A week ago i've picked up some old stuff from my companys garbage. There were two nice Optrex DMF5010 inside (T6963C), so I decided to get them connected to my PC via Parallel Port. The backlight (circuit included) is working well from my 5 V Power supply, but I seem to have problems producing the Vee Voltage. I've rebuild this circuit:
http://www.lamepage.de/hardware/gfxlcd/ ... ly1.0a.png and it seems to work well. It is producing up to -27 V but the Poti can pull it down to -19. With a piece of software it was possible to view a clock on it, but only from a wide angle, not if i look straight onto the display. What may be the reasons for this? Is the supply to weak? On both of the displays there is a vertical line activated always - are they both damaged, or is this my fault?
TIA
Joeee