8
The Servo Quad Amplifier Protection Circuitry
As noted in the “Guided Tour” section of this manual, the Servo Amplifier's front
panel Protection lights indicate the activity of the relay speaker connection
circuitry. When the Protection lights are 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 lights 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 Quad
Amplifier begins delivering signal to connected speakers. It is normal for the
Protection light to fade gradually after the amplifier is powered off.
• Overheating: A temperature sensing device in the Servo Quad Amplifier will
cause the relay speaker connection circuitry to be deactivated (and the
Protection light to go on) whenever the operating temperature of the unit rises
above a safe level. To guard against this problem, make sure the Servo Quad
Amplifier 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 Quad Amplifier 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 Quad Amplifier short one another.
• Output impedance drops below 2 ohms: This can occur if the Servo Quad
Amplifier is connected to inappropriate speaker systems (see the “Setting Up
and Using the Servo Quad Amplifier” section on page 5 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 either or both of the Protection lights go on (other than
during the approximately five seconds following initial power-up), there is reason
to be concerned. If this occurs, turn the Servo Quad Amplifier off immediately
and carefully check all wiring and external devices in order to locate and correct
the condition that caused the light to go on in the first place.
WARNING: If a Protection light fails to go out (and you fail to hear the
accompanying audible click) approximately five seconds after power-up,
turn the Servo Quad Amplifier off immediately and check all external
devices and wiring for possible shorts or other defects.
CH3/4
PROTECTION
