When powered there is a slight smell of burning electronics. The polyfuse gets hot.

Part U1 (NCP117ST50T3G or compatible, visibly damaged) has already been removed from the board.

It doesn't enumerate on USB, "ON" LED stays dark.

Power consumption without atmega328P at first at 380mA, then decreasing to 210mA after about 5 seconds. With 328 connected it stays at about 250mA.

I have not yet tested the capacitors.*

Power consumption measured using USB Safety Tester J7-t. 6 other working Elegoo Uno R3 at hand, another broken board (voltage regulator removed also) is still behaving like shorted, and yet another board also behaving shorted (but no visual signs of damage). I don't know what led to this thing breaking down or any history at all - kind of picked it out of a dustbin.

* Is it even worth troubleshooting? Maybe the 3v3 regulator (U2) or T1 are dead, too...

  • you can try poor mans thermal image - spill a little of iso-propyl alcohol on board and watch where it evaporates fastest.
    – KIIV
    Commented May 23 at 16:40


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