Laptop Power Supply?

[leopardfist]

I have an old Gateway PA1 that I inherited. I put Linux on it and it runs very nicely except for one problem. The screen brightness changes from light to dark and back again. The fan seems to turn off (laptop gets quiet) when the screen is dark. When the screen brightens again, the fan noise also resumes. This makes me think there is a power issue with the board.

How can I diagnose is this is the issue and is there a repair short of replacing the motherboard entirely?

Thanks.

 

[jaguarskx]

Did this problem exist prior to installing Linux? It could software related.

 

[leopardfist]

I don't know because it didn't have an OS on it previously. I have another PA2 which runs the same Linux distro flawlessly, so I think we can rule out software as the cause.