RAMPS stopped working from mains.

Hi,

Yesterday I have turned on my printer fom its AC switch and saw that RAMPS wasn't working. If I plug the USB cable, everything is operational but without it there is no power going to Arduino. I normally didn't need to use the USB to power the unit on (to use with SD card). What could be the reason for this behaviour?

(Note: I'll check to see if I have unplugged a cable, which could be a possible reason. What I want to know is if there are any other reasons related to a hardware failure which could create this symptom).

Thanks...

I have checked the cables and they seem to be fine. However I can't turn the ramps (and Arduino) on if I also don't plug the USB. I have read somewhere that the USB input and the RAMPS' power input were regulated separately, so I assume there is a problem with the fuse maybe?

I'd like to give an update on the subject. I have ordered a new RAMPS and replaced my old one. The problem persisted. So, I replaced the Arduino MEGA. Now, everything is back to normal. Can anybody explain which part on the Arduino was faulty?

There is a small regulator on the Arduino that sounds like it has died, or the track that provides the input voltage to the regulator is broken.

This regulator provides 5V if you give the Arduino 7V or more on either the VIN pin or the barrel jack. If the regulator works, then the track between the regulator input and the VIN pin could be damaged.

The 5V runs the Arduino, parts of the stepper drivers, and other things on RAMPS.