Operation Manual

FP+ Series Operation Manual 4
3.3 Cooling
The amplier uses a forced-air cooling system with
air ow from front to rear, maintaining a low operating
temperature within dened limits. Front-to-rear air-
ow is preferred as cooler air is present at the front in
nearly all applications. (This allows higher continuous
power levels without encountering thermal problems.)
Never attempt to reverse the airow. The amplier
modules require a pressure chamber between the
fans and heatsink, and this effect functions only in
one direction.
Make sure that there is an adequate air supply in front
of the amplier, and that the rear of the amplier has
sufcient space to allow the exhaust to escape. If
the amplier is rack-mounted, do not use covers or
doors on the front or rear of the rack.
Should a heat sink overheat, the temperature
sensing circuits will mute the overheating channel.
If the power supply overheats, another sensing
circuit will mute all output channels until the power
supply cools to safe operating temperature. An early
warning before shut down will be indicated on the
front panel LEDs, and a warning will be sent through
the NomadLink network.
Always make sure that the dust-lters behind the
detachable front panel are clean to ensure maximum
possible airow.
If the amplier malfunctions due to dirty
dust lters, any required repairs are not
covered by the warranty.
3.4 Operating voltage
The label placed to the right of the mains
cable on the rear of the amplier indicates the
AC mains voltage for which the amplier is wired
and approved: 115 V or 230 V. Connect the power
cable only to the AC source type referred to on the
label. The warranty will not cover damage caused by
connecting to an incorrect type of AC mains.
Lab.gruppen switch mode ampliers use primary
switching. Because the mains power is rectied
directly in front of the transformer, the amplier is
insensitive to mains frequency. It may be connected
to 50 or 60 Hz sources, and actually will operate on
line frequencies from DC to 400 Hz.
If the power plug mounted at the factory is not
appropriate for your country, it can be removed and
the proper connector wired in its place as follows:
BLACK or BROWN LIVE
WHITE or BLUE NEUTRAL
GREEN or GREEN/YELLOW EARTH(GROUND)
If you are not 100% condent of your
competence to replace the mains plug, engage
qualied personnel to do the job.
Once a suitable AC supply is connected, the
amplier can be turned on using the front panel
power switch. The amplier then goes through a
soft-start sequence as it self-checks its circuits. The
fans will blow at high speed before dropping to idle,
and the “power” LED will illuminate.
Inrush power is controlled and limited during “soft-
start”, enabling multiple ampliers to be powered up
simultaneously.
3.5 Grounding
There is no ground lift switch or terminal on the
FP+ Series ampliers. The signal ground is always
oating, via a resistor, to chassis and therefore the
grounding system is automatic.
In the interests of safety, never disconnect the earth
(ground) pin on the AC power cord.
Use balanced input connections to avoid hum and
interference.
INSTALLATION 3