I calibrated all four motors using the manual method (auto-calibration didn't work) and had one successful test run where all four motors responded to throttle appropriately. I then attached the props, went outside, and tried for my first takeoff, but I have not been able to get all four motors to arm/spin up.
* One motor works great, as soon as the APM boots it's ready to go and responds to throttle.
* Motor #2 starts beeping quickly at ~ 2hz but settles down about the time the GPS locks (10-15 seconds) and then responds to throttle appropriately when armed.
* Motor #3 starts beeping at ~2hz (like #2) but after about 2 minutes it too settles down and starts responding to throttle when armed
* Motor #4 beeps slowly (about .5 hz) directly after the initial tones and continues indefinitely. This motor never responds to throttle when armed, so I'm left with three out of four motors working.
In the case of #4 I've confirmed that the motor still responds when connected to a different ESC. I'm afraid the ESC may be dead as I can no longer get it to respond when connected directly to throttle.
I haven't been able to find a guide anywhere describing what the different beep tones mean (other than the calibration instructions). These are 3D Robotics 20Amp ESCs circa July 2011.
Should I give up on the #4 ESC? is there anything I can do about the other two which take so long to initialize?