Thanks Vic, I'm not convinced the circuit diagram is correct/complete as it's showing a transistor controlled relay on all the other functions but no coil for the power switch relay (I doubt all the panel systems are powered through a transistor). My guess is the detail on part number 18 "control unit/switch module" as it will have current limiting resistors for the other switch circuits and I assume a latching momentary switch circuit (press on/press off) for the power supply.
I'll take it out tomorrow and reverse engineer it.
