LCD only works with USB connected

I have just built a couple of machines and they are working well.
Added LCD controllers to them and used a computer connected by USB to control the printers.
I wanted to use the stand-alone feature of using the LCD controller and it worked fine, until I disconnected the USB from the computer.
The LCD powered down as if it was getting it's power from the USB connection.
I have built printers before and not had this problem, they have worked stand-alone without a computer connected.
Not sure why these two machines are dependent on the USB, maybe I have missed something?

Using Arduino Mega, RAMPS 1.4 and Reprapdiscount smart controller.

Had the same problem after a short on the 5V rail coming from the arduino.

Please check the output of the voltage regulator on the arduino.

My original RAMPS had this issue - The diode was installed, but the Arduino was not getting power from the 5 amp rail. I took a barrel connector and a short length of wire, dna making sure I had the right polarity, I twisted the short wires together with the power supply wires going into the 5 amp rail, and I plugged the barrel connector into the arduino barrel connector. It worked well. That board has since died on me for other reasons, but this was never an issue again.

Hello,

I've got the same problem with a Panelolu2.

I have an extra 12v output on my power supply. Isn't it possible to power the Arduino with it ? If yes, will it still be possible to use USB sometimes ?

Thanks

Arnaud

I'm basically feeding 12 volts from my power supply right into the Arduino, and I use the USB connection all the time.

you can set up a ground loop between your computer and your arduino if you dont power both from the same circuit. the AMS1117 (5v regulator) can easily die from shorting +5 to gnd (been there, done that) and may also get burnt with a ground loop. you can order qty 10 AMS1117 5V on ebay for $2.00. they come in handy, course you need to know your way around a soldering iron

@ jbernardis : so basically, you simply connected your barrel connector to the power supply and it works ?

Actually, I'm not sure I don't have a problem since when I plugged a universal adapter on the Arduino (12v, + on the center), the LCD screen blinked without nothing written on it. I don't know what could be the problem...

(sorry for being so ignorant :s)

Edited 1 time(s). Last edit at 03/18/2014 05:43AM by ufab.

Quote
ufab
@ jbernardis : so basically, you simply connected your barrel connector to the power supply and it works ?

That's exactly what I do.

Regarding powering both from the same circuit, that's not quite a correct statement. You need to make sure that you have a common ground, and since the USB cable carries ground, this should not be an issue. By way of the arduino and the USB cable, your PC, Arduino, RAMPS, and power supply all have a common ground.

Ahh. your PC PSU may not have the same reference ground as your printer electronics PSU might, especially if both are grounded to AC.

If your PC's DC ground rail is some voltage different from the AC ground (eg: 3V), while your Printer PSU has a different voltage difference (eg: 1V) between AC and DC ground, then you can run into trouble when you plug in a USB cable.

The "loop" here is that AC ground is common between both devices. Your DC grounds are then different, and then you're shorting them using the USB cable's ground/shield.

Note: This is one of the reasons I deplore the practice of tying DC ground to AC ground on block-style printer PSU's, as it's not always common practice on PC's. You need to test your PC first, before you do something like this IMO. It's also an annoyance with almost all the Arduino form-factor devices, that the USB shield is connected to DC ground (when it doesn't have to be - it should be jumper selectable).

I didn't realize that. Do you think that might be a factor in why the LCD displays periodically show garbage? It's been attributed to "static", but I've never been totally convinced of that.

So, is it a bad idea to connect the extra output of the PSU to the Arduino ?
I think pretty ridiculous to have to connect a USB charger next to the PSU in order to power the board...

ufab: It should be fine to do that.

Just note that the standard design of RAMPS has the power routed through a diode internally, so obviously something is wrong if this isn't working. That may mean you haven't populated the board with this diode (as you're using > 12V), but it could mean your Arduino Mega OR your RAMPS board has a fault. Running direct power may bypass the fault, or it may make the fault worse. You will need to determine any associated risk.

PS: Basically, when something fails, it's operating outside it's design envelope (meaning, we have no or little data on how everything will behave in this situation). We can usually only offer guesses as to what you can do to work around it, as not everything fails the same way.

Hi, in the italian section we got same problems on LCD going off. I'm talking about powering with 12v and the D1 mod. We found out it is a broken line from D1-1N4004 to AM-VIN, seems a common fault in the board production.
Take a multimeter and check continuity between those point. If so just bridge.

Edited 1 time(s). Last edit at 03/23/2014 03:08PM by Gordie.

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---- "Let me make my move" ----

Hi, I am using Prusa i3, Arduino Mega2560 with Ramps 1.4. D1 diode was installed and printer was working stand alone with LCD Controller and SD card.Recently my Arduino board was damaged, replaced with the new one. Now LCD is powering only from the USB and it is not powering through Ramps connection. But even now also it is capable of printing with the SD card (Powered through USB )
Now LCD (Full Graphics LCD Controller) is not powering without USB connection, even I have replaced the Diode D1. Can anyone suggest to get back my printer to work as stand alone.
Thank You.

Edited 1 time(s). Last edit at 11/03/2015 02:02AM by Kana Padmaja.

Quote
Kana Padmaja
Hi, I am using Prusa i3, Arduino Mega2560 with Ramps 1.4. D1 diode was installed and printer was working stand alone with LCD Controller and SD card.Recently my Arduino board was damaged, replaced with the new one. Now LCD is powering only from the USB and it is not powering through Ramps connection. But even now also it is capable of printing with the SD card (Powered through USB )
Now LCD (Full Graphics LCD Controller) is not powering without USB connection, even I have replaced the Diode D1. Can anyone suggest to get back my printer to work as stand alone.
Thank You.

This is an extremely common issue with Arduino/RAMPS and I have responded to similar questions several times, for example here [forums.reprap.org].

I don't understand why this hasn't been listed as a known issue on the RAMPS wiki page.

Edited 1 time(s). Last edit at 11/04/2015 04:07AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Facing the same problem, Could you Please show the picture or something, I am dumb when it comes to electronics....

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Dictator at - www.AgroEngineers.com
Creating - [www.LionBeast.com] - 3D Printers

See [reprap.org].

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].