Apologies if this issue has already been identified and a solution provided in a previous post...
Bit of background to the issue - Basically I have a 3D printer which is being operated by an Arduino Mega2560 and a Ramps 1.4 board; sometime last week I tried to run some gcode commands via USB and noticed some smoking from the printer port itself. Upon inspection it looked like it has fried the small chip beside the USB port, trying to use the USB after this was a no-go as expected.
Bought a new Elegoo Arduino Mega2560, plugged it in with no external power (only USB) and I can see the COM port appear no problem, can upload to it etc... but as soon as I plug in mains power I get the Windows sound that a device has been unplugged and then installed, but when looking at Device Manager I'm seeing a warning sign next to the COM port for USB serial device and get the device status:
This device cannot start. (Code 10)
{Operation Failed}
The requested operation was unsuccessful.
Also when trying to connect the printer using Cura, Repetier Host etc I get either a connection issue or it thinks it's connected but doesn't send commands.
Have tried updating the drivers, uninstalling and letting Windows rediscover the port and all basic troubleshooting but to no avail. Looks like as soon as mains power comes into the equation it's a no-go.
power supplies are fighting, for some reason. This is entirely a hardware problem, discontinue connecting it up like that unless you want to fry more boards.
With it on external power and no USB, is everything good? 5v on the 5v rail, etc? If not, there's your problem.
Assuming it's okay on external power, I would try this - butcher a USB cable (or use a socket if you have one handy). Put like a 10k or 100k resistor between ground of the USB cable, and ground of the arduino+ramps board (to prevent damage). USB cable plugged into computer. Measure voltage across the resistor (very carefully - ie, assume that there is line voltage across them), check both DC and AC. Is there any? If yes, the supplies are A) both not isolated and B) one of them has a "ground" that is substantially different from the other. If this is the case, not only is it damaging your boards, its potentially a safety hazard....
That said, there are a suspicious number of people who seem to report frying the USB-serial adapter chip in their arduino while using a RAMPS board with external power plugged into USB.
It may be that the circuit on Ramps1.4 has failed. If the current is too large, the Arduino will burn out. It is recommended that you replace a Ramps 1.4 expansion board.
In addition, the attachment is the power-related components of the Arduino, if one of them is burned, you can replace the components(refer to the Arduino Datasheet) to protect your Arduino Mega2560.
