Whats wrong with my tv?

A guy gave me a tv. It is a 52 " Mitsubishi VS50501. He said it works but it will go off and not come back on for a while and it is progressively gettting worse. He said he thinks its a relay switch. Sounds like to me its overheating but idk if tvs have an internal cooling fan. I know nothing about tvs but I am going to try to fix it myself vs. lugging this 200lb tv to a store to fix. So my question is, has anyone ran into this problem? If so what was it and send me a link to where I can get the part.