I have a solidoodle 3, ive upgraded the heated bed, and therefore i am using 1 atx powersupply for that, and 1 seperate atx powersupply for the printer itself.

The heated bed is in no way connected to the printer itself, i am using an external thermostat for it.

But when the thermostat's relay clicks on and off, the printer will lose connection with my computer, because of the spike.
The powersupplies used is both  15A, so i think it should be enough.

So i thought i would solve the problem by using an UPS on the printer, that was a fail, when the relay clicks on, the communication is lost.

I tried to switch over the ups on the heated bed, still a nogo.

Any advice?