you likely have a power source problem.
Capacitors help to store and maintain a level supply of electricity to key components of the TV, such as its audio board or the LCD screen. When these capacitors overheat, they emit a gas which causes them to expand. This expansion causes these small, cylindrical pieces to make popping sounds.Also bad capacitors in the source can make the tv shuts off.
Once a capacitor begins to expand, it must be replaced.
if you want to have an idea of what is going on and what it would cost to repair, here you are a link of a technician service www.tvrepairjacksonvillefl.com
joel
November 2012