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?

Looks like a usb related issue

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)

The USB connector I'm using is from an arduino uno kit that I purchased when I was in college so I'm assuming it's good as it has never given me any trouble with the uno unit or the megas until the PSU is connected after the firmware is loaded. I do however have another shorter cable that came with the printer that I will give a try. Could it possibly be that my computer is putting out too much power thru the cable?

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.

If the USB cable gets hot or or the USB connector burns out, then you probably have a poor or broken ground connection in the power wiring between the electronics and the negative output terminal of the power supply.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

So I should check my connections to the cord that comes out of the power supply to the cord that plugs into the wall?

Are you using one of those cheap open frame PSUs? If so it is probably wrongly wired. I would try a different PSU.

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Quote
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.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
dc42

Quote
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

This same thing is happening to me. However it only did it AFTER I hooked the laptop up to its charger.
I just made this account to ask this same question.

Not sure what to do. Burned out in the same area.

Hi, question to the knowledgeable - how is the 0V reference established on a SMPS? I would imagine it is directly connected to the mains ground, but obviously that wouldn't apply to units with no ground connection which seem quite common. For isolated PSUs the 0V could effectively be floating with high impedance so that strapping the 0V lines of multiple PSUs together defines a common level without significant current flow? Perhaps all SMPS use a floating 0?

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.

Edited 1 time(s). Last edit at 05/02/2016 09:19AM by JamesK.

I believe it is normal practice to connect PE (protective earth), chassis and 0V. Safety standards demand that exposed metal parts are connected to PE. So usually, 0V is connected to ground. [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.

---

What is Open Source?
What is Open Source Hardware?
Open Source in a nutshell: the Four Freedoms
CC BY-NC is not an Open Source license

Quote
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.

I ordered a osooyo arduino mega clone comes with new ramps and new motor drivers. Will get here today with same day Amazon.

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.

So I tried the shorter USB cord that was provided with my kit. The attached item shows the result. This is very different that what has happened before. The arduino did still burn out but the cord started smoking that this is the result. Does this mean that it's my computer/outlet then?

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).

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.

I won't be able to do the test until tomorrow up here was what I did tonight.

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.

So I should say that I'm by no means an expert in electronics, and I'm sure there are better qualified people on this forum who will hopefully offer their advice. However, my take is that if there is enough current flowing through the USB to melt the cable when the heat bed is not powered on then the most likely cause is a faulty or incorrectly wired power supply. If it only happened when the bed was running then DC42's suggestion of inadequate connection for the 0V line between the ramps and the PSU would make sense. When the problem occurs as soon as you plug in then it sounds like the 0V level of the printer is different to the 0V of the computer.

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.

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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.

Quote
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.

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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.

Is there a specific brand or vendor that I should be looking for? I'm pretty new to all of this so I'd rather buy from somewhere that others have had success with.

Thanks for all the help JamesK it's greatly appreciated.

I'm using a spare ATX power supply I had lying around, so I don't have a particular vendor to recommend. I would normally buy from ebay or Aliexpress, but given the problems you've had with the current supply you might want to play it safe and buy from someone closer to home. Maybe somewhere like RepRapMe in Europe

[reprap.me]

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

[www.newegg.com]

Looks like this poor lad will end up frying himself unless he is in the US (115V) !
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 ?