WOW, Big question. Sometimes there is a power section that rectifies the AC and splits out the various voltages. Sometimes there is a module that does all of this and more. The most important part is to find out if the unit has a transformer or not. If it does, connect a light bulb (standard lamp type) via alligator clips and make sure that the AC cord is delivering power to the power section. If there is a fuse they are usually clear glass types that you can see the fuseable link and determine if it's intact or not. If you have a multimeter set it to DC voltage and putthe neg. to case and probe around the wires that leave the power section. If you get ANY power then some of the power section is working and the problem isn't the power supply. After that it's a matter of knowing what you're doing and being able to do it. IE, Checking conductivity of parts, removing them and replacing them and soldering them correctly. Some power parts have a plastic or mica or mylar insulator covered in thermal grease and a plastic screw and nut attaching them to a good and sizable heat sink. The list of things that COULD go wrong in the hands of an inexperienced person is very long. If I valued the Receiver, I'd have someone else look at it who's knowledgeable in these matters.