arduino mega heating up and not recognized

Hello everyone,

So i've been trying to build my own 3D printer.

I am using an arduino MEGA2560 and RAMPS1.4 and I was able to move all the axes around fine using Marlin Firmware and Pronterface.
I was able to play around with the axes and heating up the heatbed etc.
When i turned on the printer the next day my arduino mega got very hot and shut itself down.
Now it's not recognized anymore by arduino software and is heating up.

so i unplugged the ramps, and my mega2560 still heats up when connected via USB cable. also it's not recognized anymore. Everything is disconnected from my MEGA2560.
I am measuring around 4.8 volts on the voltage regulator so that rules that problem out.
there is a small block behind it with "U4" written next to it. it is this thing that get's exttremely hot (can't touch it).

I hope there is anyone that can tell me if this is a problem i can fix... and if not does anyone know how this problem might have happened?
too much current? too high voltage?

Hard to say what happened there. But statistically ----- devices - particularly complex devices with lots and lots and lots of components in there can fail at any time, even when new. Just depends on whether the device had a flaw in it, or was previously operated out of regular operation range or limits.

Have you got a spare MEGA 2560 for testing, or for just replacing the busted one?

If the same thing happens, then it will definitely require looking into the circuitry ------ ie. looking into what is connected up to the MEGA 2560, and power supply details etc.

Otherwise, adequate details - actual circuit and wiring diagrams - will be needed (to be shown) in order to maybe spot something that could damage the arduino.

Some common causes for blown chips are over-voltage, excess current (from an output pin), or static discharge (from touching the board when you're not grounded).

An "unexplained failure" in a circuit that was previously working is likely static discharge, especially the board isn't in a box and you've been touching the circuitry.

A failure from excess current (with a logic chip) is not that common... Usually you can short the output without killing it, but it's "not recommended" and not guaranteed.

As Southpark says, you do get "random" failures, but that's rare. The estimated MTBF for the ATmega chip is something like 100 years so the probability of a random failure in the first weeks/months is very low. But it can happen and like he says, the more parts you have the more-likely it is that one will fail.

An overheating part could be the part itself or it could be a different bad/shorted part. For example, if you have a Vcc short or the processor is shorted you'll get excess current through the voltage regulator (if you're powering through the regulator ) and the voltage regulator will overheat. And it's not unusual to get cascading failures where one part burns-up and shorts, and then excess current flows through another part and it burns-up. (I believe the voltage regulator is thermally protected, most voltage regulators are, so if it overheats it's supposed to shut itself down before it dies.) ...A burned-up resistor is almost always caused by something else dying first.

there is a small block behind it with "U4" written next to it. it is this thing that get's exttremely hot (can't touch it).

There are many different Mega clones out there.
Can't find "U4" on any of them. What does the part look like. How many pins does it have.
If YOU provide a picture, or a link, we might be able to tell you why.

Can you please post a circuit diagram of your project, including power supply connections.
How are you powering the hardware and the Mega?

Tom... :slight_smile: