You mentioned that the picture froze. Does it mean that the image just stuck or it shuts off?? If it is shutting off then its most probably a colorwheel issue or else the problem can have one of the following possible cases:
1) A colorwheel issue
2) DMD Board
1) As you mentioned that you are hearing buzzing whining sound and this is one of the symptoms of a bad colorwheel. Please look at our previous post explaining that:http://www.fixyourdlp.com/forum/viewtopic.php?f=10&t=1249&p=4172#p4172
Try to spin the colorwheel manually and check to see if it’s spinning without any problem. If it is not spinning properly, then it seems like a colorwheel problem.
Color wheel interrupts video signal to the screen and occasionally it also cuts power to the ballast. In most Samsung televisions, if there is no image projecting then the tv will shut off irrespective of sound, which is the case in your problem.
It sounds like you are quite familiar with the process of replacing the tv parts. Anyhow, here is the link to replace the colorwheel:Guide to replace Colorwheel
2) Other possible problem can be of DMD board which is like a heart of a tv. It controls other tv parts to project the image on the screen. If it is malfunctioning, the possible problem in this case might be that it is sending uncontrolled signals (or current) to colorwheel and other tv parts, which might be resulting in unusual spinning of the colorwheel. This is why you might be hearing the buzzing sounds.
With all being said I would first try to replace the colorwheel, since the likelihood of bad colorwheel is more. Hopefully it should solve your problem. And if you need one, you can buy here:Samsung HL-T5075S ColorWheelSamsung HL-T5075S Board