I have a 2004 sony 42 inch dlp the back of the screen is blue what is wrong with it

I have a 42 inch baird tv it will show the blue screen for a couple of seconds and then there's nothing just a black screen

do you have a picture of this problem

Quite typical, for an aging lamp about to go out, to get dim.

You need to replace convergence out chips in your Toshiba 57H81 tv by qualified tech because 3-D look picture in rear projection tv shows some thing wrong with convergence output chips.
Your tv model number shows it is rear projection tv that use 3 tubes to make color picture on front screen where as dlp tv use one lamp as back light source to present picture at front screen that is generated in light engine.

We have had the same problem with our 42" Samsung DLP - only two years old! We searched all over the internet for a list of ways to fix it. I found several things can help, including a switch that pops to the wrong position, cleaning the fan, etc. I put all the information together in a how-to format because it was so frustrating to go all over the internet looking for ideas on how to fix it.

http://www.ehow.com/how_4802985_fix-samsung-dlp-tv.html

Sony USA are aware of this problem and have extended all warrantees on this model till 2010!
http://esupport.sony.com/US/perl/news-item.pl?mdl=KDF50E2000&news_id=293

Both of these answers are incorrect but the first one is very close. When the lamp door warps, the picture keeps proper color but looses brightness. The second answer is just completly wrong. This set does not have a color wheel.
This set needs a new optical block and cleanning. The picture will be good as new with that. The Sony tv's are not DLP, a Texas instrument chip technology. A Digital light processor has a lamp, a color wheel and a optical chip that works together to produce the picture. A Sony has a lamp but uses a combination of mirrors and light filters to send the lamps light through 3 LCD's. The LCD's are about in inch in size for each color red, green and blue. They have millions of tiny mirrors inside to make up the picture. This method creates a better black in the video and eliminates the rainbow effect, better than a DLP but makes the LCD's work harder and heat up more because of location to the lamp. the most common problem is the blue (The closest to the lamp) starts to loose its ability to pass light so the picture gets blotches of brown/yellow because the blue is missing or reduced. The light filters collect dust and because the light is so bright when it passes though, it actuly burns the image of the dust into the filter. A home that is dusty and people smoke in will ruin one of these sets in 1,000 hours of use. A clean smoke free home will see over 4,000 but this was a problem with design and is most likely to happen again and again. Hope this help and good luck.

Its possibly the optical block. Sonny has issued a repair steatement where they are susposed to be willing to repair the issue free of charge for your model. Heres the link you should check on it as the repair is around 1000.00
http://esupport.sony.com/perl/news-item.pl?news_id=206&mdl=KDF42WE655

See this page:
http://ciscdb.sel.sony.com/perl/news-item.pl?news_id=206&mdl=KDF50WE655

Sony is covering the repairs of this problem under warranty. It is caused by a bad optical block. Go to the above page to find out about getting it repaired. Be sure to rate this solution. Thanks!

no kidding? what is the problem so prevelant in this unit? obvious design flaw.