Samson POWER AMPLIFERS PG3800 - Manual (Page 10)

Setting Up and Using Your PG Series
9. Apply an input signal to the PG Series at or about +4dBu (if sending signal from a mixer,
drive the output meters at approximately 0 vu). While the input signal is present, slowly raise
the Channel Input controls until the desired sound level is achieved. The SIGNAL and CLIP LED
indicators next to each Channel input control will show you the continuous power output of
the PG Series as signal is being passed. For the best signal-to-noise ratio, the PG Series should
normally be run with the Channel Input controls at or near maximum (fully clockwise, at the
“MAX” position) and the CLIP segments should light occasionally (but not frequently) during
peak levels. If you are using a mixer that has a master output level control (sometimes called
“control room level”), use it to attenuate the signal as necessary to achieve the desired speaker
level.
NOTE: If you are operating the PG amplifier at high power levels for long durations in fixed
installations, you may consider switching the operating voltage to 220 volts. A licensed and insured
electrician and/or technician should perform this modification.
If you encounter difficulty with any aspect of setting up or using your PG Series, 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.
The PG Series Protection Circuitry
As noted in the “Guided Tour” section of this manual, the PG Series front-panel Protect
LED indicates the activity of the relay speaker connection circuitry. When the Protect 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 Protect LED to go on:
• Initial power-up: For approximately five seconds after initial power-up, the protection circuit-
ry is activated and the speaker outputs are muted. If everything is operating normally, you will
hear an audible click at the conclusion of this brief period, as the protection circuitry is deacti-
vated and the PG Series begins delivering signal to connected speakers (at which point you’ll
hear a click). It is normal for the Protection LED to fade gradually after the amplifier is powered
off
• Overheating: A temperature sensing device in the PG 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 PG Series receives
adequate ventilation on all sides and that both the front and rear panels are unobstructed.
• Severe overcurrent conditions: This occurs whenever the signal being output from the PG
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 signals
being output by the PG Series are shorted to one another.
• Output impedance drops below 2 ohms: This can occur if the PG Series is connected to inappro-
priate speaker systems (see the “Setting Up and Using Your PG Series” section on page 7 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 Protect LED lights up (other than during the approximately five sec-
onds following initial power-up), there is reason to be concerned. If this occurs, turn the PG
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.
If you encounter difficulty with any aspect of setting up or using your PG Series, 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.
WARNING: If the Protect LED fails to go out (and you fail to hear the accompanying audi-
ble click) approximately five seconds after power-up, turn the PG Series off immediately
and check all external devices and wiring for possible shorts or other defects.
Three-segment LED meter
Protect LED
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