I have a DFRduino UNO R3 board. I have a project for sending text messages on it, based on some signals. Everything worked fine yesterday, today I want to continue working on it, I connect 12V to the board and suddenly everything is heating up mercilessly, but for the last days I have always worked with 12V power connected, because I use shield sim7000e in this project. When I connect the board via USB, I can upload the program normally and execute it, of course, communication with sim7000e does not work because 5v from usb is not enough to power this shield. So then I normally connected the power supply to the socket on the board and everything worked and today something happened that the board heats up a lot. The elements circled in red heat the most and only after connecting 12v. Checked this also on oryginal ARduino Uno board which I was using in this project as well and nothing bad is happening with it. Anyone could help me with what is going on? Thanks
Top element is getting insane hot instantly after connection 12v,
12v generates a LOT of heat, more if you have a lot of draw. The power section is toast - the two hot chips on the left.
DO NOT PLUG THE 12V IN AGAIN.
If the card still works on the USB you're lucky. If things are STILL getting hot on the USB, your card is completely fried.
I worked with it for over a week with 12v supply to power up sim shield, and everything worked fine. And on oryginal Arduino same setup works fine too, nothing was heating up. So i wonder what could happen to DFR board or maby what I accidentally did that now this elements heat up like this. And as for this 2 elements on left im not sure if both are heating up. I belive the lower one is heating but as this upper element is lava hot after 1 sec i dont want to plug it again to 12 to check. I think i forgot to mention that nothing is yet connected to inputs of the board
Still its pretty weird for me as I said i was running this board on 12v pretty everyday for over a week, and still have no idea what might cause this heating problem. Also as i needed the sim7000 to be powered up and wanted to program board i had USB and 12v plugged in. Today when i plug USB everything is fine, i can work with it and as i plugged in 12v this sound of unplugged USB was heard.
I used same 12v power supply on my home arduino and never had that problem. During this week time with DFR board i never noticed any heating of any element, I think if it was getting hot to fry it, I would feel this heat on touch?
if you had both usb and +12 plugged in and your computer was off, and you turned the +12 on, the onboard +5 reg (only good for 200mA max) will try to bring up the PC by backfeeding +5 into the PC via the USB. This presents essentially a dead short to the Arduino +5, drawing wayyy more than the max 200mA limit & pfffffft! you have a heater on you card instead of a voltage regulator.
If the reg fails shorted, as they often do, the full +12 gets applied to the cpu and pbbbbt POP! the chips blow faster than you can hit the switch.
To prevent this, I put a switch on the RED wire in the USB cable to interrupt the power and prevent backfeed.
Well it makes sense but im pretty sure i didint plug 12v while computer was off, first thing which i do i always turn on PC and then connect usb and 12v. Could i shorten smth on borad with any cable? I know i had one cable in GND slot when powered up borad. could it somehow shorten smth and because of that elements poofed?
