I'm wondering if removing D1 on a RAMPS 1.6/1.6+ remove the 12v power to the Arduino Mega 2560 board? The boards I have contain cheap AVRs so I'm going to have to build a separate power board to put 9v to the barrel connector eventually, but that's another project. For now it'll just have to be happy running off of USB (and hopefully I won't have LCD issues).
I've found several references to this forum post
RAMPS and D1 diode however, it's referencing RAMPS 1.4 and
RAMPS 1.6 indicates D1 and D2 swapped positions but it doesn't indicate if they maintained the same functions.