does burned arduino mean I burned peripherials too?

Hello,

I built a project a while ago with Arduino Mega 2560, LCD module, VNH5019 motor driver, HX711 load cell amplifier, rotary encoder, and switches. Today i burned Arduino by a stupid mistake involving power supply. It should be 12V on Arduino jack port and 24V on motor controller, but guess what, it went 24V in both places. Oh, the smell. Atmega became a frying pan.

Every peripherial is supplied in power through 5V pin, none through VIN. They were not hot after the incident. Can we suppose with good level of certainty that overvoltage was contained in Arduino voltage converter and Atmega? Look, I have two spare Arduinos, no problem. But testing each peripherial would take me eternity (they're partially integrated in a shield and I'd have to solder A LOT, also taking them out of the device, write programs). I could just connect new Arduino and see what happens, but I'm worried that it will die because of short circuit in one peripherial and I won't even know which one of them was it.

I'd be greatful for advice.

There is a clear point of confusion in your description. What are you using to provide 5 V to power all these things? You mention 12 and 24 V, but not what you are using as a 5 V supply. :astonished:

If you burned out the regulator on the Mega by applying 24 V to it, it is not possible to predict whether it passed that voltage on to the 5 V line and damaged other parts or not. When you do figure it out, you need to use a proper switchmode "buck" converter capable of powering all the peripherals, which you can then use to provide 5 V to the Mega as well. The on-board regulator is unable to power other attachments and is essentially useless. :roll_eyes:

Thank you for answer.

Peripherials are powered through Arduino on-board 5V regulator. Don't worry, it has enough power, i carefully measured and calculated it. And it's been running for months before the accident.

Well, i could disconnect the destroyed Mega, supply it with 24V again for a few sec and measure voltage on 5V pin... What do you think?

That will probably only destroy it more.
Toss it, get a new board. Most likely other things are damaged, and even if seemingly working I wouldn't trust it any more.

The regulator is rated probably to 15-18V absolute maximum, so just connecting 24V to it will destroy it, but in what manner? If it fails short, the rest of your board is toast. If it fails open, the rest of your board may still be toast due to the overvoltage while it was burning open.

Why were you even powering the board at 12V in the first place? It's best powered by a regulated 5V power supply on the Vcc aka 5V pin, and any peripheral drawing significant power (>20 mA or so) should be connected directly to that power supply, not through one of the Arduino's power pins. Encoders, switches and sensors generally don't need much power and can be connected to the 5V pins safely.

I mean to test if it failed short or open. I'm tossing it either way of course.

Whole project is powered by big 12V power supply, so i didn't want to add another 5V one unnecessarily. However later I had to add 24V one for bigger motor.

I'll try to test failed board and components and I'll write how is it.

jest92:
Peripherials are powered through Arduino on-board 5V regulator. Don't worry, it has enough power, i carefully measured and calculated it.

I should be interested to know how you did the measurements and calculations.

jest92:
And it's been running for months before the accident.

Ah, well that proves it! :roll_eyes:

Why unnecessary? I'd call it required for anything but a quick test! Your Arduino runs on 5V. Yes it has a regulator built in but it's a linear regulator, meaning your current is limited to no more than 50 mA (7V drop * 50 mA = 350 mW to be dissipated in the regulator), and then your regulator will get pretty hot. Barely enough for the Mega itself, without peripherals. Not a good idea for a long term project.

Just get a 12V to 5V buck converter. Small and cheap, and now you can actually add a few LEDs to your project!

Of course it's a bit of a hassle, but multi-voltage projects are common. For me it's pretty much routine to build 3-voltage boards (12V for peripherals; buck converter for the 5V sensors; 3.3V regulator for the ESP8266 and 3.3V regulators - plus level shifters for the dual 3.3V/5V I2C bus). That's life.

I will probably use your advice and add 5V buck converter. Thank you for your answers.

Answering my own question: I did measurments and tests and however burned Arduino now seems to give <5V on 5V pin, it did in fact destroy most of perihperials. So if anyone have similar situation - don't waste more time and replace everything at once (I left only microswitch board).

Thanks everyone, I think this tread can be closed.