Black screen LG Plasma 50PC5D Half the screen from the bottom up is turn black with no picture , sounds good

Y-Sustan board should be suspected. If you wish to get more details, check this site. Pull up older posts there. Check the site with patience, as it has over 2300 posts now. All are related to electronic equipment repair help. Search the site by 'Timeslide' option. It will make search easy. Or, type in the brand name to your device into its search box, and press "Enter"
Fault to Plasma displays are described in detail with screen shots.

first check all of your ribbon cables. then check the lvds cable. if this dont fix then you will have to get a service manual and run the panel by itself to determin wich circuit your problem is in. any questions feel fre to contact me....

If picture only one side or only top or bottom set uses two boards to drive the screen, either one of them is bad or the actual display panel itself--it is the entire screen unit where the picture is displayed.

Maybe a tuner problem--considered hooking up whatever you use for signal to the rear av jacks? bypass the problem?

check the ratio

If you wish to get some details; visit the site linked here. Pull up older posts.
http://electronicshelponline.blogspot.com/
faults & possible causes to LCD & Plasma screen are given with illustrations. You can get an idea about the fault to an extent. Faults to all LCD & Plasma screen are similar, irrespective of its brand and screen size.

Hi Hi

LG 50PC5D-UL Plasma TV.... While playing XBox360 the screen just shrunk to the top 3" as though some one was holding a towel over the bottom portion of the screen. I have unplugged all inputs and the unit. I have let it cool down. Still it remains in this condition. I can't see the menu because it's in the portion of the screen that is "blacked out". What do I do?

With half of the screen working, and with a Plasma tv. I will look at the driver board as being bad. Take the back cover off, the driver pcb will be at the top or bottom of the set. They are only about 2 inches tall and will cover most of the lenth of the set (2 boards that run end to end). The board that is on the side of the tv that is bad is the bad board. Replace that board or have a tech replace it.

sounds like the internal screen has cracked look closeley to see if you can see any cracks if so new screen im affraid if no cracks suspect power board