I have a Samsung hl-r6768w 67" DLP. Has worked fine for over 3 years now. When I turned it on today, I heard a small popping sound followed by a buzzing sound that does not stop. The TV still works, but only shows B/W on the screen. I took off the back cover and the buuzzing is coming from behind the back cooling fan. Any ideas?

First thing I would try is to remove set and a box or receiver if used from power for a while and then plug all back up--should reboot all units that way--cannot hurt and may very well help. Not just the set but any unit between signal source and set.

It might also be a good idea to see if when the screen is black if the lamp can be seen--is it on or not?

Check the lamp if its more than two years old, otherwise check the color wheel.

Go to this Website and type in your Model number they will List Parts/Prices for your TV, They also have CD Service Manual you can order!
Encompass Parts Distrubtion 1-800-638-3328

When you know Part number you can go to Ebay ,Look under Electronics ,Thats where I find alot of Parts Cheaper then what companys want for them.

You might be Looking at replacing Light Engine or the Dmd Moduel Order the CD it will help you out alot.If one side of screen starts turning Green and wrong flesh tones it is the Light Engine

1/2 meaning. Left or right side?
This could be an issue with the DLP Chip.
Would have to go in for servicing.
Blessings,
A/V Media Tech Guy

Check your color wheel. There is a DIY guide for replacing the color wheel. Mine did the same thing yours is and my color wheel was all busted up. Unfortunately after replacing the color wheel my set continues to do the same thing, but this could mean I need to replace the ballast as well.

sounds like you need a new lamp

Look at the fan and verify its comming from the fan and not the power supply unit, you can clean the fan or replace it, but yes the fan would be likly the problem. Make sure you double check the power supply unit and clean if its needed,

Rulds2008

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/edwy_1a56970cf1ea4620

it was bad bulb

disconnect the power and hold in the power button for 30 seconds to reset it.

My 3 yr old Samsung DLP has the same buzzing noise, had a tech out today and he said "color wheel". Thank goodness I purchased that expensive warranty, This is my 4th repair in 3 years.