technika 32lcd209 screen fades to blank with two white lines ( pics now up)

[wessy67]

hi hope someone can help but my technika 32lcd209 turns on fine the picture is great for about 5 minutes then the picture fades to a blank screen with 2 verticle white lines the sound is still there you turn it off and on again and the picture is back but goes off angain a bit quicker each time