Allen&Heath WZ14-4-2 MK2 - Manual (Page 10)

10 WZ14:4:2+ U SER G UIDE
NO USER SERVICEABLE PARTS INSIDE.
SUPPLY VOLTAGE RANGE:
100 - 240V
REFER SERVICING TO QUALIFIED SERVICE PERSONNEL.
47-63Hz ~ 30W MAX
WARNING - THIS APPARATUS MUST BE EARTHED.
REFER TO USER GUIDE BEFORE CONNECTING SUPPLY
TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK
DO NOT EXPOSE THIS APPARATUS TO RAIN OR MOISTURE.
AVIS: RISQUE DE CHOC ELECTRIQUE - NE PAS OUVRIR.
REPLACE FUSE WITH SAME TYPE AND RATING
WARNING: FOR CONTINUED PROTECTION AGAINST RISK OF FIRE
ATTENTION: REMPLACER LE FUSIBLE AVEC UN DES MEMES CARACTERISTIQUES.
100 - 240V~ T500mA 250V 20mm
CAUTION
FUSE
OFF
AC MAINS IN ~
ON
~
C
ONNECTING
M
AINS
P
OWER
Refer to the SAFETY WARNING on page 5 of this Guide.
Check that the correct mains lead with moulded plug has been
supplied with your console. Read and understand the
warnings and instructions printed on the rear panel and
reproduced here. The power supply accommodates mains
voltages within the range 100-240V without changing any
fuses or settings.
It is standard practice to turn connected power amplifiers
down or off before switching the console on or off. Ensure
that the IEC mains plug is pressed fully into the rear panel
socket before switching on.
E ARTHING
The connection to earth (ground) in an audio system is important for two reasons:
1. SAFETY - To protect the operator from high voltage shock associated with the AC mains supply
feeding the system, and
2. AUDIO PERFORMANCE QUALITY - To minimise the effect of earth (ground) loops which
result in audible hum and buzz, and to shield the audio signals from interference.
For safety it is important that all equipment earths are connected to mains earth so that exposed
metal parts are prevented from carrying high voltage which can injure or even kill the operator. It is
recommended that the sound engineer check the continuity of the safety earth from all points in the
system including microphone bodies, guitar strings, multicore cases, equipment panels ...
The same earth is also used to shield audio cables from external interference such as the hum
fields associated with power transformers, lighting dimmer buzz, and computer radiation.
Problems arise when the signal sees more than one path to mains earth. An ‘earth loop’ (ground
loop) results causing current to flow between the different earth paths. This condition is usually
detected as a mains frequency audible hum or buzz.
To ensure safe and trouble-free operation we recommend the following:
• Do not remove the earth connection from the console mains plug. The console chassis is
connected to mains earth through the power cable to ensure your safety. Audio 0V is
connected to the console chassis internally. If problems are encountered with earth loops
operate the audio ‘ground lift’ switches on connected equipment accordingly, or disconnect the
cable screens at one end, usually at the destination. It is useful to carry ground lift cable
adapters such as short XLR male to female leads with pin 1 disconnected.
• Avoid running audio cables next to mains, computer or lighting cables, or near thyristor
dimmer and power supply units. If unavoidable, cross these at right angles.
• Use low impedance sources such as microphones rated at 200 ohms or less to reduce
susceptibility to interference. The console outputs are designed to operate at very low
impedance to minimise interference problems.
• Use balanced connections where possible as these provide further immunity by cancelling
out interference that may be picked up on long cable runs. To connect an unbalanced source
to a balanced console input, link the cold input (XLR pin 3 or jack ring) to 0V earth (XLR pin 1 or
jack sleeve) at the console. To connect a balanced console output to an unbalanced
destination, link the cold output to 0V earth at the console.
• Use professional quality cables and connectors and check for correct wiring and reliable
solder joints.
• If you are not sure ... Have your system checked by a competent engineer, or contact your
local Allen & Heath agent for advice.