User Guide
DCM120,12O
Watt
Power
Amplifier
Product Description
The
DCM120
is
a 120
watt
power
amplifier in
a two rack
unit
(2RI)
chassis suitable for
table
or direct 19" rack
mounting.
The
DCM120
has
outputs for 100
& 70 volts, 4
& 8 ohms. It has
a balanced input
of
10K
ohms. The DCMI2O
will
operate
from 240
V AC
@
50 tlz
or I I
0 VAC
@
60
llz
(not
user
selectable, internal,
facrory
adjusnne,nt
only, specify
at the time
of ordering)
or 24 YD(,
and
will meet
it's
frrll
poformance
specification
on
either voltage supply.
The DCMI2O
also features
a
DC
battery
tickle
charge facility,
auto-sensing
fan
cooling,
plus
overload,
shrt circuit and
over temperature
protection.
The
maximum
recommended
load
for the
DCM120
is
80 ohms.
lnitial
Set Up
There is
an unlabelle4
screwdriver
adjustable
output level
contol located
curfrally
on the
front
panel
of the DCMI20.
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
conhol is such
that a I volt input
wilt
give
a
100
volt
output.
Front
Panel
Controls
Output
Level: The
output level
control is
unlabelled
recessed
(screwdriver
adjustable)
and
is located
in the
centre of
the
front
panel,
just
to the right
of the DCM
Series logo. Turning
the
control
clockwise will increase
the output
of the DCM120
towards it's
maxim'm
output level
while
turning
the
control cormter-clockwise
will decrease
the output level.
Adjust
this contol
for the
desired
output level
depending
on the level
of the
input
signal
(from
a
mixer
or
other sigrraisource).
fni factory
default
setting for
this control is
zuch that a 1
volt input
will
give
a 100
volt output.
Power
Switch: The rocker
switch
located
in
the front
centre of the
panel
turns AC
power
on to the DCMI20.
Rocking
the
power
switch
to the right
to
turns the
AC
pow€tr
'on'. When the AC
power
is
'on',
a
gre€n
LED
will
glow
in
the amplifio
status
display window.
Please
note
that this
switch
does not
switch DC voltage.
If a DC voltage
supply is
connected to
the
DCMI20,
the
amplifier
will operate
as
soon as the
connection
is madg
regardless
of the
positim
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 DCM120
will
automatically
continue
to op€rate 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
Confols later in
this
manual).
Cooling
Fans
(Air
lntake):
The
cooling
ftn
is
temperature
sensitive
and will only switch
on
when
the tqnp€rature
of
the DCMI2O
had reached
a
predetermined
range.
The
fan will
stay on and only
switch off
again once the temperature
of the
DCM120
has
frllen below
a
pre-determined
level.
So, the hct
that the frn is not
operating
at anytime
(and
most noticeably
to the
op€rator
at turn-ur)
does not man
that
$s
emplifia
is
ftulty
itt
any way,
just
that
it is
op€rating
within a
t€mp€rature
range
that
does not need
ftn
cooling for
adequate
heat
dissipation.
If the DCMI2O
is
operating continually
at conservative levels
and
froper
load
cmditions, it is
possible
that
the cooling
frn will not
switch on
at any time during normal
operation. When operating,
the
ftn cause
air
flow
from
the front
to the rear
ofthe
DCM120.
Continued
noct
page3