Power issue, clicking noise, turns off (by 2 users)

The clicking is the power on relay closing and opening. This happens because the TV has several built in safety systems that will detect and over voltage and over current load situation.The power supply starts up for an instant, senses and overload of either or both kinds and then the safety switches trigger a cutoff. When this happens the power supply will not start up again because another circuit called a latch keeps it disabled. By unplugging the AC cord and trying to start it again releases the latch until the failure triggers it again.
On these TVs the power supply is rarely the cause of the shutdown. Something further down inside the TV has failed. Replacing just the power supply will not fix the problem. The most common reason there would be an overload would be in the high voltage circuit that lights up the 3 CRTs, next would be the coils around the CRTs that bend the beams to make the picture. This is normal circuit aging and wearing out. Unless you are very skilled with trouble shooting TVs I would recommend having a service center look at it. An authorized JVC shop would be your best choice because they will have access to the manuals and bulletins and have probably had other similar JVC units thru their shops.