No picture but sound is clear

kalpana njs could be a power supply issue, a T-con board issue as well as a main board or panel issue. You will have to do some preliminary checks. Turn the TV on and make sure that you have an audio. In a darkened room, point a flashlight beam at an angle against the screen. See if you can make out silhouettes etc. If so, it’s your backlight. Time to check the main board and the power board. You do want to measure the voltages from your power board to the main board connector. If those are okay, it’s your backlight array. Since you did not tell us what you have checked or what model TV this is, we cannot provide you with an in-depth answer as on how and where to measure the voltages etc.

I would also suggest that you post a picture of all of your boards with your question. That way we can see what you see.Adding images to an existing question - iFixit Repair Guide