Why is my laptop screen going black when I plug in battery charger cord?
Though I am not sure what model of Vostro you have, most happen to have the video cable very close to the DC input from the power adapter. It could be that a lead from the DC input jack is in contact with the display cable and, thus, sending a wrong voltage to the display’s inverter board (or even completely grounding it out so that no power gets to the inverter) when the power adapter is installed. The only way to correct this would be to determine the cause (faulty DC input jack, bad video cable, or both) and have the appropriate parts replaced. Another option could be that there is some inappropriately-configured setting in the Windows operating system that tells the machine to turn the contrast all the way down when on building power and to set it to normal when on battery. (If I were you, I would hope for this option because this can be resolved for free while the hardware option above is quite expensive.) A workaround that you might try is just plug in the computer when you want
