6
M-1500/2000
POWER AMPLIFIER
Protection Circuitry
Protection Circuitry
As noted in the “Guided Tour” section of this manual, the M-1500/2000 front-panel Protection LED indi-
cates 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 0 volts DC), thus protecting them and prevent-
ing 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 protection circuitry is activated and the speak-
er output is muted. If everything is operating normally, you will hear an audible click at the conclusion of
this brief period, as the protection circuitry is deactivated and the M-1500/2000 begins delivering sig-
nal 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.
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 M-1500/2000 off immediately and
check all external devices and wiring for possible shorts or other defects.
- OVERHEATING
A temperature sensing device in the M-1500/2000 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 lev-
el. To guard against this problem, make sure the M-1500/2000 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 input to the M-1500/2000 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 M-1500/2000
short one another.
- OUTPUT IMPEDANCE DROPS BELOW 2 OHMS
This can occur if the M-1500/2000 is connected to inappropriate speaker systems (see the “Setting Up
and Using Your M-1500/2000” 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 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 M-1500/2000 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.
To Next Page
Loading...
Need help?
General
