How to change the T con board on an lg 42lm5800 3d

need to know how to change and where to get a tcon board for my lg 42lm5800 lg tv it had a white vertical bar then the screen went black but i still have sound,the guy i sent it to try and repair it said it was the t con board and lg only sells it together with the lcd an option which is more expensive than a new unit.thanks in advance