I've managed to fry two MEGAs (with two different RAMPS boards in two different printers, actually, but the symptoms are identical).
The Arduino (and the LCD) can no longer be powered through the RAMPS. It only comes alive if I plug it into USB. If I use USB, it seems to behave more or less correctly (shows up as a serial port on my computer, I can upload code, I can connect with PrintRun/Pronterface and issue
Before the second one fried in this way, I did notice that the Arduino was getting pretty warm in the area between the USB connector and the coaxial power connector. The voltage regulator and the over-current protection chips live there, and I've read that a fried voltage regulator is usually the culprit, so I'm all set to order some AMS1117 5v SOT-223 chips. Do these symptoms (RAMPS power no longer powers the Arduino but USB still does) consistent with a fried voltage regulator? Or does it sound like it's something else?
The Arduino (and the LCD) can no longer be powered through the RAMPS. It only comes alive if I plug it into USB. If I use USB, it seems to behave more or less correctly (shows up as a serial port on my computer, I can upload code, I can connect with PrintRun/Pronterface and issue
Before the second one fried in this way, I did notice that the Arduino was getting pretty warm in the area between the USB connector and the coaxial power connector. The voltage regulator and the over-current protection chips live there, and I've read that a fried voltage regulator is usually the culprit, so I'm all set to order some AMS1117 5v SOT-223 chips. Do these symptoms (RAMPS power no longer powers the Arduino but USB still does) consistent with a fried voltage regulator? Or does it sound like it's something else?