Panasonic TV TX-48CX400E the screen goes off and I still have sound.

Hi guys.

I have the same problem. My Panasonic TV TX-48CX400E was working fine until last month. After that, i am watching TV, and suddenly, the screen goes off and i still have sound. I turn it off with the remote, TV goes totally off, and turn it on again, and goes in a loop. After 10-15 minutes screen goes off again and still have sound. I already total reset the TV, already change all the parameters of time, eco-mode On and Off, picture details, etc, and the only thing that helped was disconnect the TV from power socket. After disconnect tv from socket, the time that TV hold up working changed. Sometimes to less time working, other times to increase the time that still hold working. But always having this problem. Could you help me out?

Thank you very much.