Sanyo DP39E23 turns on for 15 minutes then the screen goes black
"Allen Hauser could be a power board issue or a backlight issue. When the screen turns dark, in a darkened room, shine a flashlight beam at an angle against the screen. If you can make out shapes/silhouettes you know it is the backlight (possibly backlight LED strips). If you do not then you will have to remove the back cover and check the power board and main board connectors to see if the voltages are as required. Post some pictures of your boards with the question so we can see what you see.
Adding images to an existing question"