I changed my lamp a few months ago, but now the tv makes a loud humming noise when you turn it on. The picture is still good, but it continuously makes the noise.

Vacume out where the fan is in the back of the tv. That should release alot of the built up dust. I try to do that to my tv atleast once a month. Hope this helps.

you have a bad colour wheel

I have the exact TV and had the exact same problems. It is the light engine with color wheel that needs to be replaced, and they are VERY hard to come by for this model. Our repairman has had our TV for 5 months and still cannot locate a vendor that carries the part. He said according to Toshiba, the part has been discontinued. If you happen to find one, please post. I'll do the same.

Actually that humming sound was not the lamp, the humming sounds come from color wheels when they're going out, and since the color wheel is part of the light engine system and it's not working, that's why you don't have an image, you'll probably ask your self why, since it's not the lamp.. the thing is that the light engine system is componed by lamp, ballast, color wheel and dmd board, so when one of these doesn't work, there will be no image reflected, because they work together

That sounds most like the color wheel,
to change that you need to have some skill in electronics, I would recommend to take it to a shop

Sounds like u need a color wheel

Your color wheel needs to be changed. Mine just did the same thing. I changed mine, and the buzzing sound went away, however now my picture washes out with light or yellow colors. The darks look green and purple also.

Hi, your color wheel needs to be replaced, the bearings fail causing the grinding noise, the new ones use "air bearings" so they are supposed to last much longer, video-tek

Assuming the noise is a high-pitched whine, then yes, it is the color wheel.  If the color wheel goes out, the TV will turn on for a while, then turn off when it can't establish color wheel sync.  The color wheel has to be in sync with the mirrors on the DLP, so if sync can't be established, the TV turns off.
You can order a new color wheel from Sears or partstore.com (among other places) and replace it yourself, if you are so inclined.

The color wheel is the most common problem in DLPs that cause noise. To determine the cause: Turn the set off. If the noise goes away after about five seconds, then, the problem is the color wheel. If the noise goes away one to two minutes after shut off, then, the problem is a fan. You can find an Authorized Servicer in your area that can tell you the price of repair, by clicking on the Samsung link: http://www.samsung.com/Support/ServiceLocations/index.htm