I just finished assembly of Anet A8 (Prusa i3 clone). X any Y work fine, both Z motors move down just fine, when homed.
On Z-stop trigger, right Z moves up, left Z continues to try to move down. When up command is given in Pronterface or RepetierHost, right Z moves up, left Z moves down. Switching cable plugs moves the problem: the down only moves are always on Z-Motor1 output.
I have flashed the firmware with original Anet Omni firmware and problem persists. How else can I test if the problem is hardware- or firmware- related?
I am reluctant to change to different firmware entirely, as I have not yet found out what the problem is.