Introduction: Fix a Fried Arduino Mega

Picture of Fix a Fried Arduino Mega

Sometimes you may do something stupid, other times it is totally inexplicable but as a result of whatever events, the green power light on your Arduino stopped coming on. In my case it turned out to be a burned out voltage regulator.

This inscrutable is a explanation on how to replace it and identify the problem. I couldnt find anything online that explained how to fix a dead Arduino so this may help some people.

(keep in mind that your Arduino could have something else fried, so this wont work in every case)

But also this may work on a regular arduino, if in fact you did burn out the voltage regulator, since they both use the same part.

Step 1: Looking for the Problem

Picture of Looking for the Problem

I was working on interfacing an Arduino Mega with an Irobot Create platform, when for some strange reason i got a power surge on the USB port and the Arduino shut off seemingly for good.

When plugged in, the big overcurrent inductor (in the image below) on the board would quickly heat up, the board wasn’t recognized by the pc and no lights came on.

After thinking what could possible be wrong, the voltage regulator came to mind. It takes whatever voltages go into the power supply and brings it down to 5 volts that is needed for the ATmega chip. The regulator on the board is the: MC33269D-5.0

Go here for the datasheet:

it comes in two packages that do the same thing but look a little different, your arduino may have either one.

Step 2: What Happened?

Picture of What Happened?

To check if the regulator was indeed bad, I used a continuity tester between pins 1 and 2. Luckily I had another working arduino around to compare to. On a working board, there is no continuity, on my broken one, pins 1 and 2 were shorted out.

To further investigate what happened, I refered to the Arduino Mega schematic, available here as pdf:

They also have the eagle pcb file so you can actually see the arduino's design and move things around to see how they are connected. Very useful.

The short in the voltage regulator basically took all the voltage from the usb in a loop over the overcurrent protector and heated it up without powering the board.

I thought since the voltage regulator was for using higher voltage sources with the Arduino, if you took it out, it would work with usb again.

That is one solution. You can totally remove the voltage regulator violently with pliers and the board will work again off USB. But not with any other voltage source in the Vin pin or the 9v jack.

Step 3: Replacing the Voltage Regulator

Picture of Replacing the Voltage Regulator

For this to work again I decided to put in a new voltage regulator. Here is the picture with the voltage regulator removed (this actually still works off usb)

To put a new one in i needed something with a positive 5 volt output, so the common 7805 regulator seemed to be a good choice. Datasheet:

I matched up the connections and soldered it in.

Step 4: Its Back!

Picture of Its Back!

The board was resurrected, it is capable of using other power sources like before. Possibly even higher voltages than the original mega was rated for because of the big heat sink.

If you look closely in the photo, you can see the green light is on!


kees.ricken (author)2017-05-16

Awesome, that did the trick for my Arduino too! Thanks for sharing!

DavidH353 (author)2016-02-03

Thanks for the pointers. My Mega 2560 has a different regulator than yours. Easy enough, and cheap enough. I just purchased fifty AMS1117 5.0 regulators for $5.40 shipped.

BristolA (author)2015-12-24

My 2650 is used in a 3D printer. A few days ago it decided to run the set up process before each print and then stop dead as soon as it got to the Gcode for the print itself. After replacing all of the plugs and wiring I discovered that if I printed from a stone cold printer, it would print. If I tried to print from a warm printer, eg print two successive items, then it would hang.

I have just discovered this article and I am now wondering if it is the VR that is causing the problem. It's either that or a cold solder joint somewhere, but I have been over my 2650 and my Ramps boards with a magnifying glass, nothing visible that looks bad.

I am wondering whether I can simply snip off the original VR and solder a new to the old legs that can remain in the board. It would make an awkward job a lot easier. I can get hold of LD1117S50TR's, so if the pinout is correct, would this be the way to go?

timekiller_9 (author)BristolA2016-01-14


If you have a multimeter, check if you're getting 5V on the output pin of the voltage regulator before bothering. It's a difficult job to replace it in any case so doing so unnecessarily will only lead to further frustration.

My popped voltage regulator didn't really look fried, the only suspicious thing was that I couldn't really read the letter/number markings on it, but then I wasn't really sure if I could prior to the frying incident. Visual inspection is not very telling with tiny electronics components, you really need to test it with a multimeter.

The biggest problem I see with getting a new voltage regulator soldered on to the existing pins is simply getting it to sit flat/straight enough to do so on an uneven surface; it's problematic enough to do so once the pads are smoothed out. Similarly, those existing pin fragments are going to slip once you heat them with a new voltage regulator sitting on top, possibly leading to a short. I have to suggest trying, as I say below, to sweep the pin fragments off after snipping the small one and cracking the bigger back plate by repeatedly bending it up and down.

Secondarily, you may not get a really solid solder connection with the old pin fragment there. It could then work for a time, but may come loose if your Arduino is subject to any amount of bumping around. In my case I use it in my car, so a very hostile environment for anything that isn't bolted down really well!

Any Lx1117x50... should be just fine.

Good luck with it.

BristolA (author)timekiller_92016-01-14

Thanks for the response, but I found a video showing how to check the VR, its definitely cooked. I sent pics to Arduino to see if the board was genuine, but its not, just an excellent copy, right down to the gold chip. I bit the bullet and bought a 100% genuine Arduino, flashed the printer config, and plugged it in. It all worked perfectly.

I will see about repairing the Chinese one, as a spare is always handy to have.

timekiller_9 (author)BristolA2016-01-14

I figured you'd have looked elsewhere by now, but I thought maybe others might benefit from the feedback. Heck, I ended up here just looking for ideas about why my Mega was fried.

You should try to repair the cooked board. It's good practice and worst that can happen is that it's still toast and ends up getting tossed anyway.

Even though it's a knock-off, I'm somewhat surprised that the voltage regulator went out if the input voltage was within reasonable tolerance. You might actually be better off to try to repair the board, use that as your primary again, and see if your device fries the voltage regulator again. If it does, I'd say there's a good chance you're going to fry a genuine Arduino too!

Best of luck with it going forward.

musthy (author)2015-12-14

Just replaced it !

musthy (author)2015-12-14

I asked a few ebay sellers and none of them were sure but this seller was sure and it worked with my fried mega.

timekiller_9 (author)2015-10-07

Thanks to the poster of this instructable for the hints and encouragement.

I repaired my own Arduino Mega today. Symptoms:

1) Sketch would not auto start without reset at USB plug-in/power-up. Otherwise would generally work well when plugged in to USB.

2) No startup at all under any circumstances with power provided to power plug.

3) 3 plus or minus volts measured at voltage regulator output when 9-12 volts provided to power plug from wall wart.

I heard a pop and smelled electrical fire once while attempting to power the Arduino Mega from a car battery (without any other protective circuitry - I was just starting out and knew much less than I do now).

With all due respect to the poster of this instructable, I do encourage others to seek out a proper SOT-223 5V fixed voltage regulator and not use the old style TO-220 package. If you're going to brave soldering in a TO-220, then you're brave enough to try to solder the proper SMD one. For heaven's sake, don't rip the thing off the board with pliers at least, that's a real shame. Today I used a LM1117-5 that I sourced locally (California south bay area) for $0.75 and it works great. Solved all symptoms mentioned above.

Once you've identified the voltage regulator as a problem, start by using side cutters to cut the 3 small legs of the popped voltage regulator. Raise it up with a small jeweler's screwdriver. Then slowly and gently push it up and down with your finger until the large back plate breaks.

Heat up your soldering iron and heat each of the pads until you can push the left over pieces of pin upwards and ultimately take them off the board. If you're lucky they'll stick to the iron and you can use a wet sponge to just wipe them off the iron. The hardest one is the larger back face. You may need to lie your iron a little bit sideways to melt all the solder at once. In any case, your iron will need to be fairly hot for this to work.

Finally, apply the tiniest bit of flux to each of the pads (use chipquik if you can get it, it comes in a handy syringe which is optimal for this purpose). You can position your new voltage regulator on the board and hold it with your finger nail. Take up a little solder onto your iron and tack down the large back pad. Once it's held in place, you can do the same without a finger nail, using just a tiny bit of solder on the 3 small pins. Just be careful of that one resistor or capacitor or whatever it is near by the voltage regulator, you don't want to damage that with your hot iron.

If you're lucky, your Arduino Mega could be brought back from a voltage overload for very little time/money invested!

Good luck all! Again, thanks to the poster for the hint!

FXeio (author)2015-09-26

My Arduino due doesn't execute the program but it is turning on and it begin extremely overheating the processor (I've burned my finger touching it) and some other components. My computer still recognize arduino but if i try to upload the any program arduino IDE says "No devices found on COM6".
Accidently I've connected Vin (12v) pin to another 3.3v pin.

I've attached an image of my arduino, should I only replace only the voltage regulator?

Thanks in advance

TheGreatResistor (author)2015-08-28

fried my raspberry pi 2 any ideas??

Depends on what you fried, if you saw a bright flash, chances are low.

nop no flash and i mostly think it happened since i accidently put 5v thru the 3.3v pin hehehe ....

RedstoneM (author)2015-09-20

I burnt a wire on the board and now i must use an external regulator or do it like you (and add external reverse protection diode and capacitor)

humphrey.lees (author)2015-03-31

I cut off the regulator but the short between pad 1 and 2 is still there. Can I still go ahead with the LM7805? or is something else wrong?

Gelfling6 (author)2015-01-06

I ran into another form of fail on a Mega a week ago.. I somehow corrupted the Bootloader, and had to follow a instructable on here, to reburn the bootloader back into the 2560, using a spare Duemilinova as the ArduinoISP (Files/Examples/ArduinoISP)... It takes roughly 2-3 minutes to reburn the bootloader this way, and despite how everyone else has been using their mega to reburn the ATMEGA328's, even the lowly 168 will program the 2560..

StickyC (author)2014-04-21

For what it's worth, I *believe* the LD1117S50TR is a drop-in replacement. The pinout and current/voltage specs look the same and it's in the same SOT-223 profile as the existing voltage regulator. They're $.50/ea in small lots on E-Bay. It's a tight spot for de-soldering/soldering, so folks who are uncomfortable with soldering might do better with the big chip.

I've smoked mine the same way and will let you know how the replacement turns out.

Fabsterdam (author)StickyC2014-08-20

I just repaired a fried Arduino Mega with just that part (LD1117S50TR) so I can confirm that it is indeed a drop-in replacement. It sure looks a lot better than the 7805 in the original instructable ;).

bblackhat (author)2014-07-15

I repair it with a 7805 but pinout is different..... in 7805 is 1 Vin 2 And 3 Vout

ben0meyer (author)2014-06-12

so, for qualification, the over current protector doesn't need anything done to it

varundev (author)2014-03-27

I have a arduino uno R3. I accidentally shorted the digital I/O pins while testing a rover that I created. Now the uno is not detected in my computer, but the green power led and the pin 13 orange led light up, so I know its not the regulator problem. Is there any hope?

mnhpias (author)2013-11-28

I have arduino mega 2560 R3 . In my case the power led lit up after connecting with source or connecting usb cable with PC but arduino doesn't rspond and PC dont recognize it . what should I do for troubleshooting ? after connecting power , the avr 2560 have been getting hot . pls help me

-max- (author)mnhpias2014-01-27

If you can replace the aVR chip, do that. solder wick might help take solder off the SMD. You can put a new one on with a reflow oven. (These can be made with a spare arduino, thermocouple, and toaster oven.)

-max- (author)2014-01-27

Why did you just rip off the old regulator, it should've have been desoldered so the pads don't lift off. That way the replacement SMD regulator can be put back on for a elegant fix. You can probably find good SMD voltage regulators on old circuit boards, they can be identified because they will often have a few smoothing / filtering electrolytics night next to them. I found one that is rated 5-7A at 5V, quite powerful, although it was a linear regulator, which made me question that current ability when mounted on a standard PCB.

DigitalOSH (author)2011-03-26

Just touched my UNO to the shell of my metal macbook pro... thought it was shot. Thanks for helping me save my brand new purchase (came today!)

Chowmix12 (author)2011-03-10

It doesn't have to be ugly.. I made mine parallel to the board with some creative soldering.

korostelevm (author)Chowmix122011-03-10

Great job! Looks awesome! Did you use the instructions?

Chowmix12 (author)korostelevm2011-03-12

Yep, the i'ble helped with the pinouts... Thanks!

Chancellor1101 (author)2011-01-01

I think id probably run that regulator off board, that looks really ugly. but heck, it works. Good way to save a 50$ board:)

nagkiller (author)2010-12-15


bigbodysmallbrain (author)2010-09-21

you could also buy an smd 7805 and put it on it would look better

I just had the 7805s on hand at the time, if im buying a new regulator i might as well just get the exact one that was on there originally lol

plus its weird now the original regulator had the pins arranged (the ground isnt in the middle) , the surface mount 7805 would have the wrong order and its impossible to twist those things around to match them up like with the big 7805 package

oh i don't have that proplem as i work at a place that repairs laptops and cellular phones so i can "barrow" the parts

kyle brinkerhoff (author)2010-09-23

oh man thats ugly! but hey if it works, thats all its gotta do! next time before you do this (because i know you will cause itell get broken off ) trim the leads down and try to make it work as if it were a smd component it'll last much longer

the_burrito_master (author)2010-09-21

Nice work! I have a dead arduino dueminalove, im pretty sure the problem is the atmel 328p-up I'm planning on getting it fixed by/after Christmas.

TOCO (author)2010-09-21

Cool instrucable. when I saw the picture of it fixed i couldnt help myself. I bust out laughing at frankenregulator. But hey if it works you just saved yourself $60 on a new arduino mega.

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