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power supply
power supply usage
console and power supply grounding
Console chassis ground is electrically connected to:the audio ground,pin-
1 of
XLR connectors, the sleeves of 1/4” sockets,and to the terminal
CON-
SOLE GROUND
at the rear of the power supply.
The AC third-wire connection in the power supply cable connects the
metal chassis of the power supply to safety ground.
Rack-mounting—the power supply ground may transfer to the rack case
through the front fixing screws, though this connection is not reliable.
Sound system use—the grounding requirements may call for the ground
link to be disconnected.This is permissible only when an alternative ground
path has been provided.If in doubt seek the advice of an experienced elec-
trical engineer.
redundant power supplies
The console power supply can be considered the single most important
component in an entire sound system.If a power amplifier,a signal proces-
sor or a console input goes down in the middle of a show, the show can
still go on. But if the console loses its power supply, the show is over. For
this reason, it is always good practice to incorporate redundant power
supplies for mixing consoles used in professional sound reinforcement
applications.
This should be considered a high priority even when using a very reliable
power supply. In even the most carefully designed sound systems, each
component runs the risk of failure at sometime or another.
Crest Audio uses two methods for attaching redundant power supplies to
consoles. In both methods, the two (or more) power supplies should be
kept on while the console is in use to insure a smooth transition in the
event that one shuts off.
If one power supply drops in voltage or shuts off completely,the other unit
takes over without any interruptions or audible glitches.As an added pre-
caution,the two (or more) power supplies can be fed by separate AC lines.
This will guarantee that the console does not shut off if one of the AC lines
goes down.
multiple power supplies in-series
Crest Audio X-Series consoles use this method for backup. Since each
power supply includes voltage switching circuitry,more than two units can
be hooked up in series. A DC link cabel ties the power supplies together.
The use of redundant
power supplies is
probably the single biggest
step that can be taken in
reducing or eliminating the
chance of a cancelled per-
formance due to system
failure.
+
This connection should
never be disturbed.
Hazardous voltages exist
inside the power supply
which require the case to
be grounded.
a
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