Your lamp is very likely getting old. This type of TV will require new lamps depending on its use, but generally they will last 2-3 years average. They can be purchased online and are very easy to install. This set is made to allow the owner to easily change the bulb.
The only moving parts inside are the fan and the color wheel. The fan continues to run for a bit after you turn off the TV, so if you are hearing the sound after your power down the set then I would suspect the fan. If the sound goes away as soon as the picture goes out, then most likely you will need a new color wheel soon. On my set, the sound kept getting louder until one day I turned it on and the picture went dark, and the sound stopped. I had to replace the color wheel. If you warranty is out you can do it yourself. There are step-by-step videos on youtube for replacing a color wheel.
Just replaced the lamp (HL-R4266W) and ...............
Just replaced the lamp in this unit and it worked beautifully for 3 weeks. Now a low pitch "humming" and/or "whistling" sound, almost like a loose fan, is coming from the rear of the TV. The picture has also become "watered down". The lamp light on front is also on again. Any thoughts?
Sounds like your Color Wheel is cracked/chipped. It is one of two moving parts a DLP television, the other being the fan. I had this same thing happen to my set and it got louder and louder before it finally exploded inside the set. Nothing else got damaged but there was a lot of particles inside that had to be carefully removed. A new color wheel cost me $100 and I found a step by step replacement video on YouTube with just a quick search.
last evening while watching the tele, the picture went out of focus and there was a loud buzzing/humming sound. I turn it off and tried to restart but it wouldnt. The power button is now flashing with the lamp, timer, and standby mode illuminated.
the fan in my HL-R4226W turns on full blast to the point where you cant hear the TV. The Picture is very dim and almost black and white. I'm not sure what to do to fix this problem and i do not want to have to take it to a store if it is avoidable, especially since the store i bought it from is now closed. I bought the TV in October in 2005 so i didnt expect it to do this so soon. Please help me with this problem thanks, Chase