Reverse polarity

I have been flying a 3DR Quadcopter for about 8 months and made a huge mistake by touching my battery leads to the power cable in reverse polarity - I didn't plug it in, the connectors just touched. That was enough to do something to my APM 2.5. When I try to connect to my computer via USB it only sees it as an "unknown device" and installs it as such. The red and blue lights flash and then go to red blinking.

Anyone have any suggestions?



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  • Developer

    Are you good with a soldering iron?  If yes, I'll bet that you need to replace the APM2.x's 32u2 (aka ppm encoder).  That's responsible for the USB connection and reading the input from the receiver and it's perhaps been fried.

    I'd double check the 3.3V line (take it out of it's case and and the bottom you should see a 3V and GND labels) to make sure it's still 3V and not 5V.  If it's 5V you'll need to replace the 3.3V regulator.

  • Sorry for the incident.

    Possibly a sudden surge of current draw may have caused a brown out of APM. Did you use a 'power module'? If you did use it then the power module may have been damaged due to the incident but APM would still be safe.

    Try to give APM some good rest; later try to connect with a USB and test in the simple CLI mode if things work.

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