Noise on laptop speaker output

[Carrot]

I've recently aquired a dell inspiron 4150 which is fine in every respect apart from the audio. When connected to my external amplifier and speakers, and to the mains power supply, the laptop emits a huge amount of noise to the speakers. It's fine if I disconnect the mains power (not very practical, particularly if I'm watching a dvd), or if I use the internal speakers (which are small, tinny and quiet). There's obviously some kind of interferance going on with the mains power, but how do I get rid of it? It's doing my head in..

 

[sypher04]

I had a similar problem with my acer laptop, although i never found a problem with the hardware.

Have you tried re-installing you sound drivers, thats how mine fixed...

p/s... did it always do this, or start shortly after you recieved it

 

[Eagleboy]

Internal audio hardware always gets some kind of interferance from areas on the mobo that draw lots of power. I'd get a PCMCIA sound card to rid yourself of the excess noise.