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APM2 - output rail dead!

Posted by Graham Dyer on May 28, 2012 at 1:40am

Had a flight yesterday morning, tried to have another one later, but the board wouldn't power up at all.

Just checked now and the output rail is dead, it'll power up fine with 5V on the input rail. A couple threads mention a diode that may have gone, if this is case I presume its the diode next to J1 labelled B26.

If so what with what do I replace it, I see there's a few different types? (Please note I have the equipment and am fine soldering SMT components.)

What would cause this to happen, nothing has changed after 100+ flights, now suddenly it dies?

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Tags: apm2, dead, diode, output, rail, why
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Replies

  • Moderator
    Graham Dyer October 2, 2012 at 4:19am

    I eventually put a diode in the position shown on the photo.

    3692517582?profile=original

  • Moderator
    Graham Dyer May 31, 2012 at 9:34am

    I managed to get a couple of the diodes (MBR0520LT1G) and replaced it, board started fine. However plugged in a camera tilt servo into CH6 of my Hitec Optima Rx and the APM2 board went dead. (The Hitec Rx’s have a supplementary power supply for telemetry/electronics). I then discovered that something is weird with that particular Rx it also appears dead until a servo is plugged into CH6 then it works but seems to cause some current to flow blowing the diode again. I have replaced that Rx.

    Tried again with the new Rx but the diode has gone again as the board won’t power up from the output rail anymore. I only bought 2 diodes. It will power up from the input rail.

    So I need to power APM2 from the input rail but my ESC's are the only source of 5v+. Can someone tell me if I can bring + & - 5V from the output rail to the input rail?

  • Moderator
    Graham Dyer May 30, 2012 at 1:53am

    What exactly does JP1 do, if the diode is gone do I still need to remove JP1 to power APM2 with the input rail?

  • Moderator
    Graham Dyer May 29, 2012 at 12:54am

    The part number of that diode is MBR0520LT1G. My board is out of the 90 day warranty that is offered by 3DR so either way I can't send it back.

    I haven't removed the diode, just checked it in-circuit (with a DMM) and it seems open circuit both ways. There is 0.998V on the input rail with JP1 on

    Now...help me out here, what would be the best way to do fix? Replace the diode or could I put a jumper across (bringing +5V and -) from the output rail to the input rail?  Do I still need to use JP1?

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