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reprap full discount graphics controller gets garbled sollution ?

Posted by gutendorff 
reprap full discount graphics controller gets garbled sollution ?
November 04, 2022 06:19AM
Solved ?! I have seen many posts about this. But none of them solved the issue. I have 3 printers running on marlin 2.0.7 and ramps 1.5 and 1.6 of course it a mega 2560 running the show. The issue is that with the almost original lcd everything works without delay for the lcd driver. So printing from SD card works flawlessly, with the older discount controller, but the newer Controller need delay and the also crap out after a while, with garbled lcd and halts the print within minutes. Printing with usb works perfectly !!!!!!!!!!!!!!!.
I measured the 5v and it it still 5v when this happens. Here lies the solution because if the usb cable is connected to a GROUNDED pc, It will work w/o problem. So my conclusion is that it is and grounding issue and simply using the usb cable for extra 5v input and grounding the mega 2560, will solve the main reason for the lcd wanting to crap out ?
If i connect the usb cable to an ac adapter the interference issue is not solved due to the ac adapter often is not grouded in sweden,and as we do not have a dedicated zero phase in our sockets and the is no ground on the smaller ac apdaters. connecting is to a big PC where the ground is connected to both psu and cabinet will work. We should forbid ungrounded psu:s forever because the cause all sorts of strange problems. Either that or bolt on ground screws everywhere and connect to a dummy ac plug with only ground connected. But even that wont work in all cases. Because it did not work for my DIY milling machine. And for those who like audio and wants to fiddle around with 12 volt car amplifiers, and connect it to a tv or any other source knows, you will encounter ground noise in the audio signal, and is is difficult to solve. The 3d printer with the issue is a Makerbot replicator 2x. The psu is grounded though, but still we have a problem with interference. i did use 10 nf caps to filter out noise going to the thermistors. But simply using a grounded usb sorce always works for any chinacrap knockoff lcd !!! just plug it in and the issue is solved forever ? I wish that others would have found out beacause i was almost suicidal before i discovered this. Easy fix !
Re: reprap full discount graphics controller gets garbled sollution ?
November 05, 2022 02:07AM
It's well known that attaching a graphical LCD overloads the 5V regulator on the Arduino, causing it to overheat, reduce its output voltage, and often fail. Connecting USB provides an alternative source of 5V power.

12864 display modules vary in the back-light current they draw. Some have a zero ohm back-light resistor fitted.

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].
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