Windows 7 - Ugh laptop, motherboard issue?

its an hp, thats my first problem
but my main problem is, the laptop wont run off AC
theres a little light by the ac adaptor port that lights up when the charger is plugged in, win 7 also says "plugged in" and i believe even says charging when its plugged in (so it IS detecting the cord being plugged in) but it will not run off of the ac adaptor. i even tried starting the computer with JUST the AC adaptor (rather than pullin the battery while the machine is running)

when i plug the machine in i also noticed the lightening bolt (battery?) light just blinks..
the light does howeever stay solid once the machine is turned on.
the machine will not charge period (machine on or off)
will not run off the ac adaptor
will only detect that the ac adaptor is plugged in, and thats all. any suggestions anyone? i cant think of anything but needing a new motherboard. thank u very much.

There is also the distinct possibility that the AC adapter has failed. They do burn out.

That would be the first thing I would test. Can you borrow an identical AC adapter from someone? (Needs to be the same Volts, Amps, and Watts as the original and have the same connector plug type)

Your local walmart should carry HP AC adapters for laptops, everyone I've been in has them and for around $50.

ive already tried a new ac adaptor, the ac adaptor keeps the other laptop on fine
ive tried a dif battery too

I had the same problem with an HP laptop (HP 6170) & tried the same things you did. It turned out to be an issue with the power management module on the motherboard. Since it was about 4 or 5 years old, I bought a new laptop, as replacing the motherboard was not cost effective.

Sorry I don't have a more encouraging solution.

nah thats fine i just wanna know its the motherboard before i toss it ya know?