My problem is I've bought a 3d printer from china. As usual with consumer electronics the psu is a heap of shit.
I've read on forums you can connect two atx supplies in series to generate 24v instead of 12. HOwever they say you must cut the earth connection. why?
Am guessing the gnd is connected to the earth hence it's then no longer in series
Best Answer
As you can guess, you cannot connect two separate supplies in series if at least one point of them is common.
You know, ATX PSUs' outputs are isolated from mains:
simulate this circuit – Schematic created using CircuitLab
But you don't know that whether the output return path (i.e. GND) of any ATX PSU is connected to earth (e.g. via a series capacitor) or not. If return path is connected to EARTH, you cannot connect these two supplies in series. To avoid the risk of a failure, you should cut EARTH connection. But note that EARTH connection is of vital importance.