Magnavox troubleshooting this set turns itself off after approximately 30 minuets of use. do you have a remedy for this?

This problem is typically caused by one or both of the cooling fans in the set going bad. The fans are located under the bulb housing and on the side of the set at the left vent hole. You can check the status of the fans by using your remote to access the TV's set up menu as follows:

Select "source" on the remote
hit the "up" arrow twice
hit the "down" arrow twice
hit the left arrow
hit the right arrow
hit the left arrow
hit the right arrow

At the setup menu select the item that says something like "thermal status" or "thermal properties" and look at the speed of the two fans. Properly working fans will have a speed of 1500 RPM or more - they should be close to 2000 RPM. If the fan speeds are less than 1500 RPM this will cause and overheating problem and they should be replaced.