I have a Dell Latitude 620 with no video display. I can attach an external monitor and I can see the display on the external monitor with vertical lines and some distortion on the display. If I reboot on safe mode I the video will be clear with horizontal lines running up and down. I replaced the LCD Inverter and that did not correct the problem.
Because of the horizontal lines on the exertal monitor I'm suspecting a problem on the video on the motherboard. How can I find out if the problem is on the LCD display or the video chip on the motherboard?