I've been working on a DIY drone for a while now. It has gotten so far that today I was going to calibrate the PID-constants. While working on it I discovered a major problem.
3 of the 4 motors works as desired, but the forth won't. It worked with the same code that it runs now.
The ESCs seems to be working on all of the four motors, there is the twitching when powering up. But then nothing happens on that motor. If the ESC recieves over about 1500 it starts spinning at a lower speed then the others.
The motors are DYS BE1806 2300kV and the ESCs are DYS 20 amp. The drone is powered by a 3s 2200mAh battery.
Im greatful for answeres and am happy to explain in more detail if required.
Check all solder joints & connections. Reflow them to make sure. Have you had it up in the air yet? It may be a dry solder joint. That came loose. Can you calibrate the esc in cleanflight or betaflight.. Do you own a servo tester, spare motor & esc. To deduct which maybe faulty.
The only other thing I can think of is one of the esc's range is out. If you have blheli configuration app(Chrome) set the throttle range the same as in the cleanflight app. Config tab.
That esc might have something different on it saying only start throttle at 1600 instead of 1000. They need writing all the same.
You could also swap the motor's position, which would prove it's the ESC that's at fault (sort of), then also swap the ESC's position and if the problem follows the ESC
then you know it's at fault, if that arm of the quad fails with a different ESC in it's place then look at the feed lines that supply the ESC voltage and current. As mozquito
said, reflow all your solder connections for that arm too.