my sony rear projection tv model # kp43t90 the picture has gon bad
Yes, we hate it when our favorite TVs lose their smoke; sometimes it's like losing a friend. (Smoke and mirrors ... I'm told once a piece of electronics lose its smoke, the magic is gone.)
If you are looking for suggestions rather than consolation, you might consider posting your message over in http://www.avsforum.com/f/63/rear-projection-units, which seems like it might be a better fit for your type of TV.