The problem will be a warm-up fault very probably in the power supply - the set is good when cold - then it starts to warm up and a component fails - turns off and gets cold - then turns on and gets warm.
Your choices are to take it to a TV doctor - get a new set - or try to fix it yourself.
If you try a home-fix a can of freezer spray might help - you squirt it on components you suspect might be the cause and observe what happens. The alternative is a hair dryer in an attempt to accelerate the fault condition.
Good Luck..., August 2016
