Smoked Power Supply (it's kinda like smoked salmon)

issue Issues power_supply PSU smoke

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Hello Thingiversers,

I have had my A8 Clone for 4 years and printed hundreds of hours. Finally, I believe I somehow fried my power supply. Hopefully my thoroughness (longwindedness) anticipates questions more than it scares away readers...


  • Alunar M508 Kit
  • AC 110/220V (set to US 110V)
  • DC 12V
  • Bed power supplied by MOSFET
  • 12V heating element in E3D V6 clone
  • 12V PC fan cooling PSU
  • Custom PSU mounting bracket (PSU sits horizontally and of course collects lots of dust, "yikes" now that I think about it...)

Happenings and occurrences:

  • My printer had been sitting plugged directly into the wall (was not plugged into a surge protector as it usually is) with the switch powered off for a few weeks as it usually is during busy college semesters. I have used it a little within these past few months.

  • Earlier the same day as the incident, my apartment experienced a brief power outage, lasted 30 seconds or so.
  • Roughly 2 hours later I set up to get a print going and flipped the power switch "on".
  • If I remember correctly I believe I heard my printer power on, noticeable by the sound the heatsink fan turning on (if I recall correctly).
  • My PSU fan did not immediately spin to life like usual, but jittered a little in place, possibly made a small unusual noise, maybe a little whining.
  • Not thinking anything of it, I spun the blades manually to get it up and going (pretty sure I would have spun it in the "correct" direction), but it did not maintain any powered rotation.
  • Almost immediately after that, I saw {a small amount of} light-grey smoke emanat{ing} from around the top and front side of the PSU - the side closest to all the wiring - from between some perforations in the metal casing and the gaps in my printed mounting bracket.
  • "No-no-no".
  • As soon as I saw the smoke I pulled the C13 power cable out of its respective port to the PSU.
  • All this must have happened in a matter of less than 5 seconds.
  • I went back after a couple minutes (probably waited that long because of pure shock, pun intended [though thankfully didn't actually shock myself :P]) and scanned the exterior with my basic IR temperature gun and found a temperature reading of 2C higher than room temp, again, at the front side near the wiring.
  • I checked the power switch fuse, external to the PSU, looked fine.

That's what I gathered and that's about all I know. My lingering suspicion is that the combination of the power outage and the direct-wall power connection has something to do with it although dust is a possibility as I doubt I've cleaned the PSU and fan within a couple years. The power outage explanation doesn't make a whole lot of sense to me. The printer was off during the outage, circuit into the PSU open.

It's up to YOU to help me find out the issue. Only YOU can help prevent printer fires. I want YOU for U.S. [3DPrinterTroubleShootingHelpAssistance].
I.E. how do y'all interpret this issue and how should I go about investigating it?
I do not presently have access to a multimeter (nor the time to investigate during these last couple weeks including finals) but can investigate fully when I return home and I would appreciate any help I can get.

My aim is to (if practical):

  • Find out the cause so I can set up protections to help keep it from happening.
  • Investigate my printer itself (mainboard, heating elements, etc.) to find out 1) if anything else is damaged and 2) how to keep from damaging whatever parts still work during investigation. (e.g. Think it makes sense to completely disconnect the printer from the PSU to start with)

Supporting pictures:

  • Main view: shows overall setup; PSU bracket has lid removed.
  • Fan top-down view: red sketch highlights where I think I remember smoke coming from.
  • Wiring top-down view: shows my general wiring setup. Has worked gorgeously for the couple years since I last modified it. Yellow sketch highlights roughly the location of the +2C temperature reading.
  • Power cable view: C13 power cable with dramatic focus on wall plug.

Thanks for anything.
-Jonathan Wever

Happy New Year.

I cracked the ol' PSU open and found four burst capacitors. Images attached.
Right above the capacitors there spurted some capacitor guts onto the underside of the perforated metal case, forming some very interesting crystals. Guessing those formed at the time of bursting either because of the charge still stored in the guts or because there was some electricity coursing through the metal case...or both, yikes...
One cap in particular had a small remnant of guts hardened on its top cover, in the X; and after cleaning that off, a very small breach could be seen - shown circled in red.

Seems the PSU was primarily made of Chinesium.

Still curious if anyone has further explanation.
-- Jonathan Wever

It was cheap shit, nothing else to explain :p These are known fire hazards.

She's fried mate! Just replace it as suggested by others. I got a pile of spare modded PC power supplies I used for increased safety and reliability but all my machines are 24v now. Hit me up if you want one and are in the US. My info's in my profile.

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Just replace the PS.
Electronics don't last forever.
Defecation occurs: clean up and move on.

Will most likely do that ultimately but I'm also interested in learning why this happened and what I can do to help prevent it.

Since I left this page up... It's cheap china junk. Those power supplies have almost no protection and are made form the worst components. I have been building machines for over 20 years now and I always start out with a good power supply. Even my 24v Printers use industrial supplies not those average cheapo things you find on amazon and ebay for that reason. They all have over voltage, under voltage, short and overload protections. In the 24v field one like this is something I use a lot and used they aren't crazy priced. In 12v I like PC PSUs for the same reasons, and they have a 5v rail for running a pi and octoprint. See here for some more info on that.

PSM24-360S Enclosure [or other 125x80x125 DIN PSU]
How To Use a PC Power Supply With Your Printer!

Thanks a lot. I'll come back to this in a couple weeks.