Hello!
I am not really sure if this is a problem with the Arduino itself or with my project but I think it fits here.
I developed a PID shield for the Mega 2560, tested it over weeks and finally let it run autonomously over the weekend only connected to a 8V powersupply.
It worked quite fine over the weekend, but sth like 1 hour after i plugged in my computer again it started sending weird data (i do have a "switch case" in my LOOP line and it responded as if i sent some command) over serial and then started smoking and died. There is some specific molten dots on the MEGA 2560 CHIP and on the 1602 CHIP, I hope you can see that on the pictures, i tried to use the flash in order so. Does someone has an idea which lines are burned? The chip got quite hot, because it does do a lot of calculations for the PID, but I assume, that if it is a general heating problem, the burning would not be that punctual.
The board itself supplies the shield which contains of few active components that use 3.3 V. Important might be that I use a transistor to switch a 10 uF capacitor in line between RESET and GND to disable the automatic software reset.
I googled for problems like this, but it seems to be a rather rare case.
to summarize:
- MEGA 2560 + Shield supplied by 8 V over the weekend
- Connecting to Computer on Monday worked, 1 hour later Mega 2560 & Mega 1602 are burned like seen on the picture.
- There is no external power supply on the shield that could somehow overcharge the board
- 10 uF capacitor between GND and RESET
Does anyone have any suggestions? Or any idea which lines where burned? I am just not sure if this is a faulty arduino board.(but why did it then work so long so good) Or if I just need some cooling.
Best,
Tim
