Gimbal won't power up unless power AND usb connected?
  • This is a new one for me... gimbal seemed to be working fine but I went a month or so without flying. Took my Phantom on a trip and when I tried to power up, the gimbal hangs there dead. No lights, no movement. Plug in USB to computer and it starts up within seconds as normal. If battery power is connected at the same time, the motors are functional and it appears to work perfectly (with no battery power, I can communicate with the board but motors are inactive); as soon as I remove USB connection, it falls dead again with no LEDs illuminated. My suspicion is that there's a voltage regulator somewhere that controls the power fed from battery input to the control electronics, and that got fried; it will work OK as long as the control electronics are getting independent power from the USB.

    Anyone have any thoughts on this or should I just toss the board and replace it?
  • Following up on my initial suspicions, I identified the 1117 voltage regulator on the board and checked the pin voltages...

    With the battery connected (and no USB) the Vin shows as ~12V (battery voltage) and Vout is ~200mV

    With USB connected, Vout jumps right up to ~4.7 volts. So either the regulator is shot or the resistors that adjust the regulator's output got fried somehow. Maybe just a bad trace on the board somewhere. But I somehow doubt I'm going to get it fixed (at least not reliably) without replacing the whole board.
  • I proud of customers who can maintain a multimeter )))

    By the topic, seems that your guess is right about broken voltage regulator.
    That is a pulse reg. AP5100.
    Try to find somebody who can help you with replacing of a broken component.
    It's much cheaper than a whole controller.
  • Thanks! I ended up purchasing a fresh control board just to speed the process, but I'm going to try to replace the regulator when I have time. Good practice working with relatively simple surface mount layout, right?
  • did you ever find a solution to this? I found a quick fix of attaching a battery for phone charging to power the usb mini at the same time. but would really like to fix this (cheaply) if possible!