The Sz Series Protection Circuitry - Samson SZ240 Owner's Manual

The SZ Series Protection Circuitry

As noted in the "Guided Tour" section of this manual, the SZ Series front-panel
Protection LED indicates the activity of the relay speaker connection circuitry. When
the Protection LED is lit, this circuitry is active, and all connected speakers are muted
(provided with no signal), 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 protec-
tion circuitry is activated and the speaker outputs are muted. If everything is operat-
ing normally, you will hear an audible click at the conclusion of this brief period, as
the protection circuitry is deactivated and the SZ Series begins delivering signal to
connected speakers (at which point you'll hear the click). It is normal for the Protection
LED to fade gradually after the amplifier is powered off.
WARNING: If the Protection LED fails to go out (and you fail to hear the accom-
•
panying audible click) approximately five seconds after power-up, turn the SZ
Series off immediately and check all external devices and wiring for possible
shorts or other defects.
Overheating: A temperature sensing device in the SZ Series will cause the protection
circuitry to be activated (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 SZ Series receives adequate ventilation on all sides and that both the front
and rear panels are unobstructed.
• Severe over current conditions: This occurs whenever the signal being input to the SZ
Series 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 sig-
nals being output by the SZ Series are shorted to one another.
• Output impedance drops below 2 ohms: This can occur if the SZ Series is connected to
inappropriate speaker systems (see the "Setting Up and Using Your SZ Series" section
on page 10 in this manual for more information).
• DC voltage detected at speaker output: The most likely cause of this is an internal fail-
ure.
In general, any time the Protection LED lights up (other than during the approxi-
mately five seconds following initial power-up), there is reason to be concerned. If this
occurs, turn the SZ Series 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.
For further assistance, contact your local Samson dealer. If purchased in the United
States, you can call Samson Technical Support (1-800-372-6766) between 9 AM and 5
PM EST.
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