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Hey everyone,

I have finished building my printer and so far everything appears to be working without issue. I have now begun to add in the raspi3 addon kit to the printer to allow for remote printing using OctoPrint and I believe I have it working just fine now. I am trying to get rid of the external power supply for the Pi and was wondering what people have been using to achieve this. After a little research it appears that I might be able to use the "5V Aux Out" near the Heat0 connector and powering the Pi through the GPIO connector.

Looking at my Rambo though, it seems the 5V solder pads are filled in on the bottom of the board and would not be able to accept a connector terminal. Is this something I can remove safely and has anyone had any experience powering the Pi this way? I could always use an external power supply but it looks terrible. What have other people been using to solve this or is there a way I could tap into the 12V rails of the power supply its self with some measure of safety as to not overvolt the Pi and blow either it or something else?

I was able to get a 2-pin JST connector onto the +5 and gnd pins of the "Analog" pin header right next to the display adapter board to power mine.

I didn't buy the kit because I already had an r pi 3 sitting around looking for a job, so I don't know what they recommend.

Here are some options from my perspective, with the caveat that I don't have a V3, or a raspberry Pi on my (heavily modified) V2.
First option: heat the solder points from one side and insert the connector from the other once the solder liquefies. Downside is you need a third hand fixture and possibly a friend.
Second option: Take power from the V-ref pin as Noircogi mentions. Downside is that it may destabilize the reference used for the ADCs.
Third option: Buy a 12v to 5V regulator. These are available from ~2$ (Don't trust that one), to 20$, with the best option for you being something like this. Downside, most cost in parts
Fourth option: Wire a USB power transformer in the base to the mains voltage and try to figure out how to get it up to the top. Downside: involves working with wall voltage.

i took a voltmeter and measured leads on the rambo until i found a nice 5v out, works great now. i can take a pick of my connection points if anyone is interested.

pswindler wrote:i took a voltmeter and measured leads on the rambo until i found a nice 5v out, works great now. i can take a pick of my connection points if anyone is interested.

Yes please

In addition to the analog header, there's +5vdc on the extra endstop pins as well.

The jury is out on what current you can get from each of those places, though. If anyone is better informed than I, please post what amperages you can draw from where for posterity.

The LM22675 buck converter that provides 5V on the Rambo board is rated to supply 1A. I can't say how much the Rambo requires for itself, however.

I'd think if you are adding a touchscreen to your raspberry pi, that one amp is cutting it close.