The Problem is your P.S.U (Power Supply Unit) - if you open up your t.v (without the power lead plugged in!) and follow the lead/wires behind where you would plug the kettle type flex into, they will lead to the P.S.U, on here you will find a number of black/blue plastic wrapped cylinder shaped components with an aluminium top with a cross stamped across them, these are called capacitors! Check all of these components visualy to see if the tops are rounded (they should be flat) or have any brown crusty substance leaking out around the center (remember not all faulty capacitors have this visual indication that they are faulty). Typically the capacitors in question are Marked 1000 uf 10v, and if you can see that they are faulty/leaking replace them. Not all capacitors can be seen to be faulty so replace the whole set if not (usually 5 or 6 of the same or near value as above). This will fix around 8/10 clicking Plasma/Lcd tvs.
Remeber to put the new caps in the right way around (as they originally were + to + and - to - ) or they can/will pop and maybe cause injury!!! if your not confident in doing the repair then dont even try!!!!
BLACK-U.K, September 2009