compaq presario r3000 laptop mainboard power problem

Hello,

My compaq developed a power related condition. It works from battery but when trying to charge it gives me power light on for about 6 sec then blinks and so on. The same time the power light blinks you can hear a buzz sound coming from internal dc converter area on the mother board and the battery charging voltage on charging pins drops about 1 volt down to slowly increase again(not sure if its a normal bahaviour or it is related to the issue).

When i am trying to turn it on without battery it turns on for a split of a second and then turns off (I gues something is cutting off the power)

The bottom line is it works from battery, it can charge the battery but it doesn't want to turn on from ac and under windows it doesn't recognize when the ac is plugged in when working from battery.

I was trying to pinpoint the failing component on the main board dc converter circuit but i don't know what kind of abnormalities i should be looking for.

Can someone help?

sounds like a related issue discussed in the thread "Presario 2100 broken power connector".

are you sure the AC adapter is charging the battery? when the laptop is off, sometimes the light turns yellow to indicate a charging and you may hear the electronic buzz for a brief few seconds, but it will cut off afterwards if the connector isn't making a good connection. there's some places that do almost nothing but these types of laptop repairs. I guess you can leave it to charge until the light turns green, take out the battery and check on the little LED status lights. (most hp/compaq batteries have these I think).