Posting to software, but this could also be an electrical issue.
After numerous issues with my initial build, including 5 bad step sticks, and a power supply that just quit mid-print, I've had a very good weekend printing, finally. FT support has been very helpful through the process, and to date have sent me a new LCD screen (original cracked in shipment), a new Marlin board w/step sticks, and a new power supply.
Before the new logic board showed up, I was able to borrow a set of step sticks from a friend, and was actually able to get my printer working and printing. It was amazing. Right up until the power supply gave up while printing the first layer of a print. I changed the fuse, and no luck. FT support sent me a new PSU very promptly.
So, once the new PSU showed up, I replaced the defective PSU and the original logic board with fresh new components. Everything powered up nicely, and I attempted my first print, from the SD card. First layer started beautifully, but it skipped several lines. Second layer got stranger, as the print head just randomly moved to the X0 position, the moved back and started printing again, a few lines away from where it had been. I was printing the reference cube that had printed successfully before, so I was a little confused.
I found success by going back to the Repetier Host application, and printing directly from that. In fact, I've probably made over a dozen successful prints this weekend using that mechanism. Tonight, I decided to investigate the SD card issue again more thoroughly, and found that there is indeed something wrong.
If I print the 20mm hollow cube from Repetier host, it prints perfectly. If I try it from the SD card (same slicer output), it fails in some (different) random way each time. I'm wondering if there might be some sort of issue with the LCD/SD Card Reader? Maybe when the original PSU failed, it sent current in such a way that the display failed as well?
One thing I've noticed since the PSU failure is that when the Arduino board is powered over the USB only, no 24v supply, the display flickers a little. When I had things working the first time, even with the original cracked display, I don't recall seeing that flickering. Since installing the new logic board, and the new PSU, the flickering is still happening.
First fail video link. A little hard to see, but if you look closely, you can see it blot out a bunch of filament at the back of the first layer at about 50 seconds in. More layer issues with 2nd and 3rd layers with areas just skipped.
Attempted another print from the exact same file and card, and got the more usual result. Random trips off to the sides of the print surface. First one at 40s, then again at 1:08 and 1:47
Final video is of the print from Repetier Host over a USB connection. No issues whatsoever.
So, any thoughts? Suggestions?