Printer is not starting after assembly, LCD suspected
Hi everyone,
after a long assembly time, my mk3s is not starting ... ;((
The green light on the ensy board works when I turn on the power switch but I can't see anything on the screen. My first suspect would be the LCD cables as there is a slight damage on them, see attached photo. I re-checked the correct fit of the lcd-cables on the ensy board and on the lcd panel itself. I also checked for bended pins. Also the manual mentioned that when moving the extruder that the x-axis motor works as a generator and the lcd might flicker. When I move the extruder, the green light works dimmed but I can see it. However there is no "flicker" what so ever on the LCD screen.
Is there any test I can do to be sure that it is the LCD-cable? Where can I buy a new pair of cable (Living in Germany)? What is the name of the part?
What other part can it be? How can I test it?
Best Regards,
René 
RE: Printer is not starting after assembly, LCD suspected
Do a continuity check. Ohm between each wire in the cable, 1 to 1 ... 2 to 2 ... etc. All should measure near 0 ohms. The wire that is highlighted looks functional - not cut. It's #10 in the assembly as you test.
I'd contact Prusa support via CHAT and have them help diagnose the issue. Log into the store, CHAT is in the lower right corner.
ps: the flicker test is with power off. When on, you shouldn't be moving things around.
RE: Printer is not starting after assembly, LCD suspected
I had a dead LCD screen on mine ( probably killed by static electric shock we think), but I was able to operate the printer using Pronterface. I was able to keep printing until the replacement screen arrived.
RE: Printer is not starting after assembly, LCD suspected
Hi,
thanks a lot for the idea to contact the support. Haven't thought on that one. Just answering for others that may have the same issue.
The first think that we tried were the Pronterface as already suggested here. The connection from 3 different computers were not possible to the board. The error in the tool was always "Command not found".
Therefore we tried to flash the firmware over the PrusaSlicer tool which was also not successful. The tool could not establish a connection to the printer / board. Again tried with different computers and USB-slots to cut out this as an error. BUT the printer was correctly recognized by the prusaSlicer tool in the firmware flash screen where you need to pick the interface what you want to flash. This was particularly confusing as the flashing itself was not possible.
As the flashing was not successful, we looked at different parts e.g. the fuses from the mainboard but nothing looked wrong. We did everything as suggested here.
The support were asking the developers for other ideas but they suspected that the mainboard itself were defect. This whole testing took us several days in several chats and a long mail history. I was upset and started my own research where I came along this post which actually solved my issue: http://forum.seemecnc.com/viewtopic.php?t=1141
The board itself has a reset-button which needs to be pressed BEFORE the printer is powered on. So the button has to be hold WHILE activating the power. This solved my problem and the printer and the LCD started as it should have after the assembly. The reset button is placed on top of the board and is press-able through the enclosure.
Furthermore, flashing of the firmware also possible now.
Best Regards,
René