I'm using an Arduino Uno and a PCA9685 board to run 4 servos (of type MG996R). For that, I set up the following connections:

  • SCL -> SCL
  • SDA -> SDA
  • Ground -> GT
  • VCC -> 3.3V

As the servos require high current under draw, I've used an external power supply that is also connected to the PCA9685 at the intended place. The power supply is at 6V (DC) - and max 3 ampere.

Everything just worked fine for about 1 month. Then, suddenly the servos did not move anymore. What I checked:

  • the power supply still gives the desired 5-6V at the PCA9685 board
  • I bought a new PCA9685 board
  • I used another power supply at 5.2V and max 2 ampere (only 1 servo connected)

The strange thing is that even with the new PCA9685 board and power supply, the servos don't move. However, they move if a remove the external power supply and connect the v+ pin of the PCA9685 to the arduino's 5V output pin.

You have any idea whats going on or what might be broken?

  • 1
    sounds like the external power supply is not powering the PCA9685 board
    – jsotola
    Nov 15 '21 at 16:18
  • It would help if you posted links to each of the hardware devices and a schematic, not a frizzy thing. Do this after you verified that the pull ups for the I2C are correct and all the grounds are connected.
    – Gil
    Nov 16 '21 at 1:26

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