Advanced Features And Options; Protection Systems; Output Current Limiting; Dc Protection - Crown Xs500 Operation Manual

Xs Series Power Amplifiers
4 Advanced Features
and Options
NOTE: For detailed information about
these Crown amplifier features, please
consult the Crown Amplifier Application
Guide, available on the Crown website
at www.crownaudio.com.

4.1 Protection Systems

Your Crown amplifier provides extensive pro-
tection and diagnostic capabilities, including
output current limiting, microprocessor-con-
trolled DC protection, circuit breaker, and spe-
cial thermal protection for the unit's
transformers.

4.1.1 Output Current Limiting

Output Current Limiting circuitry protects the
amplifier output stage from damage caused by
short-circuit loads.

4.1.2 DC Protection

DC Protection disconnects the loudspeaker
load in the event of an output DC offset exceed-
ing 2V. In such an event the yellow Fault LED
will illuminate (see Figure 4.1) and the ampli-
fier channel will be muted. In the majority of
cases, DC protection is indicative of a faulty
Figure 4.1
amplifier channel, and will be accompanied by
Fault Indicator
an illuminated Clip LED, even with no input
connected and level controls set at minimum. If
this is the case, contact your dealer or service
center.
Operation Manual

4.1.3 Circuit Breaker

The high-voltage power supplies of your Crown
amplifier are protected by a circuit breaker. The
breaker rating varies depending on model and
supply voltage as follows:
Table 2: Circuit-Breaker Amperage Ratings
120V 220V 240V
Xs4300 18A 12A 12A
Xs1200 28A 22A 22A
Xs900 18A 12A 12A
Xs700 18A 12A 12A
Xs500 18A 12A 12A

4.1.4 Thermal Protection

The Thermal Protection circuit will activate if
the internal heatsink temperature exceeds
proper operating temperatures (194 °F, 90 °C).
When the heatsink temperature has fallen to a
safe level, this protection circuit will automati-
cally be reset. Principle causes of thermal pro-
tection are:
1) Inadequate ventilation of the equipment rack
2) Incorrect load impedance
3) Output cable short circuit
4) Blocked air vent
5) Heatsinks in need of cleaning
6) Cooling fan failure.
The cause of your amplifier's thermal protection
state should be determined and corrected as
soon as possible. Without correction, the Ther-
mal Protection circuit will typically reactivate.
page 15