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The heart of an audio system is the receiver, which serves as the master control for all audio signal sources. It modifies and controls the signal with volume, tone, and surround sound processing (on more advances units) and amplifies the signal to power speakers. It also usually contains an FM and AM tuner for radio signals.

Today's manufacturing techniques combine many electrical circuits into one plastic logic chip the size of a postage stamp. This means that tuning, for example, is basically computer controlled and must be serviced by a qualified technician.

However, even a receiver that works poorly can be restored to life with a thorough cleaning. Most receiver problems are due to oxidation of electrical contacts and jacks. Use a pencil eraser to clean cable pins on a regular basis. Use electrical contact cleaner to clean input jacks and speaker terminals.

Faulty switches can be located by jiggling each one and listening to hear if the sound goes on and off. If so spray the switch with contact cleaner. A dead receiver may be due simple to a blown fuse. Remove the housing by unscrewing screws on the bottom or side and slide the housing off. Locate the fuse and replace, if necessary.

Power Supply

Receivers generally have a primary power supply that powers most of the electronic components. Look for a fuse and component group on the main circuit board that is connected to the transformer with heavy gauge wire.
There might also be a secondary power supply where the power cord enters the housing. If the receiver does not power up, verify that the outlet and cord work properly. If so, the transformer or power supply (rectifier circuit) might be at fault.

If a fuse is blown, isolate the secondary supply by disconnecting it from the primary transformer, then replace the fuse. If the fuse blows again, replace the secondary supply board. If the fuse does not blow, test the transformer.

Unplug the primary power supply from the transformer; if the fuse no longer blows, the problem is with the primary power supply. This and other more serious problems will need to be handled by a qualified technician.