Crown Audio Macro-Tech Series (24x6 & 36x12) - Manual (Page 17)

page 17
Macro-Tech MA-24X6 & 36X12 Power Amplifiers
Operation Manual
5.1 Indicators
The front panel has several helpful indicator
LEDs (Figure 5.1).
The amber Enable indicator is provided to
show the amplifier has been turned on (or
enabled) and that its low voltage power supply
and forced-air cooling system are working. It
does not indicate the status of the high voltage
supplies. For example, the Enable indicator will
remain lit during unusual conditions that would
cause the amplifier’s protection systems to put
a high-voltage supply in “standby” mode (see
Section 4.1.3).
The amber ODEP indicators confirm the nor-
mal operation of Crown’s patented Output
Device Emulation Protection circuitry. During
normal operation, they glow brightly to show
the presence of reserve thermal-dynamic
energy. They dim proportionally as the energy
reserve decreases. In the rare event that there is
no reserve, the indicators turn off and ODEP
proportionally limits the drive level of the out-
put stages so the amplifier can continue safe
operation even when conditions are severe.
(For a more detailed description of ODEP, see
Section 4.1.1).
The ODEP indicator for the affected channel will
turn off if a high-voltage power supply is put in
“standby” mode, a high-voltage power supply
fuse (or breaker) blows, or a transformer acti-
vates its thermal protection circuitry (see Sec-
tion 4.1.4). Both ODEP indicators turn off if the
amplifier loses AC power, the power switch is
turned off or the low-voltage power supply fuse
blows.
The green Signal/IOC indicators show sig-
nal presence, distortion and input overload. As
signal presence indicators, they flash with nor-
mal intensity in sync with the output audio sig-
nals. As IOC (Input/Output Comparator)
indicators, they flash brightly if there is any dif-
ference between the input and output signal
waveforms greater than 0.05%. Because tran-
sient distortion happens quickly, a 0.1 second
“hold delay” keeps the indicators on long
enough to be easily noticed. The IOC function
provides proof of distortion-free performance.
As input overload indicators, they flash brightly
with a 0.5 second hold delay to show that an
input signal is too large and must be clipped at
the input.
Under conditions where one of the amplifier’s
high-voltage power supplies is temporarily put
in standby mode, the Signal/IOC indicators will
stay on with full brightness. They will resume
normal operation when the amplifier is no
longer in standby mode.
The table in Figure 5.2 shows the possible
states for the ODEP and Signal/IOC indicators.
It also describes the conditions that may be
associated with the different indicator states.
The Enable indicator will be off with the first
indicator state, “There is no power to the ampli-
fier.” All other conditions in the table will occur
with the Enable indicator turned on. It is impor-
tant to note the possible states of the indicators
in the rare event that you experience a problem.
This can greatly aid in determining the source
of problems. Please contact your local Crown
representative or our Technical Support Group
for further assistance.
5 Troubleshooting
Figure 5.1Indicators