Audio Systems: Car Stero sounds, oldsmobile alero, 1999 oldsmobile alero

Question
Hi,
Could you tell me if you know how to fix my problem. i have a 1999 oldsmobile alero. the AM Mode on my stereo makes a whining noise with my engine rpms (stock factory stereo, no mods). high pitch. i was just wondering if you have encountered that problem. it just started a few days ago and i have never had problems with it. also it may be unrelated(electrical maybe) but my anti-lock brake light went on a couple days in a row and hasnt since. let me know please if you have time. thank you Rich

Answer
Rich,
Your stereo may be picking noise from the alternator. Alternators have built in noise filters that filter out the ripple from the output of the alternator. An alternator generates AC voltage that is rectified to a DC voltage by the diodes inside the alternator. The ripple is the component that is left over by this process. Due to the high temps under the hood of most vehicles the internal filters will sometimes fail without warning. Your only recourse is to replace the alternator or install a high current external noise filter on the output of the alternator. The filter should have a current rating of at least the rated amp output of your alternator.

TOM,
T&D ELECTRONICS
tdeser@zoominternet.net