AUSTRALIAN MONITOR DCM120 User manual

DCM120
120w Power Amplifier
Operating Manual
TEMP FAILON 24 21 18 15 12 9 6 3 0 +3
HI MAINS
DCM 120

ProductDescription
TheDCM120 isa 120watt poweramplifier designedfor commercialinstallations. Itcan beused foreither lowimpedance
(4 or 8 ohm) or 70v/100v line speaker systems. The amplifier can be mounted in a standard 19” equipment rack or it can
beused ona shelfor table.The DCM120features aline levelinput (withparallel output)and isnormally usedwith mixers,
mixer amplifiers or other power amplifiers. The DCM120 will operate from 230/240 VAC @ 50 Hz (115 VAC @ 60
Hz with factory modification) or 24 VDC and will meet its full performance specification on either voltage supply.
The DCM120 also features a DC battery trickle charge facility, auto-sensing fan cooling, plus overload, short circuit
and over temperature protection.
DCM120, 120 Watt Power Amplifier
Front Panel Features
Power Switch
The rocker switch located in the front centre of the panel turns AC power on to the DCM120. Rocking the power switch
to the right to turns the AC power ‘on’. When the AC power is ‘on’, a blue LED will glow. Please note that this switch
does not switch DC voltage. If a DC voltage supply is connected to the DCM120, the amplifier will operate as soon
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 DCM120 will automatically continue to
operate normally from the DC supply (and the ‘mains failure’ LED will also glow under these conditions).
Level Control
The output level control is located in the centre of the front panel, just to the left of the mains rocker switch (re-
cessed screwdriver adjustable pot). Turning the control clockwise will increase the output of the DCM120 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 depending on the level of the input signal (from a mixer or other signal source).
The factory default setting for this control is such that a 1 volt input will give a 100 volt output.
AmplifierStatusDisplay
The amplifier status display highlights the operating condition of the DCM120. The status display indicates:
High Temperature: This red LED glows if the fan has failed and the amplifier has been shut down by its temperature
control circuitry. If this LED is glowing and the fans have not failed, it means that the amplifier is operating in an ambient
environment that is too hot for fan cooling to make any difference to the temperature of the amplifier.
Power: This LED glows blue if AC power is switched on to the DCM120. Note that this LED does not indicate the
presence of a DC supply voltage.
TEMP FAILON 24 21 18 15 12 9 6 3 0 +3
HI MAINS
DCM 120

Rear Panel Features
AC Power Inlet
The 3 pin IEC power inlet is located on the bottom left of the rear panel and accepts a standard mains power lead fitted
with an IEC connector. Before plugging in a power lead, please check the rear panel of the amplifier to ensure that the
voltage label shows the correct AC operating voltage for your part of the world.
The inlet is equipped with an in-built AC fuse holder fitted with a 4 Amp slow blow fuse plus a spare fuse. Pleaseensure
thatthe mainspower cordis disconnectedbefore attemptingto checkor replacethis fuse.Powerconsumption is300
VA(max).
Speaker Output Terminal Strip
Located on the top left of the rear panel is the speaker output terminal strip. Reading from left to right, the connections
are: COM Common or “-” for low impedance speaker loads (4 or 8 ohms).
4The “+” for 4 ohm speaker loads (use with common)
8The “+” for 8 ohm speaker loads (use with common)
COM Commonor “-” for70v or100v speakerloads (maximum loadof 80ohms at100v)
70 The “+” for 70v line speaker loads (use with common)
100 The “+” for 100v line speaker loads (use with common)
Please ensure that the correct “Common” is used. Low impedance and 70/100v loads can be used simultaneously but
please pay careful attention to the overall speaker load. When used individually, the low impedance load should be 4
ohms or higher while the 100v line load should not fall below 80 ohms. When both outputs are used simultanously,
ensure that neither output is loaded to maximum.
24 Volt Power
Located on the rear panel are the red and black connection posts for 24v power. This feature can be used as either a back-
up facility (if mains power fails) or for applications where AC power is not available. The left side red post is the +
(positive) terminal while the right side black post is the -(negative) terminal. The DC current drain is 8 Amps maximum
at full power. This socket also provides trickle charge to a DC battery supply (if connected) when the DCM120 is
operatedfrom AC mainspower.The levelof trickle charge is300 mA,maximum.
MainsFailure: The LED glows red if there is a failure in the AC mains power supply. However, this LED will only glow
if there is a DC supply voltage present. If no DC supply voltage is present then this LED will not glow.
OutputLevelVU Meter:A 10 segment LED VU meter is provided to give an indication of the output signal level of the
amplifier from -25 to +3 dB. During normal operation, the LED’s will oscillate with changes in the program signal. Care
should be taken to avoid more than occasional illumination of the red LED’s. If the LED’s in the red zone are lit
continually, then the output level control (or the level of the input signal to the DCM120) should be adjusted to reduce
the output level. Too much output level can cause distortion, activate the internal limiter or possibly damage the
connected speaker system.
230 V 240 V
CC41008
OHM VOLT
70
AC FUSE 4A S/B
ENGINEERED BY AUDIO TELEX COMMUNICATIONS PTY LTD SYDNEY AUSTRALIA
DC FUSE
10A S/B
24 VDC
INPUT

DC Fuse Receptacle
Located on the rear panel is the DC fuse receptacle. Access the DC fuse by turning the cap counter-clockwise with a
screwdriver. The value of the fuse is 10 Amps. Please ensure that the AC power switch is in the ‘off’ position
and that the mains power cord is disconnected before attempting to check or replace this fuse
Cooling Fan (Air Intake)
Thecooling fan istemperature sensitiveand will onlyswitch onwhen the temperatureof theDCM120 hadreached a pre-
determined range. The fan will stay on and only switch off again once the temperature of the DCM120 has fallen below
a pre-determined level. If the DCM120 is operating continually at conservative levels and proper load conditions, it is
possible that the cooling fan will not switch on at any time during normal operation. When operating, the fan works with
air flow from the front to the rear of the DCM120.
Fuse Sizes
Mains,240VAC: 4Amperes Slow Blow.
XLR Audio Input and Parallel Output
The input to the DCM120 is transformer balanced @ 10K ohms. When signal is connected to one XLR, the other
XLR becomes a line level output allowing the input signal to be distributed (split) to other amplifiers. In some
projects, the same input may be looped through to multiple amplifiers using this method. Up to 6 amplifiers can be
looped together without any noticeable loss in level. A distribution amplifier should be used when more than 6
amplifiers need to be looped.
The XLR’s are wired as follows: Pin 1: Shield. Pin 2: Hot, +, Positive. Pin 3: Cold, -, Negative

1.Savethecartonandpackingmaterialeveniftheequip-
ment has arrived in good condition. Should you ever
need to ship the unit, use only the original factory pack-
ing.
2.Readalldocumentationbeforeoperatingyourequip-
ment.Retain all documentation for future reference.
3. Follow all instructions printed on unit chassis for
proper operation.
4.Donotspillwaterorotherliquidsinto orontheunit,
or operate the unit while standing in liquid.
5. Makesurepower outlets conformto the powerre-
quirements listed on the back of the unit.
6. Do not use the unit if the electrical power cord is
frayed or broken. The power supply cords should be
routed so that they are not likely to be walked on or
pinched by items placed upon or against them, paying
particular attention to cords and plugs, convenience re-
ceptacles, and the point where they exit from the
appliance.
7. Always operate the unit with the AC ground wire
connected to the electrical system ground. Precautions
should be taken so that the means of grounding of a
piece of equipment is not defeated.
8.Mains voltagemustbecorrectand thesame asthat
printed on the rear of the unit. Damage caused by
connection to improper AC voltage is not covered by
any warranty.
9.Havegaincontrolsonamplifiersturneddownduring
power-up to prevent speaker damage if there are high
signal levels at the inputs.
10.Powerdown&disconnectunitsfrommainsvoltage
beforemaking connections.
11.Neverholdapowerswitchinthe“ON”positionif it
won’tstay thereitself!
12.Do not usethe unit nearstoves,heat registers,ra-
diators,orotherheatproducingdevices.
13. Donot blockfanintake orexhaust ports.Donot
operate equipment on a surface or in an environment
which may impede the normal flow of air around the
unit, such as a bed, rug, weathersheet, carpet, or com-
pletelyenclosed rack.If theunitis usedin anextremely
dusty or smoky environment, the unit should be peri-
odically “blown free” of foreign matter.
14. Donotremovethecover.Removingthecover will
expose you to potentially dangerous voltages. There
are no user serviceable parts inside.
15.Donot drivetheinputs withasignal levelgreater
thanthatrequiredtodriveequipmenttofulloutput.
16. Donot connectthe inputs/ outputsof amplifiers
or consoles to any other voltage source, such as a
battery, mains source, or power supply, regardless of
whether the amplifier or console is turned on or off.
17. Donotrun the output ofanyamplifierchannel
backintoanotherchannel’sinput.Donotparallel-or
series-connect an amplifier output with any other
amplifieroutput.
Audio Telex Communications Pty Ltd is not respon-
sible for damage to loudspeakers for any reason.
18. Donotground any red(“hot”)terminal. Never
connecta“hot”(red)outputtogroundortoanother
“hot”(red)output!
19. Non-use periods. The power cord of equipment
should be unplugged from the outlet when left un-
used for a long period of time.
20.ServiceInformationEquipmentshouldbeserviced
by qualified service personnel when:
A. The power supply cord or the plug has been
damaged.
B. Objects have fallen, or liquid has been spilled into
the equipment
C. The equipment has been exposed to rain
D.The equipmentdoes notappear tooperate normally,
or exhibits a marked change in performance
E. The equipment has been dropped, or the enclosure
damaged.
Important Safety Information

Engineered by Audio Telex Communications Pty Ltd, Sydney, Australia
A.B.N. 78 001 345 482 Inc in NSW
Sydney (NSW & ACT Sales)
Private Bag 149, Silverwater NSW 1811
149 Beaconsfield Street, Silverwater NSW 2128
Ph: [phone]
Fax: [phone]
E-mail: [email protected]
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P.O. Box 871, Fortitude Valley QLD 4006
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31 Walsh Street, Thebarton SA 5031
Ph: [phone]
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P.O. Box 404, North Perth WA 6906
299 Fitzgerald Street, West Perth WA 6005
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P.O. Box 512, Albany 1331
Unit B, 11 Piermark Drive, Albany 1331
Ph: [phone]
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E-mail: [email protected]
ExportSales &Corporate HeadOffice
Private Bag 149, Silverwater NSW 1811
149 Beaconsfield Street, Silverwater NSW 2128
Australia
Ph: 61-2- 9647 1411
Fax: [phone]
E-mail: [email protected]
www.audiotelex.com.au