Hello I have an Acer Aspire 8930G, and about a week ago my old AC adapter sizzled and died so I bought a new replacment adapter that said it was compatible with my lappy but when it gets here it works for a whole 3 minutes and then stops charging my pc, now i know that the problem doesn't lie with my computer b/c i was using my friends ac adapter which is the exact same as my original. I've heard something about maybe needing a firmware update when reading through forums but havent been able to find anything useful.
The original adapter models specs are.
Model: ADP-90SB BB
Input: 100-240V~1.5A(1,5A) 50-60Hz
Output: 19V 4.7A(4,74A0
I'm not familiar with the Acer power connector but Dell use a three pin connector and my experience is that the computer uses the third conductor. It may be to turn off the adapter when the battery is charged or to sense the wattage of the adapter and cycle down the processor if the adapter lacks the power for full speed operation.
In other words, probably best advice is to get a refund on the replacement adapter and buy one supplied by the laptop manufacturer (whatever the cost).
The acer adapters also use the 3-pin system, at the moment I am talking to the company i ordered it from and it turns out its is probably a faulty adapter. Thank you for the help so far I'll post once i find out more.