Why is the printer not earted?  

New Member

Hello everyone,,

I mustn't be the only one getting static shocks from his printer now and then. But sometimes more than once per day.

I remember from assembly (bought the kit version) that there is an earth connection between the power outlet to the SMPS's ground, but then, it stays in the power supply. I don't see a connection between the PSU's ground and the machine. Also the machine powered by a floating power supply (aka V- is not connected to the earth), why? I find it strange, specially considering the machine as long cables connecting directly to sensors.

Today, I checked up the machine, saw no reason not to, and connected an alligator clip from a power socket's ground pin to the frame of my printer and everything was good, used the printer normally and all systems worked as intended.

Why isn't this standard? Surely Prusa Research must have a reason not to do this, considering there is no cons, and makes the machine safer and more reliable (and you don't get electrical shocks touching the metal 😉 )

Posted : 31/03/2020 1:40 am
Estimable Member

I get small shocks that actually reset my MK3S from time to time. Can you share a pic of where you made the connections?

Posted : 31/03/2020 5:52 am
Estimable Member

Its too late for me to look tonight, but I believe the power supply is grounded to its metal case, which is screwed to the frame.  I'm 99.99% positive that you can measure 0 resistance between earth ground pin on 120VAC PS and the front bolt securing the PS to the frame.  I know I touch that screw to discharge static before touching the LCD....but i need to ask bobstro about his grounding idol and if he ever made it happen.

Is your printer grinding? Bearings squeaking? Motors smoking?
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Posted : 31/03/2020 8:36 am
Noble Member

You might want to read this thread from a year ago https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-hardware-firmware-and-software-help/grounding-the-printer/#post-122788

Posted : 31/03/2020 9:28 am

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