No switch if this is what you mean, the ac connects to bd via a two pin conn.
There is a three pin conn. with two wires labeled AC-L and AC-N. I looked very closely at this area and there is no "PS_ON" label
Thanks for your help, I'll wait to hear from someone.
I have searched with a magnifier for any stressed components and can not see anything out of order.
I disconnected both the X and Y boards from the PS bd and the clicking continued. The only time the clicking stopped was when I disconnected the SSB bd at the bottom.
I am going to order a SSB (3XXX-XXX-XXXX4) and replace the one in the TV. Is there any initializing or programming that I will need to do for the new bd???