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I have a problem with my servo motor. I connected a servo to the PWA connection of a PCA9685, but powered the motor externally. There's no problem with that and it works fine with some smaller servo motors. But when I connect the exact same thing to the servo motors I actually want to use, the MC-410, then it doesn't work. Or, should I say, it works very spontaneously. Meaning that the servo moves only sometimes and then for a while not anymore. The problem can't be the servos, I tested them directly with the Pi and they work, just not in my setup.

The whole thing is controlled by a Rasperry Pi 3 B+, the servos are powered with 6V, 1A.

If you have any questions, please ask, I'm happy to explain further

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    \$\begingroup\$ The first step I would take to debug this would be to hang a scope on the PWM signal and check how it looks: amplitude and mark/space ratio. Do you generate the PWM in software from the Pi? \$\endgroup\$ – Oldfart Oct 13 at 12:35
  • \$\begingroup\$ I do not won a scope, so that i cannot do. And yes, I generate the signals from the Pi. The problem that bugs me more is why the smaller servo moves but the bigger doesn't \$\endgroup\$ – YaKe69 Oct 13 at 12:50
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    \$\begingroup\$ Generating PWM in SW on a Pi is unreliable. It maybe that the bigger one needs a signal with a better quality (closer to it's specification). Have you checked the voltage levels? The Pi only produced 3.3Volts, maybe the big one needs 5V? \$\endgroup\$ – Oldfart Oct 13 at 12:56
  • \$\begingroup\$ You do have a common ground, right? \$\endgroup\$ – Chris Stratton Oct 13 at 13:12
  • \$\begingroup\$ That's why I connected the servos to an external power source, 6V, 1A, and they do have a common ground. I just can't explain myself why the small one moves but the big one doesn't \$\endgroup\$ – YaKe69 Oct 13 at 13:15

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