How did I fry my arduino (and almost fried a macbook)?

Is there anything wrong in connecting the Arduino both on the USB and external power?

I've been doing it for the last couple of days without any issue to power the board and run serial debugging at the same time, usually I connected the DC jack first to a 12V wall wart and once the board was powered up I connected the usb.

Yesterday I did it the other way around, first USB, and when I plugged the 12V jack my macbook shut down hard.

The arduino board now seems dead, no 5V, no 3V3, not sure if the damage went past the power regulation section, will check soon. No magic smoke to be seen though.

The notebook fortunately seems fine, but I'll need a couple of days to check everything.

Any idea what could have possibly gone wrong? My take is that there has been a transient before the Vin went to full 12V where the USB 5V went with inverse polarity through the 1117 regulator and burned it. But I'm not sure what happened next.

I'm getting a new board soon but I'd like to understand what happened and do something to prevent it in the future... a USB hub could help to protect the computer?

Where you have purchased arduino boards??

when you powering on either 12v or USB . power LED is on or not??

When you power on just check USB to RS232 converter IC getting heat up or not??

AMPS-N:
Where you have purchased arduino boards??

when you powering on either 12v or USB . power LED is on or not??

When you power on just check USB to RS232 converter IC getting heat up or not??

  1. Have to admit it’s a chinese UNO R3 clone, didn’t state it at first to avoid the easy blame.
    Seems a pretty standard board, AMS1117 5.0 regulator, A1SHB P-mosfet, fuse label “X505” or “505X”, not sure.

  2. No power LED, Vin doesn’t get past the regulator (AMS117 5.0) which seems gone for good. Should I try replacing it with a 78L05 I have at hand?

  3. I have some fear to connect it to the USB again. Tried with a phone charger but nothing happens.

I cannot tell you if and what was fried, but I can understand your fear to reconnect it. My suggestion:

Before you try it again, buy a cheap USB hub which then will protect your laptop, Macbook or other computer's built-in USB port being damaged by an external device, like the Arduino, when that fails.

I only connect my Arduino's via a cheap "USB charger doctor", like this device.

The advantages you get: - protect your Laptop's USB port - monitor current and voltage being delivered to your Arduino

phee: 3. I have some fear to connect it to the USB again. Tried with a phone charger but nothing happens.

Tried with a old laptop. Got plenty of overcurrent messages from the kernel! the fuse gets pretty hot and so does the p-mosfet. .

One way you can try . Yes you can use 7805 regulator IC and give direct 5v and GNd on board appear near to analog port . check the power still on or not.

Power is on Then IC has problem on board.

I strongly recommend to purchase trusted arduino board to avoid these kind of issue. Chinese product are good. I have read in same forum lot of issue found because of chiense arduino board

phee: Tried with a old laptop. Got plenty of overcurrent messages from the kernel! the fuse gets pretty hot and so does the p-mosfet. .

I recommend in this dont do any foolish things. Please purchase good arduino boards .

rpt007: I cannot tell you if and what was fried, but I can understand your fear to reconnect it. My suggestion:

Before you try it again, buy a cheap USB hub which then will protect your laptop, Macbook or other computer's built-in USB port being damaged by an external device, like the Arduino, when that fails.

I only connect my Arduino's via a cheap "USB charger doctor", like this device.

The advantages you get: - protect your Laptop's USB port - monitor current and voltage being delivered to your Arduino

Interesting device, not sure if it really protects against overvoltages and overcurrents though, will do some research!

AMPS-N: I recommend in this dont do any foolish things. Please purchase good arduino boards .

That's the kind of reasoning I wanted to avoid, sure it's chinese and it's probably low quality. But we're talking about a linear regulator, a fuse, and a transistor, not really easy to screw up. The design closely matches the open source one. Just a couple of discrete components differ here and there.

What I mean is, I'm not that sure I would feel safer for my laptop with a genuine board, not until I understand what really happened. Is anyone else used to connect the usb first and the Vin after? should I avoid just this and feel safe? (not really, let's say I'm on laptop battery, power from the mains goes out, arduino switches to usb power, mains get back... and I'm screwed again)

Not a mac person but there was a post a short while ago about an almost exact same situation. Where both USB and Vin were used and it fried the regulator.

There have been a couple more where the 12 Volt was mentioned as being slightly too much juice as the regulators would need to dissipate the heat generated by the excess voltage. I suspect that may be more the case with clones where component quality is not always known.

I would also recommend a "powered" USB 2.0 hub as a primary source of power for exactly the same reasons mentioned already.

That would take "I'm screwed again" out of the equation.

phee:
That’s the kind of reasoning I wanted to avoid, sure it’s chinese and it’s probably low quality. But we’re talking about a linear regulator, a fuse, and a transistor, not really easy to screw up. The design closely matches the open source one. Just a couple of discrete components differ here and there.

What I mean is, I’m not that sure I would feel safer for my laptop with a genuine board, not until I understand what really happened. Is anyone else used to connect the usb first and the Vin after? should I avoid just this and feel safe? (not really, let’s say I’m on laptop battery, power from the mains goes out, arduino switches to usb power, mains get back… and I’m screwed again)

I have used Both on mac and windows platform. I have tried with both connected power supply and USB. But i didnt get any problem. I have brought board which geninue.

Second thing , I have tried one time connected both device with to turn on high power device and upload code same time. In this case i recommend use any one source of power. device remain same unless any sensor, motors being controlled. Its unsafe to work with sensor and motor connected,

Ballscrewbob: Not a mac person but there was a post a short while ago about an almost exact same situation. Where both USB and Vin were used and it fried the regulator.

If you would happen to have a link at hand I'd be grateful

There have been a couple more where the 12 Volt was mentioned as being slightly too much juice as the regulators would need to dissipate the heat generated by the excess voltage. I suspect that may be more the case with clones where component quality is not always known.

Yeah 12V being too much is a suspect. But I've seen regulators die for overheating caused by the too high dropout and it never happened this fast, the laptop shut down hard immediately while plugging the dc jack. It wasn't even completely in yet.

I would also recommend a "powered" USB 2.0 hub as a primary source of power for exactly the same reasons mentioned already.

That would take "I'm screwed again" out of the equation.

Will definitely get one, not that sure it would protect anything though... as I said before, you can find industrial grade hubs with overcurrent and overvoltage protections and they definitely cost way more than a normal powered hub.

Most if not all powered hubs drop out the 5 Volt line to the computer and have idiot diodes when the power supply for the hub is engaged. That will in and of itself prevent most failures going back to the computer and its easy enough to check with a DVM if you have one to hand.

I don't have a link to the posts but you should be able to find them easy enough using a couple of words like "power", "supply", "blown" etc.

Ballscrewbob: Most if not all powered hubs drop out the 5 Volt line to the computer and have idiot diodes when the power supply for the hub is engaged. That will in and of itself prevent most failures going back to the computer and its easy enough to check with a DVM if you have one to hand.

Thank you, what about data lines? I guess I'll go for an opto isolator like https://www.adafruit.com/product/2107, looks the best solution to keep the laptop safe to me.

I don't know this device but looks promising to protect your data lines. But, if I interpret the information on adagruit's website correctly, it will limit the current draw to 100mA. Which in most applications might be enough, but keep this in mind - so you will have to use external power if you need more current.

rpt007: I don't know this device but looks promising to protect your data lines. But, if I interpret the information on adagruit's website correctly, it will limit the current draw to 100mA. Which in most applications might be enough, but keep this in mind - so you will have to use external power if you need more current.

Sure, I need the USB just for programming and serial debugging, and those should work fine with the optoisolator.