Printer only works when USB connected

Hi,

I recently moved to a new place, therefore disassebled my kossel, now after putting it back together again, found myself with display issues. Mainly, the Printer will only work when a USB connection to the computer is established. The hotend and electronics fans are hardwired to the power supply, they turn on the moment I turn on the Power, but the display only lighty up when connected to USB. Also, when USB is interrupted mid-print the print stops. after USB reconnection the printer restarts, so electronics were shut down. Also, the display is flickering constantly.

So I guess this is a Power Issue, but I use the same computer power supply as before, and the electricity supply seems to be okay, because none of the laptops and other devices are showing any kind of trouble.

Any of you guys can help me?

I'm using Ramps 1.4 and Arduino Mega, with a RepRapDiscount Smart Controller.

Looks like the 5V regulator (1117) on the Arduino board is damaged. (This happens easily e.g. when plugging in mechanical endstops the wrong way - as this will cause a short between 5V and GND as soon as the switch is closed.)

thanks for the reply, enif.
okay, I did plug in the endstops the wrong way, I remember doing multiple m119's and cursing about bad documentation of my supplier.
Is there any way to fix this or can I just get a new Arduino Board? Also, are there other errors to be expected?

You can simply replace the 1117 voltage regulator which is near the power jack of the MEGA.
If you don't feel like soldering, you can also feed 5V from some other source (may be even your power supply has a 5V output) directly to the VCC pin of the RAMPS.
Finally, you can also just alsways keep the USB port connected to either a PC or to some USB type charge adapter.

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Also, are there other errors to be expected?

I would remove the faulty 1117 from the Mega board even if you do plan not replace it - just to be sure that it does not cause any problems, such as sinking current from the 5V side or passing some unregulated voltage from the 12V side to the 5V line.

The simple fact is that you cannot add a graphical LCD to Arduino + RAMPS without overloading the 5V regulator on the Arduino. There are one or two new threads every week from users who have wired up this combination and are having problems as a result. See #1 at [reprap.org] for workarounds.

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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].

Thanks guys! first thing I did was order a new mega board, to be on the safe side. Now for saving this one.
So If I replace the faulty 1117, I should replace it with a stronger one, right? which one should I use?
Also, How do I recognise an Arduino variant with a more powerful voltage regulator? It mentions the taurino, are there other versions / where to find information on this?

As you have been using the same printer with the same non-graphic display without problems before moving to the new place, I guess that it was the short from wrongly connecting the endstops that caused the 1117 to blow. So simply replacing it should probably be okay.

But of course dc42 is right, reducing the 5V power drawn by the 2004 display would be much safer, e.g. by lowering the backlight current (replacing the 100Ohm RBL resistor by one with a higher resistance), or connecting the backlight to 12V instead of 5V as described in the wiki.

Okay, then I'm gonna look for a new 1117, as well as for options on Backlight connection.

As a workaround, I connected the printer's USB to my phone's charger, which seems to provide enough energy for the display to stop flickering.

thanks again for your help!