Heat plate kills ATX Power Supply

I'm building my first RepRap with the Prusa Mendel kit from MakerGear, and I'm almost done, but whenever I enable the heated pcb with Pronterface, my ATX Power Supply dies and stops powering the machine.

I'm running RAMPS 1.4 with Sprinter and I'm controlling it with Pronterface. I'm powering the machine with an ATX power supply. I have the high and low current lines hooked up to RAMPS just as I've read in the instructions. When I set the temperature of the PCB in Pronterface, the LED on the heat plate turns on for a second, then the power supplies goes out. After waiting a minute, unplugging it, and plugging it back in, the power supply works again.

Has anyone run into this before or have any ideas for what I could do to fix it?

People often write that you need to put a load on the 5V line of the PSU in order for the 12V line to work properly.

So hook up a car bulb or some resistor to a 5V line of the PSU and try again ?

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Most of my technical comments should be correct, but is THIS one ?
Anyway, as a rule of thumb, always double check what people write.

Just tested my heatbed and have the same result. Antec supply says it's good for 15A & 17A on 12v1 & 12v2 but put a 1.2ohm load on it and it dies in the arse. Might try another one.

And it will likely take more than you think on the 5V line to get good supply from the 12V line.

[reprap.org]

My issue turned out to be a wiring fault. Off by 1 terminal. And was pulling 12v to 3v supply.

If you don't have a light bulb or a resistor to put a load on the 5V line, a piece of steel like a paper clip or piece of the spine of a spiral notebook also works. I have my 5V line connected to a ground line with a piece of steel binding wire. If you try this just remember it needs to dissipate heat like a resistor and thicker wire means less resistance, while longer means more. I have mine wrapped in electrical tape to insulate the connection and taped to the case of the power supply.

Also, make sure your power supply can provide enough current to the electronics and the heat bed.

Edited 3 time(s). Last edit at 06/13/2012 07:06PM by MaFraL.

I think a resistor would be better advice. I am curious what happens with this setup. Does the 5v line just sit on current limit the whole time your power supply is on?

I agree that a resistor is likely the better way to do this, I just didn't have any and didn't want to order them and somebody mentioned getting theirs to work with a paper clip. Surprisingly I haven't had any problems with it.