Yesterday during a print, the printer just stopped working and all motors and fans stopped. My printer is a Graber i3.

Just before that I saw a flare coming from somewhere in the extruder or from the power supply, I couldn’t actually see.

Checked the voltage coming into the RAMPS and it was 0 V, checked voltage coming from the power supply, also 0 V. Checked the voltage coming into the power supply and it was 217 V... that’s okay, the power supply is switched to 220 V.

Today I tried further troubleshooting, by connecting the power supply to 127 V and having it switched to that voltage, before that I disconnected the RAMPS cable in case it was shorted. The result was the power supply did not work, the voltage coming from it was 0 V.

Got in contact with the manufacturer since the printer is brand new and he is sending me a new power supply, but I do want to try to find the root cause of the problem, so I started looking for shorts in the RAMPS, hotbed is okay, no continuity. Neither of the other connections have shorts, until I got to the hot end heating cartridge, in this convection I found 5 Ω resistance between phases. This was at first no surprise because it makes sense since it’s a heating element, but wanted to make sure, is it okay to have this resistance in the cartridge?

Do you guys have any other suggestion for troubleshooting or possible root causes for this issue?

UPDATE 02/OCT/2019: I decided to open the power supply, so maybe I could fix it and have it as a back up. First thing I see once opened, the fuse was blown! So I replaced it, since it is soldered and it is a 8A 250V 3x10mm, which happens to be hard to find... took quite a while. Once the repair was done, plugged it in and boom, another firework happened, this time blowing a resistor and not the fuse.

Conclusion: it wasn’t the fuse, another thing caused the first and second shortening.

  • 2
    $\begingroup$ Have you checked the fuse for the power supply? $\endgroup$ Sep 6, 2019 at 22:36
  • $\begingroup$ Haven’t found an access to the fuse without having to disassemble it. Since it’s under warranty I decided not to open it. $\endgroup$
    – Andrés
    Sep 6, 2019 at 22:49
  • $\begingroup$ Hmmmm ... seems to be the fuse would be user accessible. That's the idea: user blows a fuse; user replaces fuse. $\endgroup$ Sep 7, 2019 at 1:32
  • $\begingroup$ What kind of printer you have? To check for errors in the board, supply it with 5 V via USB. Note that a Heater Cartridge should have an expected Resistance depending on its wattage. 5 Ohm is about what a 12V 30W heater cartridge should have according to e3D $\endgroup$
    – Trish
    Sep 7, 2019 at 9:26
  • 1
    $\begingroup$ @Pᴀᴜʟsᴛᴇʀ2 In many cases, that is definitely not the idea. The fuse is designed to blow if there is a malfunction in the power supply. If you replaced the fuse, the fuse would blow again soon after since the power supply is malfunctioning. Since the power supply is not user servicable (i.e., the user cannot resolve the malfunction themselves) having the fuse be replacable is pointless. $\endgroup$ Sep 7, 2019 at 9:57

1 Answer 1


I would expect the root cause to simply be the power supply itself.

5 Ω is a reasonable resistance for a 12 V / 30 W heater. It seems strange that you are not seeing continuity in the heated bed as this should also have a low resistance (since it's a heater as well). This might be worth investigating further, but I think it's more likely the power supply itself is the cause (and you simply made a measurement error).

  • $\begingroup$ the most common fault in a power supply is that one of the capacitors has a short. $\endgroup$
    – Trish
    Sep 7, 2019 at 10:50
  • $\begingroup$ Hi, checking further found the resistance of the hot bed to be around 10 ohm. $\endgroup$
    – Andrés
    Sep 9, 2019 at 0:14

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .