SAMSON SERVO 120
Manual de Usuario

The Servo 120 Protection Circuitry
As noted in the �Guided Tour� section of this manual, the Servo 120's front panel Protection LED indicates the activity of the relay speaker connection circuitry. When the Protection LED is lit, this circuitry is inactive, and all connected speakers are muted (provided with 0 volts DC), thus protecting them and preventing any audible �thump� from occurring. The following conditions will cause the Protection LED to go on: � Initial power-up: For approximately five seconds after initial power-up, the relay speaker connection circuitry is deactivated and the speaker output is muted. If everything is operating normally, you will hear an audible click at the conclusion of this brief period, as the circuitry is activated and the Servo 120 begins delivering signal to connected speakers (at which point the Speaker LED will light if the Speaker on/off switch is in its �in� position). It is normal for the Protection LED to fade gradually after the amplifier is powered off.

PROTECTION

SPEAKER

WARNING: If the Protection LED fails to go out (and you fail to hear the accompanying audible click) approximately five seconds after power-up, turn the Servo 120 off immediately and check all external devices and wiring for possible shorts or other defects.

� Overheating: A temperature sensing device in the Servo 120 will cause the relay speaker connection circuitry to be deactivated (and the Protection LED to go on) whenever the operating temperature of the unit rises above a safe level. To guard against this problem, make sure the Servo 120 receives adequate ventilation on all sides (see page 5 for more information); in extreme environmental conditions, you may also want to consider the use of cooling fans. � Severe overcurrent conditions: This occurs whenever the signal being input to the Servo 120 rises to a level above 20% THD (Total Harmonic Distortion). � Shorted speaker cables: This will occur if, due to faulty wiring, the hot and ground signals being output by the Servo 120 short one another. � Output impedance drops below 2 ohms: This can occur if the Servo 120 is connected to inappropriate speaker systems (see the �Setting Up and Using the Servo 120� section in this manual for more information). � DC voltage detected at speaker output: The most likely cause of this is an internal failure.

In general, any time the Protection LED lights up (other than during the approximately five seconds following initial power-up), there is reason to be concerned. If this occurs, turn the Servo 120 off immediately and carefully check all wiring and external devices in order to locate and correct the condition that caused the LED to light up in the first place.

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