Adafruit Product# 3405 ESP32 Feather Board H.V. damage

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KA7U
 
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Adafruit Product# 3405 ESP32 Feather Board H.V. damage

Post by KA7U »

This Huzzah32 esp32 Feather breakout board was damaged by a discharging capacitor, about 28vdc. I'll post pictures to go along with the investigation. In circuit tests show the following:
Voltage Regulator G3P has 5 pins, 2 up and 3 down. Looking from left to right on the bottom, pin 1=4.6v, pin 2=0v, pin 3=4.46v. Looking from top left to right, pin 4=3.3v, and pin 5=0v.

Voltage Regulator KDDT has 5 pins, 2 up and 3 down. Looking from left to right on the bottom, pin 1=4.7v, pin 2=0v, pin 3=4.1v. Looking from top left to right, pin 4= 0v, and pin 5=4.8v. I think this unit is the damaged one.

Transistor 23X 13, has 3 pins, 1 down and 2 up. Looking down, pin 1=0v, looking up left to right, pin 2=4.6v, and pin 3=4.8v.

Resistor? B5+15 runs hot. It measures a 0.2v drop at the peak. The current through it varies up and down. An ohm meter test with the positive lead on the circuit side, reads 200 ohms across the resistor, from the input side to GND pin, it reads 9K ohms.

What do you think is the likely failure and what is the component sold as? I would like to know.
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2019_0108_225920_003.JPG (216.34 KiB) Viewed 1872 times

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KA7U
 
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Re: Adafruit Product# 3405 ESP32 Feather Board H.V. damage

Post by KA7U »

A friend loaned me another Adafruit Huzzah esp32 Feather board. After comparing the usual suspects on the damaged board, I determined that the voltages around the board matched. This indicates the voltage regulators and transistors are functional, or at least appear to be. The obvious symptom is the sketch loaded on the board does not run, and the board is not recognized when connected to the USB port on the programming computer. It would seem the repair is beyond my ability to identify. So, I gave it to my friend as he is curious to work with it some more.

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adafruit_support_mike
 
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Re: Adafruit Product# 3405 ESP32 Feather Board H.V. damage

Post by adafruit_support_mike »

If the voltage regulator is working, the next most likely source of failure would be damage to the microcontroller.

Once a chip has received damage, there's no telling what can fail next. The connections inside the chip aren't obvious, and the only way to identify the damage is to decap the chip and put it under a high-powered microscope.

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