Chosen Solution
Hi, I got a Magnavox 40in LCD TV (40MF401B/F7) with a display problem. When I press the power button, the tv turns on and lights up and the words “DIGITAL TELEVISION” are displayed, then the screen goes dark. Picture is visible when a light is shined into the screen and sound plays fine. Problem persists on HDMI and Component inputs with different devices. Vertical black lines also sometimes appear within the picture and did so before the screen stopped working. Checked tv settings and all appears normal but haven’t yet found how to do a factory reset. Any suggestions for some diagnostic or repair steps would be greatly appreciated. Thank you!
@sylp “Picture is visible when a light is shined into the screen “ means your main board is displaying the video but you have no backlight. Check the power board for any obvious damaged components. Measure the voltage output to the LED backlight from the power board to the LED’s let us know what voltage you get (connector CN1914 Pin 1-5 should give you 24V). It is possible that this is a power board issue or a failed backlight array. Post some pictures of all of your boards with your question so that we can see what you see. Use this guide Adding images to an existing question for that. It will allow us to see what you see.
I dont know if it will be the same on a lcd but i would check for an “Inverter” or “Backlit” loose connections
