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Operating Manual - Powerflex Multi-Channel 70V Power Amplifier
6.
FRONT PANEL INDICATORS
6.1
Power Switch
When the unit is switched on there is a five sec-
ond delay, during which time the PROTECT circuit will
activate, disconnecting the speakers from the amplifier out-
put. When turning off the amplifier, the load is removed
instantly, and the protect LED will briefly turn on as the
power supply discharges.
6.2
Signal Indicator
The signal present LEDs illuminate at an input
level of about 14mVrms (-35dBu).
6.3
Clipping Indicator
The clipping LEDs illuminate at an input level of
about 870mVrms (+1.0dBu), with all channels driven by
1KHz into rated load. This indicates that the signal pro-
cessing circuitry has determined output levels to be ap-
proaching the available power supply rails and has begun
to "soften" signal peaks. Actual onset of "hard" clipping
depends on audio program and total load impedance and
does not occur until the signal processing circuitry can no
longer compensate, which means that signal integrity can
be maintained even if the clipping indicators illuminate
for short periods of time.
6.4
Thermal Status Indicator
The thermal LEDs illuminate when the tempera-
ture of any one of the heat sink extrusions reaches 85° to
90°C. Both channels of the affected amplifier module will
6
Channel 1
Channel 2
Channel 3
Protect
Thermal
Clip
Signal
Channel 4
Channel 5
Channel 6
shut off until the measured temperature drops below about
70°C. The amplifier should be able to maintain proper
operation at an ambient room temperature of 50°C (122°F)
or less with typical audio program and all channels driven
into rated loads.
6.5
Protect Indicator
The protect LEDs illuminate when the fault moni-
toring microprocessor has determined that one of the fol-
lowing conditions exists:
- Power supply undervoltage
- Power supply overvoltage
- Output overcurrent
- Heat sink overtemperature
- Unacceptable DC output content
- Unacceptable high frequency output content
- AC power interruption
Because the signal processing module used in
Powerflex amplifiers processes two channels simulta-
neously, a fault in one channel will result in a protect con-
dition for both channels processed by the same module,
ex. channels 1-2, 3-4, and 5-6 (670 only). Thus there will
never be a case where only one of the amplifier channels
is shown in protect mode. When a pair of protect LED's
are illuminated, internal relays have removed the channel
pair's speaker loads from the amplifier output and con-
nected the speakers to ground. If the fault is isolated to
one module (channel pair), the other channels will remain
unaffected.
Powerflex
Power
670
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