Sony KP-57WS500 Green Screen, lines, then shuts off

I picked this tv up today for free from a neighbor who says he had it repaired once, because it was doing the same thing that it is doing now. He said that the repair tech replaced some tubes, and that it cost him $500 parts and labor. I don't know if he knows what he is talking about, and would like some help to see if this is something that I can do myself. When I power the tv on the screen is all green, kinda fuzy, but then as the screen turns on more, I can see lines curving downwards from side to side, and then the fuziness goes away, the lines stay there, it stays green, but then after a few seconds, the whole tv turns off, and won't turn on for a few minutes, and does that whole process again. I am pretty handy with working on things, but have little knowledge when it comes to electronics and the terms that everyone is using in the forums. If someone could direct me as to what parts I need to check or replace, and the repair process in Laemans terms, that would be great.