Check that the power cable is securely plugged into the unit and ensure the breaker has not tripped if you are not receiving any power. If the breaker has tripped, reset it to restore power. Check that the power cables are not damaged.
Turn the "AF GAIN" knob clockwise if there is no audio coming from the speakers. Keep turning it until the sound is audible. Alternatively, the lack of sound may be due to the appropriate cables not being plugged in; make sure the external speaker cable is plugged into the speaker jack on the external speaker.
Turn the "RF GAIN" knob clockwise fully if the sensitivity is low and only exceedingly strong signals are audible. This problem may also be due to a damaged antenna line; you should visually inspect it.
Turn the "MIC GAIN" setting clockwise until it reaches the center position (the 12 o'clock position, as you look at the dial) to remedy low power output or no power.
Ensure the area around the unit has as much ventilation as possible if the back panel begins to heat up. This can become as hot as 40 degrees Celsius (104 degrees Fahrenheit), so it is important to keep it as cool as possible.