Dead Pixhawk PX4 after connecting RC

Hey everyone,

It appears I have managed to kill my PX4, and I'm scratching my head as to why...

The relevant parts of my setup include the following:

- Two in-series 3S LiPo batteries connected to a 3DR Power Module

- Power module connected to a PDB

- Two ESCs (which have a 5V BEC built in) connected to the PDB, and in turn, connected to the PX4

This setup worked fine, with my batteries fully charged and connected to my PX4 for weeks of setup and calibration.

Now, I finally come to installing my RC Receiver (TGY IA6C). I plug it into the correct RC IN ports on the rail, connected via PPM to the receiver. The polarity is correct. Now when I go to power my board, everything is fine.

When I power the first motor/ESC, which is in turn supplying 5V to the rail, I hear a popping sound, smell the characteristic smell of burnt electronics, and all lights on my PX4 go dead bar FMC PWR light. The PX4 appears dead, and it appears to have died with the RC pins connected and when applying a second power source to the rail. Note, it was a regulated power source. The ESCs contain a 5V BEC.

I've attached a picture of the output when attempting to run from a connected companion computer. I thought the PX4 supplied power to the RC-IN but not the rest of the rail? Hence the convenience of a built in BEC to the ESCs.

Does anyone have any idea what I did wrong?

Screen Shot 2018-09-19 at 00.44.18.png

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  • Okay you think it’s too much power? 

    I definitely need the two ESC’s connected which each provide 5V BEC power to the rail. I connect the RPi via USB which provides power too, but then have the 3DR connected to the PX4 so I can measure the batteries voltage/current...

    i should mention however the RPi wasn’t connected at the time - so it only had the 3DR power module supplying it. Once the ESC was connected it blew - BUT, it’s had both ESCs, the 3DR module, and the RPi connected before with no problems - it was only once I added the RC that it blew.

    Its seeming more likely that the incorrect wiring killed it?

  • yes I see your issue ! you have too meany power sources to the board! you only need one ! you should not take 5v power from the board but from the BEC only to power companion PC as an example ! 

  • I think you're right @OG! So a photo of the board wont really help because the wiring density and stacking of the electronics is very high: it's hard to see where and how things are connected. I have however created a much clearer wiring schematic which I've attached.

    The cross through the wire connecting the PDB to the right ESC shows it was not connected at the time. The circle with a cross through it connecting the PDB to the left ESC shows the issue occurred when I connected this wire: effectively loading power to the rail with the RC connected. I naturally performed my RC calibration with the motors unplugged, hence this setup.

    I've also attached the a more detailed wiring schematic showing exactly how the signal, ground and power were connected to the rail for each component. I've realised in doing this I *fairly certain* I had the servos and ESCs wired incorrectly. However, they were wired like this for weeks and multiple tests and calibrations with no issues. I didn't explicitly power the motors or servos and have them rotate/move respectively but the PX4 did not explode/blow up. It was only once I powered the rail by connecting the ESC to the PDB with all the signal wires and the RC connected as shown that it blew up.

    Is it possible that the ESCs wired incorrectly could have not killed the board despite loading nearly 24 V into the rail on multiple occasions? And only once the RC was connected that this incorrect wiring killed the board?

    Thank you!


    Main Wiring Schematic.pdf

    Detailed Wiring Schematic.pdf

  • obviously you shored out the board!  you photo is relevant you need photos of your connections on the board! You plugged in something in to the wrong place what px4 board are you using ? 

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