sparks when connecting usb cable for firmware upload

[fnorkn 2]

So I have successfully uploaded custom firmware for my UM2 a couple of times before (getting my dual printhead to work), but now something wonderful has happened...

The printer works fine, but when I connect the USB cable from my laptop or computer to the UM2 USB port, the metal shield of the plug gives off sparks ! Fireworks! W00t!

The cable also gets warm pretty soon.

The upload fails, off course.

Any ideas what may be wrong?

Or how to solve it?

[gr5 2,069]

Wow. Grounding issues. Unplug your laptop from your charger and anything else connected to house power (like speaker system amplifier - anything) I bet that fixes it.

Plugging laptop to a keyboard or mouse is okay but unplug it from anything else like printers, ethernet, and so on.

So then figure out which piece of equipment has grounding issues. Probably one of the plugs in your wall power is wired up backwards. You can determine this with a volt meter.

Another alternative - plug the laptop, 3dprinter, and everything else that is powered (including ethernate router!) into the same power strip so that none of them has a ground signal that is at full AC power.

[niyoki 21]

You can also use another usb cable...Or first connect Usb cable to the UM2 then you can power on Laptop then UM2.

[fnorkn 2]

Hmmmm

Thanks for the input!

I had the laptop running on batteries, and it still sparked.

Tried another usb cable as well...still sparks....

My hous has an "aardlek"-fuse so if any current would be leaking from the mains to earth, it would trip.... I will investigate further this evening.

[fnorkn 2]

Does anyone know what has been burned away here?

I think it's a SMD component labeled L1 or something.

I keep getting Temp Sensor errors when starting up with this fried puppy.

:(

Edited February 3, 2016 by Guest

[gr5 2,069]

ULTIMAKER 2 SCHEMATIC and layout map - click "raw":

https://github.com/Ultimaker/Ultimaker2/blob/master/1091_Main_board_v2.1.1_%28x1%29/Main%20Board%20V2.1.1.pdf

 

[fnorkn 2]

Thanks gr5

It is L1 indeed, an inductor (coil) ?

Got a link for a component list? I need to know the inductance and stuff so I can solder on a replacement, see if that clears things up... (don't think so but hey...)

[gr5 2,069]

Yes, L1 is an inductor. It is meant to discharge any static slowly to ground.

If your laptop is truly not connected to anything such as an ethernet cable - then I'm very surprised - something is very strange here. I would measure the voltage of your USB with a voltmeter - measure the voltage between the shield and your house ground. Same with UM2.

[boelle 1]

hmm

first of all we dont know where fnorkn is from, if from Europe somewhere we have live, neutral and earth in the wall. and we also have a combined earth leakage and leakage failsafe in the fuse panel that will cut all power from the street if one of 2 or both conditions are meet

1. current runs from live to earth, ie from live to metal chassis
   
2. more current goes in the house than out, ie it compares the 2 and trips if to much difference, 30ma or less
   

my best bet on this one is voltage differential... ie the GND plane of the PC's usb port and the USB port of the printer are not at same level

also i would hunt and check ANY changes made before/after the problem came up

[boelle 1]

looking at the schematic..

i would start out by meassure the voltage between the shield of the usb comming from the pc and pin number 5(or 4).... should be 0V

also does things spark if you unplug the power supply to the UM2 ?

with the UM2 power supply unpluged what voltage can you meassure on it? pin out here: http://www.aliexpress.com/item-img/AC-DC-adapter-power-supply-for-Ultimaker-2-UM2-Extended-3d-printer-24V-12-3A-10A/32503516739.html?spm=2114.12010108.100005.5.hWtQlT#

Edited February 8, 2016 by Guest

[boelle 1]

thanks for the like, but did you figure it?

[fnorkn 2]

fnorkn lives in the Netherlands.

Still working on it.  I bought a replacement board from China, I plugged all the cables in WITHOUT attaching it to the machine... it booted up just fine. All green across the board.

Then I thought: success! Attach the mainboard and continue tweaking my dual filament head setup.

But the frame of the UM2 is some sort of plastic laminated with aluminum..

So when I turned on the power, I saw some red led lighting up (hard to tell, you're looking at the bottom of the PCB),  and sparks where the USB connector apparently touches the frame.

Now it is giving me the same error as the original PCB (I guess the inductor is not really  a critical part ): heater error. I guess the electronics that measure the heater-sensors are fried....again. Looking at the board, I suspect it is a triple layer : top, middle (hidden) and bottom.

This stuff is above my pay-grade.

Perhaps I will purchase an open-source 3d printer-board and hook it up, see if I can make it work...

Edited February 28, 2016 by Guest

[fnorkn 2]

I recompiled the firmware with a more fun error message , and explaining the root cause for my sad adventures: max temp reached.

Which is bogus: same message with or without sensors attached.

Edited February 28, 2016 by Guest

[gr5 2,069]

max temp is what you get when it measures infinite ohms for the temp sensor. Disconnect that cable on your PCB and measure it yourself directly. It should be around 108 ohms at room temperature. Anything 100-120 ohms implies the temp sensor is fine.

[fnorkn 2]

Yeah, did that already.

All 3 are 110 Ohms... (heater1, 2 and heated bed)

And like I said, when I hooked up my new board, but not screwed onto the ultimaker, it booted fine. The problems (again) came back when I installed it onderneath the UM.

 

I think the comparator-chips that are attached to the heat sensors have been fried.

The specs say that they are sensitive to static charges....

[fnorkn 2]

Update (for anyone having the same problem):

I measured the output voltage for the 3 opamps, attached to the 3 heatsensors (temp1, temp2 and heatbed). One of them did not generate a voltage like the other 2.

I ordered a replacement opamp, and yesterday I had time to solder it on. The SMD chip is hopelessly small, but everything went fine. I also replaced a capacitor, but that was probably not necessary.

Long story short, after replacing the faulty opamp the Ultithing booted up correctly!

I put Kapton tape where the board switch and power connector go through the housing, so no more sparks there.

I will post a picture if I don't forget.

[neotko 1,417]

Great! I use kapton to isolate heat masking the area I won't work when I must change the transistor of the pwm so it's easier to replace a component on this small smd chips.

[fnorkn 2]

So I promised a photo of my handiwork. Probably the absolute horror of SMD experts: sputtered soldering metal and misaligned chip, but it is my first time and I goddamn hated the experience. It is all so tiny, even a magnifying glass is hardly helpfull. Anyway, it did solve my problem, so my conclusion is that the opamp was busted.

[PBJ-Designer 0]

Hi Guys/Gals,

I've finally stumbled upon a thread where people mention shocks or sparks!

I've had serious issues with shocks from my UM2.

When touching the cabinet, screws or any metal part - except from the print head - I can feel the buzzing of current, and when I touch more places than one, i get a snap at my fingers!

I can't figure out where the issue is, I've tried moving it to different outlets and that didn't change a thing. At the moment I'm trying to home in on the issue, one part after another.

Have anyone had a shocking experince like this, and how did you resolve it?

This is a very serious issue, and I've had it for at least 8 out of the 10 months I've had the printer.

NOTE: wearing shoes does make a difference somtimes!

[PBJ-Designer 0]

I've been having issues with my UM2 printer giving electric shocks recently.

It's not a static "I've-rubbed-against-the-carpet-too-long" kind of shock, it's the "This-blue-spark-made-my-finger-go-numb-for-a-day" kind of shock.

I've been trying to figure out what to do and find out what kind of problem could be at hand here, but so far no luck.

Have anyone had an electric issue with your machines?

[fnorkn 2]

This one is new for me: I only saw sparks when plugging in the USB cable.

Perhaps check with Ultimaker support? Could be there is 24 volts on the frame.

The white plates have a small layer of aluminium underneath which conducts electricity....

[gr5 2,069]

Is it AC or DC? AC power vibrates your muscles like a buzzing. It's what comes out of your house power socket.

DC you can't feel unless it is thousands of volts. Caused by static electricity which could come from any moving parts (like the printer - it moves).

If it's AC then it's easy to measure with a volt meter. For example you may have bad wiring in some of your home or work power sockets such that some are wired backwards. You could put one end of the voltmeter on a ground like a metal water pipe and the other on various parts of the Ultimaker. If you get 200 volts then that's a problem and try plugging it into other outlets or call an electrician as your power outlets may be backwards.