I am very grateful to Ken Hanscom for posting this article about how to adjust the voltage on the color tubes in my rear projection TV (Sony 57WS500 that we bought in 2002). A few months ago I started noticing that when the screen was very dark or black (like when there was no input) I could see a series of blue arcing lines across the screen. Then a month or so ago the entire screen would have a very noticeable blue cast when it first powered up. It got to the point a few days ago where the entire screen would go to about 95% blue for the first five minutes every time we powered it up.
I spent about 10 minutes following this guide to pop off the front grille and make a very minute adjustment to the potentiometer for the voltage to the blue gun and now my blacks are nice and crisp again. This saved us from having to watch blue TV all the time or buy a brand new set. Thanks Ken!