1992 Hitachi Rear Projection

This TV still looks great. I just cleaned the three tubes and the mirror. My problem is that when i turn the TV on, sometimes it takes two hours for the picture to come in. Its not blurry but it stays black for a long while. its almost like it has to warm up like an old car. I don't want to pay some bum $300 to come to the house to fix a relay or something. I'm an electrician I can do some minor repairs myself. Please advise.