User Guide

DCM250,250
Watt Power
Amplifier
Product Description
The
DCM250
is
a 250 watt
power
amplifier in a two rack
unit
(2RLI)
chassis
suitable for table or direct
19" rack
mounting. The
DCM250
has
outputs for
100 volts
& 4 ohms. It has
a balanced
input of 10K
ohms. The DCM250
will operate
fron 240
VAC
@
50 IIz
or 110 VAC
@
60112
(not
user selectable,
internal, factory
adjushent
only, specify at
the time of
ordering)
or
24
YDC'
and will
meet it's
full
performance
specification
on either voltage
supply.
The
DCM250
also features
a
DC
battery trickle
charge facility,
autosensing
frn cooling,
plus
overload, short
circuit and over t€mperature
protection.
The
maximum
recommended
load
for the DCM250
is
40 ohms.
lnitial Set
Up
There
is
an unlabelled
screwdriver
adjustable output level
control located
centrally
on the
front
panel
of the DCM250.
Turning
this control
in
the clockwise
direction
will increase
the
power
output,
turning this
control
in
a counter-clockwise
direction
will reduce
the
power
output. The factory
default
setting for
this control is such
that a I volt input
will
give
a
100
volt
output.
Front
Panel
Controls
Output
Level: The
output level
control is
unlabelled recessed (scewdriver
adjustable)
and
is located
in
the centre
of the
front
panel,
just
to the right
of the
DCM
Series logo.
Turning the
c.ontrol clockwise will
increase
the ou@ut of
the DCM250
towards
it's maximum
output level while
turning
the control
counter-clockwise will
decrease
the output level.
Adjust this
control
for
the desired
output level
dependittg on
the level
of the input
sigrral
(from
a
mixer
or other
signal
source).
The factory
default
setting fc this
control is
such that
a
I
volt input
will
give
a 100 volt
output.
Powef
Switch:
The
rocker
switch located
in
the front ce,ntre
of the
panel
turns AC
power
on to the DCM250. Rocking
the
power
switch to
the
right
to turns the AC
powetr
'on'.
When the AC
power
is
'on',
a
green
LED will
glow
in
the amplifier
status
display window. Please
note
that
this switch
does not
switch
DC
voltage. If
a
DC
voltage
supply is
connected to the DCM250,
the
amplifier will
o,perate
as stx)n as the
connection
is
made, regardless
of the
position
of the
AC
power
switch.
If
both an AC
and
DC
voltage
supply are
connected and
you
rock
the AC
power
switch
to the
'off
position,
the DCM250
will automatically
continue
to
operate
normally
from the DC
supply
(and
the
'mains
failure'
LED in
the amplifier
status display window will
also
glow
under these
conditions;
see the
amplifier
status
display
window
section under Front
Panel
Controls
later
in this manual).
Cooling
Fans
(Air
lntake): The
cooling fans
(two
installed in the
case of the DCM250)
are temperature
sensitive
and
only
switch on when
the temperature
of
the DCM250 had reached
a
pr+determined
range.
The fans will
stay on and
only switch
off again
once the te,mperature
of the DCM250
has
frllen below
a
pre-determined
level.
So,
the hct that the fans
axe not
operating
at any time
(and
most noticeably
to the
operator at turn-on)
does not mean
that the
amplifier is faulty in
any way,
just
that
it is
operating within
a temp€rature
range
that does not need
frn
cooling for adequate heat
dissipation.
If the DCM250
is
operating
continually
at conservative
levels
and
proper
load conditions,
it is
possible
that the cooling fans
will not switch
on
at
any time
during
normal
operation. Whe,n
operating,
the fans cause
air flow from the front
to the rear
of the DCM250.
Continued noct
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