AC adapter not recognized when the system is running, BIOS update fails

[HouseGeist]

I´m trying to fix an old laptop for a friend.It´s a HP Pavilion dv4t-1600 CTO.

I replaced some broken electronic parts but now I´m stucked in updating the BIOS. So now some facts to descripe my problem.

The main problem is: laptop won´t charge the battery while the OS or BIOS setup is running. The ac adpater is not recognized as plugged in. But when the system is shut down the battery is charging. So the ac adapter and battery are working.

The internet told me that this is an BIOS problem and a BIOS update shold fix this problem. Now the fun starts: because the BIOS update exe is checking if the ac adpater is plugged in, it won´t install (kind of funny because this update is suppossed to solve this problem but won´t install as long as the problem exists).

I followed some advice from the glorious internet, unpacked the exe file, edited an ini file and I could run the exe file to start the update process. But then I receive the error message that no ROM file could be found.

And this is where I´m stucked.

The installed BIOS version is F.65. The BIOS version I try to install is F.67 Rev. A.

I could really need some smart advice. Thanks for helping me.

[CherylG · Accepted solution]

The problem may actually be the aging power adapter is no longer producing enough power to run the laptop and charge battery at the same time. 

Does it run with battery removed and only using power adapter? If so you might be able to get the bIOS updated that way-not sure. However, I'm not confident the BIOS will solve this- the power adapter may require replacing.

[HouseGeist]

It took me some time to get a different ac adapter and also check the one I used with a different Laptop. But it really solved the problem. The ac adapter is too old or broken. Thank you for your advice!