Since the 8P5431 is a rear projection unit, the first place I'd start with this is looking at the lamp. If the lamp is on it's way out, or if there's a fault with the lamp unit, it would manifest itself in this way (you've got picture going on and off, but got fine sound, and there's clearly power to the unit).
I'm not an expert on rear projection, so unless you are, it might be time to get a TV repair shop involved. I can't imagine it's going to be hugely expensive... That said, a quick search on DLP Lamp Source (nb: This is a random site that I've found on Google and I in no way endorse it!) lamps are starting at around $170 (I'm not making an assumption that you are an American, it was just the first result for a guide price).
Don't forget that rear projection is an older technology now, and if it's starting to look costly to repair, you might be better off investing in a flat screen of some description and making the step up to HD :) it's totally worth it.
Hope this helps you out.
I'm not an expert on rear projection, so unless you are, it might be time to get a TV repair shop involved. I can't imagine it's going to be hugely expensive... That said, a quick search on DLP Lamp Source (nb: This is a random site that I've found on Google and I in no way endorse it!) lamps are starting at around $170 (I'm not making an assumption that you are an American, it was just the first result for a guide price).
Don't forget that rear projection is an older technology now, and if it's starting to look costly to repair, you might be better off investing in a flat screen of some description and making the step up to HD :) it's totally worth it.
Hope this helps you out.
