Dear @ll,
i recently purchased some ESP32 nodemcu's and while testing, feeding by usb socket i have the following readings:
VIN - GND: 4.97V
3v3 - GND: 4.7V - i understand it should read ~3V3.
Any reason reading 4.7?
TIA
What model is your ESP32? link if possible.
This is the schematic of the ESP32-WROON-32.
See that it has a voltage regulator from 5V to 3.3V (AMS1117-3.3).
Make sure you are measuring on the correct pin.
If the 3.3 voltage is actually 4.7V, then your 3.3V regulator has failed, and as the ESP32's operating voltage is 3.3V, it may have also damaged the processor.
it happened to some brand new ones, plugged the first time and checking the pins voltage 
Most likely a measurement error; i.e. measuring between the wrong pair of pins.
i don't think so, as VIN, 3V3 and GND are cleary identified and no way to confuse it....
Well, it's exceedingly rare in my experience to have boards like these come in with such a major design or manufacturing flaw. In fact, I've never seen it happen. More subtle mistakes - sure. But this is the kind of flaw that would make each of these boards produce smoke upon powering them up.
Does the shiny EMI cover get very hot if you plug in these boards? What supply voltage do you measure on the Vcc pins of the WROOM module?
Can you measure the voltage directly at the output (middle pin) of the voltage regulator ?
@zx80, from which one, please?
thx for the answer. no, it does not get hot (it's also strange).
Voltages measured:
VIN - GND (with usb feed): 4.95V
3V3 - GND (with usb feed): 4.60V
but by the others i have, 3V3 to GND shows 3.32V
That sounds odd. Could you post clear photographs of both boards - one that measures the expected 3.3V and one that measures the weird 4.6V? Top side of the PCB should suffice, good resolution so that any markings on parts are easily readable. Thanks!
Check with DMM if all 3 GND pins are real GND.
@rsmls these are two, one good and one bad.
Well, not much difference there.
One thing that could explain your measurements is if the 1117 linear regulator in the middle isn't soldered on properly. It's hard to see fine detail in the images, but I get a feeling the soldering on the left board may not be quite as good as on the right board.
If I had that board in my hand, I would measure directly on the regulator, test continuity between the regulator's pins and the edge connectors and then take it from there.
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