Power for headless printing

Hi,
I made Reprap i2, and it works fine - from the computer over USB.
My RAMPS 1.4 came with D1 and D2 already installed.
I can run test for SD card, and it is aveilable, too.
But when I try switching to headless, i.e. disconnect USB, insert SD card with G-codes and turn on power, nothing happens. I mean, nothing, including no LEDs on Arduino confirming it gets power.
Any suggestions what is missing?
Thank you.

Try it with arduino powered through it's DC input. (7-12v DC)

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Collective intelligence emerges when a group of people work together effectively. Prusa i3 Folger (A lot of the parts are wrong, boring !)

Also, as a first step: even if we forget about SD card reader - why, when I power the printer up, LEDs on Arduino do not flash (as they do if I use USB to power Arduino)?

Edited 1 time(s). Last edit at 02/23/2015 10:08AM by Fizpok.

I thought about it. But
a) I was not able to find any clear instructions, and I am not electronics pro. My power unit:
[www.ebay.com]

b) Diodes are already there, so I'll have to remove them. Am I correct: I can not have power to 5V AND diodes?

The RAMPS board takes the 12V power, but the arduino (The "computer" controlling the RAMPS board, and the SD card reader) is powered via the USB socket, or else the power socket on the Arduino.

It's like expecting to power on the RAMPS board and expecting that to turn on your PC. give the Arduino its own power, and it'll be fine.

I was under impression, that the main way to go is: [reprap.org]
As my RAMPS 1.4 came with diodes already soldered in, it seemed loical...
Now, if I am wrong, could you please provide instructions / links / pictures on how to wire from [www.ebay.com] to Arduino board, and should I remove diodes in that scenario?

Still hope there is a way to use power from RAMPS...

Also, if I connect Arduino via barrel jack (is that what was suggested?) what will happen when I plug in / out USB?

Nothing particular will happen. First check if the arduino DC input (barrel jack) works.

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Collective intelligence emerges when a group of people work together effectively. Prusa i3 Folger (A lot of the parts are wrong, boring !)

Which brings us back to 3 questions:
1. Could someone comment on using the scenario with diodes, as they are already there?
2. In order o connect power to barrel jack, should I remove diodes first.
3. In order o connect power to barrel jack, AFTER I make sure it works from wal-mart power supply, how do I connect to the printer's power supply [www.ebay.com]. I mean, having both this one and wal-mart one is kind of stupid...
I have VCC / 5V on RAMPS, next to reset button. Is that the place I connect from power supply?

Edited 1 time(s). Last edit at 02/23/2015 12:48PM by Fizpok.

The problem is solved... In a sort of intimidating way. It is possible to do headless printing, using power from RAMPS via diodes, but... to prove it, I had to replace Arduino with another one.
So, the first one was damaged.
And the question now is: what can be damaged, so that printer works via USB, and power not available from RAMPS via diodes... And how to prove it... And how to fix it...
Please help.

The diodes are there (As I remember) to prevent inappropriate voltage power from being fed back to the arduino. Leave them be. There is no voltage regulation on the 5V arduino rails, so this should be fed from a regulated supply. The barrel jack has voltage regulation on it, so it can be fed from your 12V supply, so long as you have an appropriate adapter. Much easier to just use this.

You COULD use an ATX power supply, and use the 5V from it, and the 12V for the RAMPS supply, but it shouldn't be necessary. Go look on the arduino forums, and there are plenty of people using 12V to power the arduino, just not on the USB jack. (If you power the arduino separately, the difference will be that it doesn't power off if you unplug it. It should still coonnect to the PC properly.)

So:

1. As I said. leave them be.
2. No
3. I don't use any of the 5V stuff on the RAMPS, except where it's connected to the arduino. Power the arduino from it's power jack.

Thanks. But - see my last post. By replacing the (presumably, damaged) Arduino with an identical one, I managed to get it working while doing no extra wiring. That's why I was so persistent when asking about the "diodes" scenario.
So now I'd like to know, what might be broken on the (dameged one) Arduino, so that it does not see RAMPS power...

Edited 1 time(s). Last edit at 02/23/2015 01:49PM by Fizpok.

It will probably be the voltage regulator.

Power through the usb port bypasses the regulator so its been working for you on the pc.
But when you power through ramps from the 12v the regulator isnt working and providing the 5v you need.

I think you can fix it if you look out for the instructions on the net.
I must admit i uavnt bothered when ive trashed mine as ive mainly used cheap arduino megas.

Gordon

What keywords and terms should I be looking for?
Also, as I broke ate regulatr, I guess that particular Arduino still can be used if I provide power from power supply.
Which brings the question: how? I am (again!) looking for exact wiring instructions, I guess...

Thank you for the answers. It helps a lot, to know that you are not struggling alone against that piece of alien technology

Ive just searched for "arduino mega regulator fix" and found loads of examples.

Gordon

FizPok

Check that D1 is in fact soldered in the right way round IIRC the stripe should be towards the power connectors on the Ramps (It has been known for them to be put in the wrong way which means that they cant power the Arduino)

HTH Doug

dougal1957:
Checked. It is the right way.

As I said, there may be a way to feed power to a damaged Arduino from Power supply.
Questions for that case:
1. Should I remove diodes
2. What is the schematics of wiring. As I am not a pro, I am looking for details, like "from this pin on Arduino (or RAMPS, remember, RAMPS still sitting on top) to that contact in power supply unit".

1: no.

2. Power to the Arduino Mega 2560 can be wired to the DC input jack, recommended voltage is 7-12VDC. Input voltage limits to this jack are 6-20VDC. Your 12V power supply that you are using for your RAMPS can be connected to the DC input jack on your Arduino.

I received one that was messed up too, I just removed the diode to be safe and ran 5v to the Servo plug, was the safest way for me since I had some RC servo wires and the power pin is in the middle so can't screw up and burn anything up if you plug it in backwards.

I did this because I was planning to run more than 12VDC to the power plugs. I am using 14VDC not crazy high, but more than what RAMPS with diode installed is rated for and gives me the little extra to heat up the bed quicker. Another advantage is nice clean power for the LCD display, mine used to flicker a little when the heaters where warming up.

Thank you. Just to be clear: DC input jack is the same as barrel jack?
And I DO NOT have to disconnect it before plugging in the USB?

Edited 1 time(s). Last edit at 02/24/2015 02:57PM by Fizpok.

So the power jack versus barrel jack same thing. Its the power plug on the side of the board. 7-12VDC max.

Link to picture of all the pins

This is just my opinion and having much caution. The Real brand name Arduino is suppose to filter it so that extra power can not backfeed into the USB cable and cause issues with you computer. I bought a cheaper version of the board so using that power jack on the side at the same time as USB not going to happen for me; never know when a compenent may fail and backfeed 12VDC into the USB cable.

So my workaround was to get a dedicated power supply just for the board that is 5 VDC and use the pins on the Ramps board marker "SERVO" 5V and GND. I set the power to just under 5VDC. I can safely use USB and external power at the same time.

A genuine Arduino (What I have) will tolerate up to 20VDC, though 12VDC max is recommended. A knock-off, all bets are off. It SHOULD NOT feed back power to the USB if fed from another source, but it bears testing that does not happen. I recommend that you do test this by checking the +V and GND pins on a USB cable plugged into the arduino before plugging the cable into the PC.

Feeding power to anything other than the DC input (barrel) jack on the arduino is discouraged. It should work fine anywhere on the 5V bus, but remember that voltage regulation and filtering ONLY happens from the jack side of things, and if there is any irregularity in the 5V fed anywhere else, bad things can happen. if you're sure of your power source, fine, but do not use an unregulated supply to anything but the DC input jack.

For my one and only experiment with headless printing, I used an old wall-wart that I had lying around that provides 9VDC, and fed that to the DC input jack. It worked fine. Feeding power to my RAMPS board does not power on my arduino, and I have never had cause to try to pull 5V power from anywhere on the RAMPS. Frankly with the Chinese special PSU that's providing 12V to the RAMPS, I don't really want to trust that power for things more sensitive than motors and heaters.

This is RAMPS schematics, not Arduino.

So, to finalize:
I take the PSU. It has 2 COM and 2+V, I connect them (which ones? and what the dif. between COM and another COM and +V and another +V) to the Arduino's barrel jack (which line goes to center and which one to the outer contact of a jack?).
Then I connect the power and test the voltage at USB cable, it should not be more that (what is the limit?)

This is very very good!

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интериорни врати

The PSU should have 2 +12VDC outputs, and a couple of commons (Typical of the LED strip PSUs that a lot of the reprap kits come with) -- both of which should be connected to the RAMPS board, one on the high amperage input and one on the lower. IIRC, high amperage feeds heat bed, lower amperage feeds motors and the like. the lower amperage one I also have a 4 pin PC supply connected to to power fans to that one, which I would also feed power to the arduino from.

The RAMPS servo control I was pretty sure just connects to a set of pins including the 5V bus on the arduino, so you would be in fact connecting power to the 5V bus bypassing all regulation on the arduino board. I could be wrong, but I did not think that the RAMPS board itself had 5V power regulation on it.

Anyway...

Yes, Connect the +V to the centre pin of the power jack, and COM to the outer. It is (I believe) a standard 2.1mm jack, so it should not be difficult to obtain.

And yes, Check that you are note getting backfed power on the USB of more than 5VDC. It really should not backfeed at all, not even 5V. If you are getting more than 5V on any 5V bus location on the arduino, there is something seriously wrong with its power regulation section, and you should not use the power jack at all.

Thank you very much.