Half screen lighter than other half

There is one power supply but it is divided into several circuits. You have line volts coming in AC then there are regulators to keep the various supply voltages steady for each circuit area. each manufacturer takes time to disign power supplys for their sets but no matter who makes them the theory is the same for all. I hope to help you but it very hard to try and explain something especially when I cannot be at the device haveing trouble. One word of caution for you be careful handleing your plasma GLASS is heavy have a friend help you move it some sets you can remove the back while it is still sitting on its base (stand) some have to be placed face town on a study bench or table use a blanket to protect the face of the set. Just be careful and try not to get so discouraged even as long as I have been in electronics repair I still get a little tight. Most repairs for your plasma will involve replacing entire circuit boards. Some manufacturers parts are realativly (cheap) in price some will make you cry. There is one power supply but it is divided into several circuits. You have line volts coming in AC then there are regulators to keep the various supply voltages steady for each circuit area. each manufacturer takes time to disign power supplys for their sets but no matter who makes them the theory is the same for all. I hope to help you but it very hard to try and explain something especially when I cannot be at the device haveing trouble. One word of caution for you be careful handleing your plasma GLASS is heavy have a friend help you move it some sets you can remove the back while it is still sitting on its base (stand) some have to be placed face town on a study bench or table use a blanket to protect the face of the set. Just be careful and try not to get so discouraged even as long as I have been in electronics repair I still get a little tight. Most repairs for your plasma will involve replacing entire circuit boards. Some manufacturers parts are realativly (cheap) in price some will make you cry.