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XL4 CIRCUIT DESCRIPTION
1. Earthing System.
The XL4 uses a multiple grounding system to control the interference effects between its internal
digital, analogue audio, analogue fader power and the external systems it is intended to interface
with.
The grounds are marked on the schematics as follows:-
0VA
Analogue zero volts reference which is used for all internal audio circuits, the 48 volt
phantom and twin 18 volt power rails.
0VC
Chassis zero volts which is a SAFETY connection to EARTH for the chassis and also
provides a Faraday screen for the console circuits.
0VD
Digital zero volts reference which is used for all the internal digital circuits and the 5
volt power rail.
0VF
Fader zero volts reference which is used for all fader power circuits, the headphone
amplifier and the twin 15 volt power rails.
0VS
Screen zero volts reference which is connected to all audio input and output sockets
to provide a ground for the cable screens and to provide a return path for the 48 volt phantom on
microphone inputs.
0VA, 0VC, 0VD, 0VF and 0VS are electronically connected at defined points within the console
so as to eliminate circulating currents and interference. Any additional connections between these
points may cause noise problems or digital system failure. 0VA, 0VC, 0VD and 0VS are con-
nected together at the power supply connector distribution board at the back of the console.
0VD and 0VF are connected together at the power distribution board and other points within the
fader tray.
To ensure safety the mains earth must be connected to the console power supply at all
times.
All cables used to connect audio signals or control signals to the console must be terminated with
metal bodied (i.e. screened) connector shells. All Dee type control cables must be high quality
sheilded types with the shield connected to the connector shell. All MIDI cables must be high
quality shielded types with the shield connected to pin 1. All audio cables must be high quality
sheilded twisted pair types with shield connected to pin 1. Any other cable type or configuration
may result in degraded performance due to electromagnetic interference.
2. Power Supply.
The XL4 has an external 3U 19 rack mounted power supply with an auto ranging input for 115
volt or 230 volt nominal operation. It generates six rails to power the console as follows:-
+18 volts at 20 amps
referenced to 0VA
Содержание XL4
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