50" LG Pasma tv, 2005 model the screen just went black.

SOURCE: LG Plasma TV model #DU-42-PX12X

try contacting LG see if there is a backlight if there is that is most likely your problem

SOURCE: LG 50PX1D 50 in. Plasma TV

i just had the same problem. after talking to many tv repair people i finally got a knowledgeable person to help me. i ordered the part and fixed it myself.
it was very easy. i have an LG model# 50px1d. so if you had this problem i suggest you order the part yourself and fix it. i got an estimate for repair and it wouldv'e cost me at least $500 parts and labor. i paid $230 for the part. so you can see i saved a little more than half. the part you need is the " Z SUS " ASSEMBLY. you can order the part from LG website. the part # is 6871QZH044C.
let's just say after doing everything myself, i am watching TV right now.
by the way LG would not help me at all. spread the word that LG is not a good product.

SOURCE: LG 50PX4DR plasma tv

I had the same exact problem as posted above. My 50" LG plasma was out of warranty for 1 year! I called the LG executive call center, and they were very helpful. They offered to pay for the parts and labor. They recommended a few local repair shops, and they set everything up for me. The tech came out within 4 days with one part. The tech had to come out one more time the following week, since more parts were needed for the repair. The Y sustain board, along with 2 adjacent parts that are required to be replaced as a set, and the power supply had to be replaced (parts alone cost just over $900). TV is like new again; I'm very happy with how LG handled it, and made what could have been a bad experience a good one.

SOURCE: Purchased LG 50PX1D; 50 inch plasma TV from Best

that you internal projection lamp has failed

SOURCE: LG 50inch Plasma received loud sound then went black

I had the same problem with my LG 50 inch TV that I bought from Best Buy in Nov 2006. Fortunately I had the service plan. They had to replace the power supply board as 9 capacitors popped, so the TV would turn on them pop and go black and turn itself off. The TV has been a pain. I have the built in DVR and that has failed twice. I have had 3 repairs through best buy. One more time they owe me a new TV when they come out.