Im using an acer aspire 6930z, the dc in has always been a weird 90degree jack that is somewhat loose however has never really fallen out or anything. now, for whatever reason my laptop backlight is flickery and is generally on "less than full" as a stable output. if i pull out the DC in the monitor goes blank (sound + generally everything else fine) and wont come back, even if i put the DC line back in until I shut it and turn it on again. Any guesses?
Having worked on and stripped a 6930 they are without doubt the worst designed laptop I have ever come across, why on earth would you combine the hinge with a dc jack. Id say a bad contact on the power jack as the wiring isnt upto much and moves due to the hinge. Maybe try a new psu just in case but my first port of call would be the jack itself.
