Filter Cleaning - Crown Macro-Tech MA-1200 Reference Manual

Macro-Tech 600/1200/2400 Power Amplifiers
standard 1-kHz power, the middle position provides
26 dB gain, and the back position sets the
sensitivity to 0.775 volts for standard 1-kHz power.
5. Replace the PIP module and reconnect the power
to the amplifier.
The Ground Lift switch is located on the back panel
and can provide isolation between the input signal
grounds and the AC (chassis) ground. It affects only
the phone jack inputs and has no affect on the PIP mod-
ule input connectors. Sliding the switch to the left iso-
lates or "lifts" the grounds by placing an impedance
between the sleeve of each input phone jack and the
AC power ground.
The noninverted and inverted signal lines for the PIP
module are connected in parallel with the correspond-
ing lines of the phone jack inputs. The input signal
grounds are not paralleled. Specifically, XLR pins 2 and
3 are connected in parallel with the tip and ring of the
corresponding phone jack. However, pin 1 of the XLR
is not connected in parallel with the sleeve of the phone
jack. This makes it possible for a PIP module to handle
its own signal grounds independently.
Reference Manual
The Macro-Tech 2400 has back panel Reset switches
that are used to reset the breakers that protect the high-
voltage power supplies from overload. If a breaker trips,
the IOC indicator for the affected channel will turn on
(see Figure 4.2).

4.5 Filter Cleaning

Dust filters are provided on the air intakes to the cooling
system (see Figure 2.1). If these filters become
clogged, the unit will not cool as efficiently as it should
and may produce output levels that are lower than nor-
mal due to high heat sink temperature.
To clean, remove each of the filter elements by gently
pulling them away from the front panel. Clean with mild
dishwashing detergent and warm water. Replacement
filters may be ordered from the factory.
Dust filters are not 100% efficient—depending on the
local environment, the internal heat sinks of the ampli-
fier will benefit from periodic cleaning by a qualified
technician. Internal cleaning information is available
from our Technical Support Group.
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