Arduino Fried Hello everyone new to 3d printing. I purchased a steel Prusa i3 kit and seem to be having trouble with the very last step when i plug it into the wall. Every time i plug in the power supply my arduino board fries in the same spot, I'm a fairly technical person so the fact i can't get this to work is really driving me nuts. I've tried checked my wiring, rewired the board, tried another RAMPS, checked the PSU output with a volt meter( both power lines are putting out 12 volts), and when i ran out of ideas I came here. Anybody got any ideas on how to fix this? https://reprap.org/forum/read.php?4,657223,657223#msg-657223 Mon, 13 Jul 2026 14:25:56 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?4,657223,662969#msg-662969 Re: Arduino Fried https://reprap.org/forum/read.php?4,657223,662969#msg-662969 A good advice, ask someone who knows a bit about electricity to have a look.

BTW, I bought exactly the same power supply (although we never know as they keep copying each others), had a look inside and it seems proper built.

People have just to be careful how they connect the AC, must be properly grounded and protected by a Ground Fault Interrupter plus use a proper enclosure or at least heavy insulation tape.

We don't want fatalities in the community don't we ? Too late for this Italian guy, Arduino isn't ? :)]]> Anonymous User Reprappers Thu, 12 May 2016 04:18:06 -0400 https://reprap.org/forum/read.php?4,657223,662276#msg-662276 Re: Arduino Fried https://reprap.org/forum/read.php?4,657223,662276#msg-662276
[reprap.me]

or newegg in America (there must be lots of others, but I couldn't find them quickly!)

[www.newegg.com]]]> JamesK Reprappers Tue, 10 May 2016 08:37:36 -0400 https://reprap.org/forum/read.php?4,657223,662029#msg-662029 Re: Arduino Fried https://reprap.org/forum/read.php?4,657223,662029#msg-662029
Thanks for all the help JamesK it's greatly appreciated.]]> KyoumaHarshaw Reprappers Mon, 09 May 2016 16:19:31 -0400 https://reprap.org/forum/read.php?4,657223,661686#msg-661686 Re: Arduino Fried https://reprap.org/forum/read.php?4,657223,661686#msg-661686
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KyoumaHarshaw
All 3 show 11.86 volts between the negative terminal and the shield on the USB shield.

Ah, that's wrong and the cause of the problem for sure. I don't know enough about power supply design to suggest how to trouble shoot that, so the best I can suggest is that you get a new power supply. I'd recommend you put a label on this one to record the fact that the negative terminals are 12V above ground. It would be fine for a lot of projects, but not anything where you have to be able to connect things with independent power supplies.]]> JamesK Reprappers Sun, 08 May 2016 16:16:29 -0400 https://reprap.org/forum/read.php?4,657223,661672#msg-661672 Re: Arduino Fried https://reprap.org/forum/read.php?4,657223,661672#msg-661672
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JamesK
Can you measure the voltage between the 0/negative output of your printer PSU and the shield of a working USB cable plugged into the computer (but don't connect it to the printer).
.

All 3 show 11.86 volts between the negative terminal and the shield on the USB shield.

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JamesK
You could also check for AC voltage between the case of the printer PSU and a known good ground (do this very carefully and if you find voltage here unplug the psu immediately)
.

When i checked it was reading in mVolts so i don't think it is anything to be concerned about.]]> KyoumaHarshaw Reprappers Sun, 08 May 2016 15:26:37 -0400 https://reprap.org/forum/read.php?4,657223,660479#msg-660479 Re: Arduino Fried https://reprap.org/forum/read.php?4,657223,660479#msg-660479
By the way, when you measure the voltage, check for both DC and AC voltage difference, and do the AC check first as that's the case that's more dangerous and you want to know about as soon as possible. You could also check for AC voltage between the case of the printer PSU and a known good ground (do this very carefully and if you find voltage here unplug the psu immediately). The possibility I'm considering here is that the ground might have been swapped with either live or neutral which is a potentially life threatening situation.

I'm assuming that your computer is a conventional brand purchased through normal retail channels and so less likely to have a fault than the printer.]]> JamesK Reprappers Thu, 05 May 2016 07:00:20 -0400 https://reprap.org/forum/read.php?4,657223,660361#msg-660361 Re: Arduino Fried https://reprap.org/forum/read.php?4,657223,660361#msg-660361
1. Plug USB into arduino
2. Load firmware into arduino
3. Open Pronterface
4. Connect to Arduino
5. Plug in PSU into the powerstrip
6. Pronterface says connection is lost
7. USB starts smoking and burning

This is the order in the instructions provided with the kit.]]> KyoumaHarshaw Reprappers Wed, 04 May 2016 22:34:15 -0400 https://reprap.org/forum/read.php?4,657223,660358#msg-660358 Re: Arduino Fried https://reprap.org/forum/read.php?4,657223,660358#msg-660358
Did this happen as soon as you plugged the USB cable between the computer and printer, or was it ok until you turned the heat bed on?

Just to be clear, don't connect a USB cable between the printer and computer again until we've worked out what's going on, and be very careful around your printer in case any part of it is carrying mains voltage.]]> JamesK Reprappers Wed, 04 May 2016 21:06:48 -0400 https://reprap.org/forum/read.php?4,657223,660348#msg-660348 Re: Arduino Fried https://reprap.org/forum/read.php?4,657223,660348#msg-660348 KyoumaHarshaw Reprappers Wed, 04 May 2016 19:39:35 -0400 https://reprap.org/forum/read.php?4,657223,659371#msg-659371 Re: Arduino Fried https://reprap.org/forum/read.php?4,657223,659371#msg-659371
Even if my Ramps and drivers and LCD are still good, backups never hurt.

Gonna ditch my OEM PSU and get an atx this evening at frys.

If what you are saying about the OEMs sometimes being miswired inside, I don't want to risk blowing up another arduino or worse arduino and ramps.]]> inverted42 Reprappers Mon, 02 May 2016 12:15:08 -0400 https://reprap.org/forum/read.php?4,657223,659332#msg-659332 Re: Arduino Fried https://reprap.org/forum/read.php?4,657223,659332#msg-659332
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bobc
I would really like to get one of the faulty units and put it into the hands of an EE and get them to examine it.

Yes, me too. This happens often enough that it would be good to fully understand it, and have a simple (and safe!) procedure documented for people to trouble-shoot with. My original thought wast that people were getting the live and neutral mixed up when connecting the power cable, but I can't see a mechanism for that to cause trouble in the transformer based SMPS's that seem to be the most common.]]> JamesK Reprappers Mon, 02 May 2016 09:59:22 -0400 https://reprap.org/forum/read.php?4,657223,659331#msg-659331 Re: Arduino Fried https://reprap.org/forum/read.php?4,657223,659331#msg-659331 www.embedded.com]-

But... I've seen one case here where a cheap DC PSU had it's 12V output connected to earth. On it's own that doesn't matter, if you are driving a string of LEDs. But obviously if you connect that unit to another with 0V referenced to ground, sparks fly.

That would explain a number of cases where Arduino's get fried via USB. It usually seems to be the cheap OEM PSUs, but we also had a problem at work with blowing USB devices on a particular PC. It turned out the mains extension used for the USB device had earth and neutral swapped (despite having an approval sticker on!).

I would really like to get one of the faulty units and put it into the hands of an EE and get them to examine it.]]> bobc Reprappers Mon, 02 May 2016 09:54:27 -0400 https://reprap.org/forum/read.php?4,657223,659320#msg-659320 Re: Arduino Fried https://reprap.org/forum/read.php?4,657223,659320#msg-659320
I was about to try and write an answer to this post when I realised I didn't actually know anything :) Googling SMPS schematics left me more confused as the majority just show the 0V output connected to the ground symbol, without specifying where the 'ground' was obtained. Notably I didn't find any schematics that showed the mains earth connection connected to a ground symbol.

[edit]
Ah, I think I see it - the output 'ground' symbols are defined from the centre taps of the main transformer ouput windings. So the DC output really is floating in most (all?) of these designs.]]> JamesK Reprappers Mon, 02 May 2016 09:06:12 -0400 https://reprap.org/forum/read.php?4,657223,659192#msg-659192 Re: Arduino Fried https://reprap.org/forum/read.php?4,657223,659192#msg-659192 I just made this account to ask this same question.

Not sure what to do. Burned out in the same area.]]> inverted42 Reprappers Mon, 02 May 2016 00:54:29 -0400 https://reprap.org/forum/read.php?4,657223,657697#msg-657697 Re: Arduino Fried https://reprap.org/forum/read.php?4,657223,657697#msg-657697
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dc42
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KyoumaHarshaw
So I should check my connections to the cord that comes out of the power supply to the cord that plugs into the wall?

No, check the wire from the negative output terminal of the PSU to the electronics.

I just re seated the wires and checked all 4 combinations of wires, Red wires are positive and black wires are negative.

R1->B1 =11.86
R1->B2 =11.88
R2->B1 =11.86
R2->B2 =11.86]]> KyoumaHarshaw Reprappers Wed, 27 Apr 2016 19:38:50 -0400 https://reprap.org/forum/read.php?4,657223,657632#msg-657632 Re: Arduino Fried https://reprap.org/forum/read.php?4,657223,657632#msg-657632
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KyoumaHarshaw
So I should check my connections to the cord that comes out of the power supply to the cord that plugs into the wall?

No, check the wire from the negative output terminal of the PSU to the electronics.]]> dc42 Reprappers Wed, 27 Apr 2016 17:05:00 -0400 https://reprap.org/forum/read.php?4,657223,657551#msg-657551 Re: Arduino Fried https://reprap.org/forum/read.php?4,657223,657551#msg-657551 bobc Reprappers Wed, 27 Apr 2016 13:55:55 -0400 https://reprap.org/forum/read.php?4,657223,657534#msg-657534 Re: Arduino Fried https://reprap.org/forum/read.php?4,657223,657534#msg-657534 KyoumaHarshaw Reprappers Wed, 27 Apr 2016 13:20:49 -0400 https://reprap.org/forum/read.php?4,657223,657523#msg-657523 Re: Arduino Fried https://reprap.org/forum/read.php?4,657223,657523#msg-657523 dc42 Reprappers Wed, 27 Apr 2016 13:00:05 -0400 https://reprap.org/forum/read.php?4,657223,657510#msg-657510 Re: Arduino Fried https://reprap.org/forum/read.php?4,657223,657510#msg-657510
My computer and printer are plugged into the same power strip. Do you think I should try and plug into a different wall outlet in a separate part of my house?

I plan on buying two boards from micro center on my way home today to try and sort this out.]]> KyoumaHarshaw Reprappers Wed, 27 Apr 2016 12:32:32 -0400 https://reprap.org/forum/read.php?4,657223,657241#msg-657241 Re: Arduino Fried https://reprap.org/forum/read.php?4,657223,657241#msg-657241
Are you using some cheap usb hub?

Check both ends of the usb are 5v (ie 5v in general on the ramps) and 5v out on the usb from the pc or hub


Also could be a ground loop issue, is everything connected to the one power plug, or is half of it powered from one side of the room and half the other side.. (the latter is bad)]]> Dust Reprappers Wed, 27 Apr 2016 00:14:26 -0400 https://reprap.org/forum/read.php?4,657223,657223#msg-657223 Arduino Fried https://reprap.org/forum/read.php?4,657223,657223#msg-657223
I've tried checked my wiring, rewired the board, tried another RAMPS, checked the PSU output with a volt meter( both power lines are putting out 12 volts), and when i ran out of ideas I came here.

Anybody got any ideas on how to fix this?]]> KyoumaHarshaw Reprappers Tue, 26 Apr 2016 22:28:17 -0400