My previous post under “Vertex - Computer related problems” was that I had problems with installing the Vertex printer on my pc.
Previous post here: http://forum.velleman.eu/viewtopic.php?f=60&t=14576
After inspecting the main board I found some incorrect soldering.
I got the same issue on U3 on my mainboard, two pins and another 3 pins were not soldered correctly. I fixed it by myself (resoldered complete IC), but Velleman should be aware of this during the final inspection! There was also a cold spot on the LCD-driver board (connector to LCD) which could be easily been fixed during an inspection.