Did I fry my NodeMCU?

So I have a NodeMCU (ESP8266), and I made the n00b mistake of leaving out some metal. As a result, I accidentally shorted some pins to the side of the USB connector, by the Vin, RST, and GRD pins. Now, I have about 1.9V between Vin and GRD, and 0.9 between 3.3V and GRD. That’s the same voltage I read across the pins on the voltage regulator. I’m not exactly sure how to troubleshoot the specific components, to see if it’s fixable. I’m really hoping it’s something that’s easy to replace, but can anyone guide me in some troubleshooting steps? Or if I’m getting less than 2V on Vin, does that mean something is totally borked and I need to throw it away?

2V in = replace LM1117, before soldering new one, check Vin without regulator and resistance Vout pad on PCB to ground.

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If I plug in the USB without the LM1117, it won’t fry anything?

No. All parts are using 3.3V, without voltage regulator 5V stops on PCB board pad.


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I don’t have a spare regulator handy, can I remove this one, then connect it to the 3.3V and GRD from another board to see if it works?

It is the same type of the board ?

I have Nanos, Unos, more NodeMCUs, Seeeduino Xiaos, and Adafruit QT Pys.

Measure resistance to ground all pins to ground.
It is LM1117 warm ?

No, it was not warm.
Resistances as follows:
Vin: 2M
3.3V: 35.5k
RST: 40.1K
Vout pad: 32.77k

= No short circuit so you can connect 3.3V from another source, to be safe use 100 ohm resistor in series.

OK so I connected the 3.3V and GRD with 100ohm resistor (well, I used to 220ohm in parallel, so 110ohms), but I don’t know what program I had installed last, so I’ll have to try connecting it to another NodeMCU and program it that way then we’ll see, I suppose.

it is 3.3 V ok, measure voltage on 110 ohm resistor or current consumed by this board

0.17mA, not a typo

EDIT: took out the resistors, up to 0.77mA, and one LED flashes for just a brief moment.
EDIT2: The LED flashes when I press the reset button too.
EDIT3: It’s working in softAP mode, seems to be all good, just need a new regulator, thanks for your help!

So board is ok you need a new LM1117
they deliver in a few days, free delivery.

temporary you can try to replace regulator by resistor, you need voltage drop on it 1.7V @ 1ma = 1.7 k resistor

What if I power it via external 3.3V, and also use a USB plug? Should that allow me to program it and use it more or less normally until I get the L1117?

should work

Sure does! I guess I got lucky this time! Just ordered the regulator plus a couple spares, thanks so much for your help!

my pleasure