Yamaha RX v3000...starts clicking rapidly when I plug in into the wall socket...without even pressing the power button. However, two large resistors on the F-Amp board get extremely hot rather quickly. How does energy get to the F-Amp board when the receiver isn't even powered on??? Guess it's an obvious short somewhere in the circuit...but I've not seen this happen before....when the unit is powered off. Don't even know where top begin to look...
Sounds like an issue with the standby PCB or even the control microprocessor. In cases like these, I'd suspect someone else has been in there before you and screwed something up.