Hey every one,
I killed my first nano today ... actually two of them and trying to figure out why.
I connected an i2c display but mistakenly reversed its 5v and ground plugs, resulting in a smoking nano, a component actually glowed before dieing on the second one
Congratulations! You have now learned what not to do and what happens when you do it. Welcome to the crowd!
Paul
Illbill726:
....... and trying to figure out why.
You just posted why.. no more guessing. 
I would have thought this mistake would have killed the lcd, not the arduino, lcd still works as well as the rtc module.
Illbill726:
I would have thought this mistake would have killed the lcd, not the arduino, lcd still works as well as the rtc module.
Well, now you know the Arduino gave up first. OTherwise what you wrote would be true.
Paul
Now to narrow down what burnt on the arduino, if you flip the nano over so your looking at the underside of the usb port, there are 3 components attached at the usb port, the black component in the middle is the one that glowed and melted, any one know what this is ?
The Nano will most likely still work with 5volt on the 5volt pin, or 6-9volt on V-in.
The burned part is just a common 500mA schottky diode, used for USB supply backflow protection.
Any smd schottky diode will do.
Leo..
Hmmm. You do things differently than I do.
If I accidentally make something glow red, I ALWAYS have my finger on it at the time!!!!
:o :o :o
Ok I will give it a shot, but question is, if powered through vin, can I still connect to pc with the usb for coding purposes, and will the usb port still work, and do I risk killing my pc plugging this in and powering it from the vin pin with a 9v supply
Depends, if that diode is shorted or not.
If it's open circuit, then you can use the Nano normally.
If it's not, it could damage the PC/laptop.
Wise to remove (desolder) the charred remains of that diode.
Leo..
Ah, now you have a Nono!
(well, it made me smile)
Steve (getting coat)
Welcome to the club ! if you didn't do that you wouldn't learn, now you will know forever what not to do
So it powered with 9v on the vin pin,
So I dug a diode out of a gikfun starter kit, and used it to bridge the surface mount diode and the arduino is alive again, here is a image to show what I have done.
I tryed to remove the surface mount diode but even with a butane soldering iron i didnt have much luck. The heat from the soldering iron practically melted the original diode.
At least it works
https://www.amazon.ca/photos/share/jgtce7MkqYA0OhPn4GblSY1Gsi2wRWG3idlHgtgPrMa
De-soldering is done with more solder. You need the flux of fresh solder to remove old parts.
And never put the solder directly on the tip of the iron. That instantly burns the flux.
You seem to have used a 1N4007. Should have used a 1N5819 schottky diode (or smd schottky).
VCC of the Nano is only about 4.3volt with a common 1N4007.
Works, but you could have issues with 5volt sensors.
Leo..
What issues do you expect with 5v sensors, have not plugged anything but a rgb led into it as of now
Just tryed it with a DHT22 sensor powered with the 5v pin, let it run for a few mins and seems fine
The DHT22 also works at 3.3V just fine, so at your ~4.3V it'll also be perfectly happy. Some 5V sensors require at least 4.5V to work properly.
vinceherman:
If I accidentally make something glow red, I ALWAYS have my finger on it at the time!!!!
Nothing beats having a burn mark in the shape of a TO-220 on the tip of your finger That 7805 didn't burn, just overheating a bit, making it painfully clear it needed a heat sink.