I fried my Leonardo. Is it salvageable?

Shortly after I got my first Arduino, a Leonardo, I plugged it into what I thought was a 12v dc supply. After the board failed to respond for about a minute I realized something was wrong and disconnected it then got out my multimeter. My power supply labeled 12v was putting out over 19v. :slightly_frowning_face:

I've already replaced the board but I was wondering if it's possible to get the first one working again. Is there any chance the main chip is okay and I just need to replace some transistors or something? How would I tell? If the main chip is damaged what's involved in replacing it? Any advice for a noob is appreciated.

Its possible just the 5V regulator is gone. IC1, T1, U3. Do you have 5V on the board?

The 5v pin is giving ~4.8v when I connect USB power and ~5.7v when I plug in 9v from a battery pack. Is that normal?

Why not try powering it from USB and see if it runs the last sketch on it? (I believe by default the blinking LED one?)

If that works, then try programming it from USB.

No 5.7V is too high. Your 5V regulator is damaged somehow.

@ChilliTronix I just realized I didn't make it clear that the board is completely unresponsive at this point. The power and pin13 LEDs come on but otherwise nothing. My computers don't even register a connected device when I plug it in.

Is there a way I can check if the main chip is working? Maybe bypass the regulator if I connect USB power?

Do you know if you loaded a sketch to it before it got fried?

If not it should be running the blinking lights program. If it does nothing, then I suspect the micro controller (Which on the Leonardo is also the USB controller) is fried.

As such the only way to fix it is a chip level repair, which is OK if you like SMD soldering... but beyond economic repair if not.

I never changed the original sketch. This thing was brand new. So I guess this is my motivation to learn surface mount soldering which has been on my to-do list anyway. Any recommendations for where I get a new bare micro controller?

Where do you live? I would find a distributor like Farnell etc., the chips are not cheap in 1 offs. You will then need to load the boot loader.

I live in the US. My new goal is to repair this thing as cheaply as possible and learn more about it and SMD soldering as I do

Well, try places like Sparkfun, DIgikey, Mouser and Farnell. The last 3 will certainly have the Armega32U4. I can't help on how to load a boot loader but there will be information somewhere.

Mouser seems to have the best Atmel prices, plus no sales tax. Shipping $5 to $7 usually.

Do you have an Uno that can run a bootload installer sketch? If not, an Atmel AVR ISP MKii programmer will do all the Arduino chips you may eventually play with. It's all I use for programming. How's the 3.3V look?

Ok so I'll order a new 5v regulator and a new atmega32u4. I'll check the 3.3v when I get home. Is there anything else I should look to replace?

I have another Leonardo but no Uno. Will that still work for burning the bootloader? If not I might have to give up as a programmer is not in my "things I don't really need" budget right now.

The 3.3v pin is working fine. 3.3v from multiple power sources.

Read about Nick Gammon's Arduino as bootloader sketch. I think it could run on Leonardo. http://www.gammon.com.au/forum/?id=11635

Thanks to both of you I think I have all the information I need. Now I just hope I don't suck at surface soldering.

There is only one way to learn! I'm about to buy a practice kit with around 100 SMD devices on it to learn! (Will take a while to solder up)

You need some of this stuff http://www.chipquik.com/store/ It changes the solder chemistry to make it easier to get the chips off.

Hot air rework station with appropriately sized air nozzle for the chip to be removed works well also, 30 seconds of hot air and the chip can be lifted right off.

I have another Leonardo but no Uno. Will that still work for burning the bootloader? If not I might have to give up as a programmer is not in my “things I don’t really need” budget right now.

Read about Nick Gammon’s Arduino as bootloader sketch. I think it could run on Leonardo.
Gammon Forum : Electronics : Microprocessors : Atmega bootloader programmer

I’ve just been updating that bootloader sketch. Previously, although it would run on a Leonardo, it did not have the Leonardo bootloader in its repertoire.

Now it does (latest version on GitHub).

I have confirmed that it correctly programs a Leonardo (bootloader). Pay attention to the wiring diagram on Atmega bootloader programmer. It is different to the one you use to connect a Uno to a Uno, because the SPI connections are not brought out to the header pins (D11 to D13) like they are on a Uno.