Trouble starting up with headless configuration

Does anyone have some instructions for hooking up the PS-ON pin? I'm trying to use the PS-ON pin on my RAMPS board, however I've run into an issue. When I flip the switch on my PSU, nothing happens. Its not until I "jumpstart" the system with USB power will the PSU stay on. I've hooked the green wire from my PSU to the PS-ON pin, and the purple VSB wire to the 5V pin next to the PS-ON pin, however that doesn't seem to adequately power the Arduino. I have a feeling I'm missing something obvious, any suggestions?

Machine Config:

• Prusa Mendel i2
• RAMPS 1.4
• RRD sdRAMPS
• 16x2 LCD
• Marlin firmware
• ATX psu

I think you are supposed to connect the 5vsb to the vcc pin rather than the 5v pin, Not sure if that would make any difference though.

Are you getting 5v on the 5vsb line? Do you have a ground connected to the main power connector?

I had a similar setup toy you so it will work

Works like a charm, thanks. After looking at the PCB traces, it looks like the pin labeled 5v only goes to the servo pins. This seems like a misnomer to me because hobby servos will accept anywhere from 4.7 to 6 volts (some even go up to 7.2v). Maybe this could be better labeled in future versions of the board.

Great, glad its sorted. and yes it is a bit misleading. You could feed any voltage to that pin without effecting anything else, which I didnt realise until you pointed it out. Could be helpful

Wait a minute,

Isn't the VCC supplied by the Arduino?

By hooking up an external 5V source, are you not now backfeeding through the Ardunio?

Right from Arduino's Website
5V. This pin outputs a regulated 5V from the regulator on the board. The board can be supplied with power either from the DC power jack (7 - 12V), the USB connector (5V), or the VIN pin of the board (7-12V). Supplying voltage via the 5V or 3.3V pins bypasses the regulator, and can damage your board. We don't advise it.

Do you have DIODE 1 in place?

Quote

When I flip the switch on my PSU, nothing happens

.

It's not suppose to. A command in the GCODE turns on the Power Supply.

Edited 2 time(s). Last edit at 05/13/2013 09:16AM by ShadowRam.

That is a good point. I forgot to mention that.

I think marlin turn on the power supply as soon as it is starts up by default.