Making sure it is safe to put in a new ATMEGA in my UNO


This is my first post, so point out any wrongdoings.

I have an Arduino UNO that stopped working (it got thrown in a box and stopped working). I purchased a replacement that turned out to be a counterfeit. How can I tell if my arduino board is ok to place the conterfeit's ATMEGA in? I checked ic pins, all are at 5v, even when regulator is fed a 12v 1A load. The only thing I see that worries me is that the regulator gets pretty warm, even without an ATMEGA in the board.

arduino is open source, you can buy official boards that support the arduino project, or compatible clones made by other vendors. both a 3rd part compatible clone and an official arduino will use the same atmel atmega 328p chip. that chip is from the atmel manufacture and not made by arduino.

Right, but I am curious to know how I can tell if putting a new atmega 328 in my board will fry it.

it shouldnt hurt it. you can check the volts on your fried board by removing its chip, plugging it in, using a multimeter on DC Volts on the 5v, 3.3v and ground pins on the bottom of the arduino uno. if those read near 5v and 3.3v to ground the voltage regulator is good and you can swap in the chip if you wish. can get a blank atmega chip aswell and use a working uno to program the bootloader on the new chip to have 2 uno's.

Thanks Kundarsa, how about the temperature thing, is it normal for the voltage regulator to get warm even if there is no current draw?

There's always current draw - 3.3V regulator, the power led, the usb/serial chip, the autovoltage selection, etc.
Going from 12V to 5V will dissipate some heat


Thanks, But I am still a bit worried, the fake arduino does not get as warm. I know it has a slightly different voltage regulator.

I wish I could tell you how hot it gets, but the best I have is that it feels like a hand warmer.

My 2 cents: Go ahead and measure with a multimeter your voltage at the 5V and 3.3V pins and see if it is correct. If it is, go ahead and plug the ATmega328P chip in as kundarsa suggests.

In the Vin pin you can feed 7 to 12V. The more towards 12V you go, the warmer the regulator should run. If you would call it warm, not hot, it is probably ok. You can also switch your multimeter to amp mode and measure the current draw and see how the 2 boards compare to each other. If you are not familiar with measuring current with a multimeter you could probably google for some guidance and if you have questions post on the General Electronics forum.

If your fake has the same parts mounted in the same places and you can see the traces run the same as the original, it is a clone and the parts should be interchangeable. If the fake has obviously different parts in a different arrangement, it is a derivative and not all parts are interchangeable. If you have a clone, you can unsolder the regulator from the clone and repair your original. It helps to have good soldering skills, but it's not too wicked of a job. You can also order some new parts, perhaps the regulators and comparator. The schematic has the part numbers and the part numbers may be readable on the parts.

I hooked up my clone and ran it with a 12V battery connected to Vin. After about 30 minutes, the regulators are warm to the touch. I would not call them hand warmers, but I can tell they are warmer than room temperature.


Thanks for your two cents (not sarcasm) it is nice to know that it is probably not an issue. I consider it a fake because it says says UNO R3 on it and everything is positioned in the same place, but the exact component model numbers are different. I assume this is fine but you are welcome to correct me if I am wrong.

To everyone:

Thank you for your advice, I worked up the courage to swap the IC between the two Arduino's, and it appears that my old one has both a bad chip, and a bad USB-Serial converter. I'm getting a FTDI Friend withing a week so I might do some final tests with that to confirm my observations.
Consider this problem solved.