Hot end and stepper motor issue.

[pjfossee]

Thanks for the reply Alibert. I appreciate the clear explanation. Learn something new everyday! Anyways you were right that the PSU was over-stressed. Well its actually an ATX PSU that can push 49 amps supposedly but I think my issue was that I did not have enough 12v and ground wires going from the PSU to the 5 amp rail on the RAMPS board. I thought 2 20AWG wires per 12v and ground would be enough, but I guess it wasn't. I'm using 4 20AWG wires now and am having no issues. Thank You for working through this with me! Quick question - what does the 11 amp rail power. Just the heat bed? If I am using a relay then can I expect that there will never be the whole 11 amps drawn from that rail? Thanks again!

[printbus]

... what does the 11 amp rail power. Just the heat bed? If I am using a relay then can I expect that there will never be the whole 11 amps drawn from that rail?

On RAMPS, the 11-amp input *only* sources power for whatever is connected to the D8 output, which is usually the heat bed. If you're using a heat bed relay, D8 would only need to supply a small amount of current to energize the relay. #20 wires would be more than fine for that, as would just adding short jumpers from the 11-amp input to the 5-amp input.