MK2 Heat Bed causing power to shut down

Good Day.

I am pretty new with this whole 3d Printing thing and have finally assembled my first Prusa i3. The problem that I had started when I added my MK2 Heatbed to my RAMPS 1.4. Everytime that I attampted to turn on the bed to heat it, my ATX power supply would shut down. After going through all of the posts on this issue and troubleshooting everything that I could. (shorts, 5V load, different PS, marlin changes, etc.) nothing worked. Finally at the end of my ropes on this issue I found the problem. My ATX power switch wire (the green one) and the 5v "standby power" (The purple one) were connected to the ATX power on pins on my ramps board, and, working quite well to power my unit on and off through the LCD, were causing the problem. It seems that something was happening to loose ground on the switch wire(?) and causing the Power Supply to gracefully shut off. After removing the wires from the ramps and just grounding out the green wire for the ATX PS, Everything is working GREAT......But No ATX Power Control.

Anyone have any idea what kind of problem that I could be having with the ATX power attached to my Ramps board?


-clanhenry

As you say you are using the 5vsb from the atx supply, have you removed the D1 diode that runs under the x and y drivers? It feeds 12v to the Arduino voltage regulator. Having the diode in and supplying 5v can cause odd things to happen.

Also I found that you sometimes need a resistor between the green wire and the ramps power pin. I used a 4k7 if I remember correctly. It was very difficult to reliably control the atx supply without the resistor.