Laptop shutdown when ac adaptor is plugged in

I have toshiba satelite a200/j01
it's been a year and i started to have this problem:
my laptop frequently shutdown while i'm using it.

then later i realize that if the ac adaptor isn't plugged, it works just fine.

but whenever i plug the ac adaptor to my laptop when it's on, the laptop suddenly shutdown without any warning. the only time i can recharge the battery is when the laptop is off.

it's just frustrating that now i can only use my laptop for around 1and half hour then shut it down and recharge it again.

my question is, do you think it's something wrong with the adaptor or the battery or is it something else?

please help me, this problem has buggin me for a while now.
thank you.

 

That is weird. If I were to hazard a guess, i would say it's the DC/DC board. The DCDC board is responsible for switching your laptop from battery to ac power and back again. Sometimes it is integrated on the motherboard, sometimes not.

It sounds like your's is stuck on "battery" so you are always drawing power from it--with this stuck this way, you draw power faster from the battery than the system will charge the battery, hence the shutdown

Since about 95 percent of laptops have the dcdc board/function integrated on the motherboard, you probably need to replace the motherboard

 

thanks for the answer gerryf19.

just to make sure if that's really the case, i'll tell you more of the symptoms:

before my laptop only shutdown in rare occasion, but it keep getting worse each day.

before it only shutdown after hibernation (i thought it was vista bug) then it fail on startup several times and then keeps shuting down while i'm using it, it keeps getting worse each day, now it might only last 2-3minute with both battery and adaptor (that also after several times rebooting).

i tried testing my power adaptor using multimeter and the output is 24volt when it's suppose to be 19v (in the label), i dont know if it's normal or not because i tested my friend's and it also said around 23v when it's suppose to be 19v as well.

and testing without battery (just the power adaptor plugged in) my laptop is able to run for around 3-5 minutes before it's shutdown itself. no problem on startup.

only if i run it with battery without the adaptor, laptops works perfectly fine, no problem at startup and after hibernation as well.

i wish it's really not the motherboard (cross fingers) because i think it will cost a lot =(

but anyway thanks again for the information =)

note:
os: windows vista sp1
before this happened i rarely shutdown my laptop (only hibernate) and always put in both battery and adaptor.

 

I was pretty certain I was right, until I read this:

That kind of throws my whole theory out the window. You shouldn't run at all without the battery under my scenario.

Now we are back to heat, though why it runs so hot some of the time and not others is a mystery.

I'd be pulling it apart, cleaning the dust bunnies and see if there is a heatsink crack or faulty fan

 

thanks for the confirmation

and yes i notice my laptop becoming quite hot when it's on power adaptor, however if it's a heat problem i dont understand why it also failed on cold startup (after i shutdown and leave it overnight and also after hibernation).

so btw in this case, it's totally nothing to do with bad adaptor or battery is it?

i think i'll try opening the case and cleaning out the dust, i'lll post the result here after that.

thanks

update:
i finally decided to bring my laptop to repair center cos i'm not confident pulling my laptop apart myself. It apparently the cooling system (so you're right about the overheating) and battery that need to be replaced. it's not under warranty so cost me around $250 to get it fixed.