I've a Raspberry Pi 3 Model B Rev 1.2
Power supply: I'm using a Samsung USB travel adapter charger, output rated at 5V 2A.
USB peripherals: only a RTL SDR DVB-T stick, with R820T2 tuner.
I'm experiencing power LED constantly off despite RPi up and running.
Measuring current draw and voltage, with a cheap USB voltage display, it shows 500 mA and voltage between 4.95 and 4.98V
It seems to me strange the behaviour of power LED: Raspberry Pi 3 Model B has APX803 as voltage supervisor, so it should be off at or under 4.63V.