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Magical blue smoke

Posted by Redledr 
Magical blue smoke
November 18, 2015 11:10AM
So yesterday I got my kossel up and running. 450W ATX PSU, I have been using that power supply to make dry runs on the kossel for about a week, waiting for all my extruder parts to arrive. Anyways, I am so green to the whole delta printer scene. I was printing yesterday with filament for the first time, but not the first time I have had a dry run with a heated hotend. First print went great, second thru fourth were sketchy because of a clog and the fifth print tripped my power supply after it homed and heated the hot end. PSU was pronounced dead at the scene, that's fine, it was old. Hooked up my 650W corsair the same way. And at first, the hot end would not heat, at all. Had no problem with the 450W PSU with 24 amps, but the 650W has 54 amps. I smelled the burnt board smell, but no smoke and it was very very faint. So I unplugged it and left it, about 2 hours later, hooked the usb up to it and it would not turn on, mind you when it smelled like burnt board, it was still on and functioning. This morning on the other hand, hooked up the PSU and smoke...I have no idea what happened. I ordered another ramps 1.4 and mega 2560, but I still need to know the cause. Is the 650W amps too high for the board? I used the PCI-E 4 pin, not the CPU 8 pin, wired the black and green on the motherboard 24 pin. Nothing else changed, worked perfectly.
Re: Magical blue smoke
November 18, 2015 11:54AM
... the stated current on the PSU is only the 'specific capability' - it's the hooked load, what's drawing the current regarding to Ohms law.

So when something burnt, then it was either built with too low internal resistance, shorted, or wired wrong ...

Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]
Re: Magical blue smoke
November 18, 2015 11:56AM
The problem is more likely to be that something (either hot end or heated bed) is taking too many amps, not that the PSU can supply it.

Or to use a metaphor: it's the faulty tap that causes the flood in your house, not the big reservoir at the end of the pipes!

I'd check for a short circuit on the hotend or the wiring to it. If you have a heated build bed, check that also. It's likely that a problem with a heater element made the heating circuit draw too much current which would have damaged the electronics.
You need to check for this problem before powering up the new electronics or they'll likely be killed again.

Re: Magical blue smoke
November 18, 2015 12:13PM
That sounds more reasonable, I was moving around the hot end and the wires could have broke and grounded to the end block. I'll check when I get home and see what I'm pulling. Is it normal for hot end cartridges to short out board or short out period? I wouldn't think something so small could be the straw that breaks the camels back, or in this case the PSU. But say it did, and the wires are now completing the circuit instead of going through a resistor, and all the current instead of being absorbed is now going straight back into the board, that would be the cause of it smoking this morning? I did not smoke last night when the hot end cartridge quit working. But it did this morning, so maybe something moved and that's what happened? I'm not electrical engineer and I am definitely new to this whole circuit board deal.
Re: Magical blue smoke
November 18, 2015 01:12PM
... depending on the location of a shortage it will overpower the involved MOSFET's, voltage regulators or I/O-pins - either of them can produce 'magic smoke' too ...

Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]
Re: Magical blue smoke
November 18, 2015 02:43PM
Where exactly did the smoke come from? Is there any sign of charring?

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

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Magical blue smoke
November 18, 2015 05:53PM
As said.
As long as your power supply can output more amps then needed, then your good.
The items will only pull as much amps as they need.

Now on to why it might have messed up.
It sounds kinda like a wire came out and fry the board.
It could of been a endstop that ground out the 5v power, the hot end or heat bed wires could of touch (pos to neg) and blow out the board.
The best thing to do is get a voltmeter and check all the wires for shorts.
Re: Magical blue smoke
November 18, 2015 06:29PM
Well I just got home and went and looked. The Mega board is perfectly fine, powers up and resets. I took the ramps shield off and the D10 MOSFET connection on the back are toast. And the heat cartridge was twisted and the wires fused at the base. So I found my problem!
Re: Magical blue smoke
November 19, 2015 04:17AM
.... and the D10 MOSFET connection on the back are toast....

Should not happen - there are the yellow polyfuses which should protect all of the Board
As far as I can remember, D10 is working on the 5Amps Input - should never be a Problem for the MOSFET and/or the Connections on the back.

Maybe there was a Short from the 5Amps to the 11Amps Input? - I've heard of some chineese RAMPs-Boards, that had some Problems there.....
Re: Magical blue smoke
November 19, 2015 11:29AM
That's what happened, the heater cartridge fused the connections and caused a very bad short it seems.

Re: Magical blue smoke
November 20, 2015 02:45AM
Sorry - your Pictures are to small to see anything...
Re: Magical blue smoke
November 20, 2015 04:04AM
Try clicking on them...
Re: Magical blue smoke
November 20, 2015 04:56AM
Clicking did not work before - now it's working...


I can see you did solder it yourself...
Question: Did you use electronic soldering tin with resin core???

Important: Clean up the board!!! - I can see soldering tin on many places it should not be... example: left, near bottom - but many small soldering tin squirts all over the board..

Why did you solder it yourself? - you can get it for less than 5 Bucks on Aliexpress with free shipping...

EDIT: Just compared with RAMPS 1.4 Documentation:
there was a via at the burnt place.... I think it was the ground via for the LED - so your hotend did not turn off anymore (when MOSFET was turned off), all the current went throu the led via which got to hot and burnt away...

Edited 2 time(s). Last edit at 11/20/2015 05:06AM by Sir_Death.
Re: Magical blue smoke
November 20, 2015 10:17AM
Well that is interesting. I have a new board on the way, ordered it two days ago. And the board was not soldered by myself, but that one copper joint that burnt I did re-solder. But the board was just fried, bubbling on the silkscreen and such. But I have a new ramps on the way along with a couple new heater cartridges. Also switching from a .3mm nozzle to a .5mm nozzle to run with my 3mm filament.
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