I have a philips big screen projection tv modul#55p8341 that turns off after being on for a while. great picture and sound

The most likely cause is shorted convergence chips and possibly a few pico fuses.

These sets need to have all three colors - RED - BLUE - GREEN - lined up correctly on the screen in order for the picture to look normal. This is called convergence.

When its out of alignment the video will look 3-D, wavy, distorted, etc. Most of the time you just need to adjust your convergence in the menu. If you cannot adjust it in the menu - then your convergence is broken and needs to be repaired. Convergence problems are very common on all Projection TV sets including Sony,Samsung,JVC,Philip Magnavox,Panasonic,Akai,Pioneer Hitachi,Mitsubishi,Zenith and others.
You can get a convergenece repair kit with instructions from the links below.

Here are some of the most common problems with these sets...

Problem #1) Convergence

Yours may have one or more of the following symptoms...

*Screen Looks 3-D
*Colors wont align
*Screen may look distorted or warped
*No Audio/Video - TV Shuts down - May also make a constant chirping sound

Problem #2
Another common problem is dull or washed out video.

Your set may have one or more of the following symptoms....

*Dull looking picture
*White looking picture
*Halos around objects
*Red/Orange looking picture

You can see some more examples and find a fix herehttp://www.fixya.com/support/r2861467-solution_video_looking_whiteish_dull

I am having the same issue! Ugh!

I HAVE A PHILIPS M#55P8341A THERE IS DOUBLE PICTURE ON THE SCREEN IF YOU HAVE ONE PERSON THERE YOU SEE TWO OF THEM ONE IS RED THE OTHER IS GREEN?

my projection tv color is red I have tried ajusting the color but nothing the pic is still to red

Same problem... I pulled out the second electronic board going from right to left and see a burned diode at position 3307. I wanted to know if anyone has a schematic of this TV and could tell me the numeric value of the part in position 3307. It would be appreciated it you could let me know.Thanks...

5 volt protection is causing the set to go into protective shutdown. Check for shorted diode 6306. Part#934038020127
or shorted capacitor 2318. or faulty voltage regulator

sounds like your red tube is getting a short I can post you a web sight and they have used red picture tubes
http://servicemanuals.vstore.ca/

Let me get this straight, you don't have a picture as long as the unit is on, but when you go to turn off a picture flashes? Questions, first how is the picture when it flashes briefly? Is it normal or with colors misaligned? How is the sound? Could be a loose connection or bad capacitor in the video circuit.

Unplug it for a while then try it again.

This is a common problem with older Philip Magnavox projection sets. Over time one of the IC chips on the main power board begins to fail. You can find replacment chips and repair instructions on www.magnavoxhelp.com.