How do we replace the bulb on a 73 inch tv bulb

is the lamp turning on, if not then there may be a problem with the inverter board. or the bulb is faulty, bulbs can become faulty in transit.

Replace the lamp ballast.
http://electronicshelponline.blogspot.com/

Go to menu and click on sound on this click to see if speakers are turned on if not click on if that doesnt work try the try the return to factory settings..

sounds like the psu. power supply unit. check the caps are not bulged

the capacitors on the DM need to be replaced. Very easy repair you can get the repair kit at this link which is for your model it contains the replacement capacitors and step by step insturctions.
http://servicemanuals.vstore.ca/product_info.php/pName/v21v19-mitsubishi-dm-repair-kit/cName/repair-kits

might need to change the bulb soon. Is it LED or a regular bulb?

Remote sensor is always on front of set behind a clear or tinted small lens and inside it usually is on a circuit board .

Is this a DLP or LCD projector?

we recently cracked our lenticular screen on our 73 in mitsubishi i called the manufacturer and they said they no longer make them. so i looked thru websites to see if i could find some one with a 73 in tv or bigger that they were no longer using or didnt work and i found a guy on www.ksl.com that had an 80 inch tv and we went to go pick up screen cut it to my tv size and it worked!!.