hello. if yourre getting the standby light that alters when you hit the standby or channel button i would assume that the psu is ok, when i get to work i will dig the manual out, from memory the light flashes until the P.on from the main signal board is established, if this line, 3v, is not present you will get these symptoms, as an aside on the 37in of the lz55, these blast the psu, the 5v standby line retains but the switched lines disappear when the main psu fail. the markings are on the board, check the power on from the micro, do you need the circuit diagram?
tony walker