No solder method for defective 3.3V regulator for APM


Discovered a method to provide an alternative 3.3V for powering the onboard Baro, Accelerometer, Compass when the built in 3.3V regulator TPS79133 fails.

I documented the details and equipment required here

No solder method to provide alternative 3.3V source to the onboard sensors.

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  • Great solution. It worked like a charm and got my APM flying again. No more worrying about blowing another regulator. Thanks for sharing this.

  • I use a Arduino Micro, powered in "voltage in" with 5v UBEC and feed the APM directly with 3.3v.

  • Is the actual board a 3DR?

  • The board pic was a screen cap that was grabbed off the net..

  • @Swift -  Fair enough.  Thanks for pointing it out.

  • Nice simple solution!  Great for fast repair should the reg give up in the field, and just as easily reversed when you get back to base.

    I have been extremely impressed with the performance of this particular 3.3V BEC (directly powering the TX in this AV link). NOTE: I am assuming that there is no reason why the 3.3V rail wouldn't be equally happy powered by a switchmode regulated supply as it would a linear one, so if this could be confirmed by a bigger brain that would be tops!

  • Developer

    The only issue I would be concerned about here is where to source that extra 3v3 and when you do, it needs to be a regulator that can handle the extra demands ie. current draw on it. Otherwise it will be a cascading number of 3v3 regulators failing

  • I have replaced the regulator a couple of times on my APM2.5.2 board. It seems to happen after disconnecting the APM whilst still connected and while powered by external battery.

    Since I have been disconnecting from mission planner first, I havent had any issues.

  • If this is a common problem, why can't you return it to 3dr?

  • +1 with John's warning.

    The space is probably too small to use a Dremel cutting wheel.

    More likely you could use a heavier hobby knife blade and shear the device leads off at the case -- it might take several chops to get a lead cut clean.

    Once sheared off, the (presumed) dead chip body can be removed.

    Overall, it is a valid method of salvaging or repairing an APM with a faulty 3.3 V reg.


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