From an eHow tech article:
"The most common sign that the color wheel is beginning to go bad is a high-pitched hum that it tends to give off. This hum can be noticeable as long as six months before the wheel goes out and is caused by the bearings starting to fail within the color wheel. Eventually, the image on the screen will freeze and lose color."
Read more: Troubleshooting Problems on Samsung DLP Projection Televisions | eHow.com
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