The PS 280 is designed to be a dual channel powerFor each channel separately, the intercom line impedance
supply in an ASL intercom system and can be used incircuitry is installed.
portable as well as fixed applications. It incorporates an
adjustable auxiliary program signal input and uses only 1UFully electronic switching increases reliability and allows
of 19" rack space.for remote Mic Mute facility.
All microphones of the stations connected to the PS 280
The unit is very versatile and ideal for use in applicationscan be muted by pushing a single front panel button.
where standard microphone cable is available and ease of
setup is of paramount importance.An Aux input at the rear panel, allows injecting external
audio signals of line or mic level into the intercom audio
The intercom line power supply is fully protected and canline. When 'mic level' is selected, +30V phantom power is
drive at least 20 beltpacks or 10 speaker stations, or aavailable at the Aux input connector.
combination, operating at full power.
2.0UNPACKING
The shipping carton contains the parts listed below.ASL has taken great care to ensure that this product
*The PS 280reaches you in flawless condition.
*Mains power cableAfter unpacking the unit please inspect for any physical
*Spare fusesdamage to the unit, and retain the shipping carton and
*User manualrelevant packing materials for use should the unit need
returning.
If any are missing contact your dealer.
If any damage has occured, please notify your dealer
With the PS 280 will be a small packet of spare fuses.immediately so that a written claim can be initiated. Please
Please keep them in a safe place.also refer to the guarantee section of this manual.
There is also one spare fuse included in the mains inlet.
3.0MECHANICAL INSTALLATION
A vertical rack space of 1U (1.75", 44mm) is required forThe power supply regulator is mounted on the rear of the
the PS 280. It is not necessary to provide rear support byunit, and after a period of time it will feel hot to the touch.
extra bracing or shelving.This is quite normal, and should be no cause for alarm.
Adequate ventilation must be provided by allowing
sufficient space around the sides and rear of the unit to
ensure free circulation of air. Forced cooling is not
required.
4.0MAINS POWER
The PS 280 may be connected to the mains power outletIf a change is necessary, the internal mains transformer
to which other audio equipment is connected. The outletwiring will need to be reconnected as shown in the figure.
should have a clean earth. Avoid using mains powerRemember that the AC mains fuse will need to be
outlets which also power dimmer controlled lightingchanged for one of the correct rating as indicated in
equipment.section 5.9
Before connecting the unit to its AC power source, checkThe power cord supplied with this unit carries the following
that the mains voltage setting is set in accordance withinformation label:
your local mains voltage. The voltage setting is indicated
by a label on the rear panel.
The wires in this mains lead are colour coded in
accordance with the following code:Setting for 115 V AC
green and yellow2. Empty
Earth / safety ground3. White + Yellow
blue
NeutralSetting for 230 V AC
brown1. Red
Live2. White + Green
As the colours of the wires in the mains lead may not
correspond with the coloured markings identifying the
terminals in your plug, proceed as follows:
-The wire which is coloured green-and-yellow must be
connected to the terminal in the plug which is marked
with the letter "E", or by the earth symbol which is or
coloured green.
-The wire which is coloured blue must be connected to
the terminal which is marked with the letter "N" or
coloured black.
-The wire which is coloured brown must be connected
to the terminal which is marked with the letter "L" or
coloured red.
Transformer Voltage settings (Internal)
1. Red + Green
3. Yellow
Voltage:
Voltage:
Those units that are supplied to the North American
market will have an integral moulded 3 pin connector
which is provided to satisfy required local standards.
4.1SAFETY EARTHING
The green-and-yellow wire of the mains cord must alwaysThe PS 280 employs professionally designed audio input
be connected to the electrical installation safety earth orand output circuits which do not require the disconnection
ground. It is essential for personal safety as well for properof any safety earth for the avoidance of hum loops.
operation of the PS 280 and the other connected stations.
This wire is internally connected to all exposed metal
surfaces and any rack framework into which this unit might
be mounted is assumed to be connected to the same
grounding circuit.
4.2POWERING UP
Powering up procedure:
-Make sure that the red power switch on the left sidePROPERLY GROUNDED outlet.
of the front panel is OFF.
-Connect the power cord to the rear of the station.
-Turn on the power with the red button. The red
overload LED will light up for about 3 seconds, then
extinguishes and then the green power LED will go
on, indicating the station is active.
See for further installation and operation the concerning
sections.
Mains power push button for switching ON and OFFThis LED illuminates if line power is supplied by the
the internal power supply.internal power supply.
2 OVERLOAD LED4 ALL MIC'S ON/OFF button
This LED illuminates if the internal power supply hasWith this pushbutton all microphones of the connected
shut off line power due to overload.stations can be muted.
If the internal power supply is overloaded (too many
user stations are connected or short-circuit in the
interconnecting cables or thermal overload), it activatesWith this button all buzzers of the connected stations
a circuit-breaker which immediately shuts off linecan be muted.
power. This circuit breaker resets automatically 3
seconds after the overload situation is terminated,
restoring line power automatically.These knobs adjusts the level of the aux input signal to
During short-circuit, the overload LED extinguisheseach of the two intercom lines.
very shortly every 3 seconds. During thermal overload
the LED burns continuously.
This overload LED also comes on every time you
switch on the main power.
5 ALL BUZZERS ON/OFF button
6 AUX VOLUME control knobs
6.0REAR PANEL CONTROLS & CONNECTORS
7 A & B LINE connectors9 FUSE
These XLR-3 type connectors are for connecting userThis fuse protects the PS 280 against severe internal
stations, via standard microphone cable.damage, in case of malfunction in the power section.
There are two connectors for channel A and twoTo remove the fuse the mains cord must be removed.
connectors for channel B.
It is most important to place the correct fuse in the
Pin assignments :holder :
1. 0 V / ground shieldmains voltage
2. +30 V power wirefuse
3. audio wire220 - 240 VAC T 315 mA
100 - 120 VAC T 630 mA
8 AUX INPUT connector
This XLR-3 type aux input is electronically balancedSpare fuses will be found in the small packet supplied
and accepts audio levels between -18dBu to +22dBuwith the unit.
on line level, and -38dBu to +2dBu on mic level.
10 MAINS INLET
Pin assignments :IEC Mains connector. For correct wiring and operation
1. 0V / groundrefer to section 4.0.
2. Signal +
3. Signal -
When mic level is selected, a +30V DC phantom power
is supplied to pins 2 and 3.
For the PRO Series Intercom system the interconnecting
cables are of the shielded two-conductor microphone
cable type and the intercom line connectors are of the
XLR-3 type. Audio and Call signals are on XLR pin 3, DC
power is on XLR pin 2. XLR pin 1 is connected to the
shield of the cable which functions as the common return
for audio and power.
Since the audio signal is transferred in an
way, certain rules have to be obeyed when installing the
cables of an intercom network. This in order to avoid earth
loops and to minimize power loss and the possible effect
of electromagnetical fields.
These rules are:
Use high quality (multipair) cable.
For interconnecting user stations, power supplies andWhen two (multi channel) units in a network are
accessories in an ASL Intercom network, use highconnected by more than one cable, make sure that
quality shielded two-conductor (minimum 2x 0.30 mm2)these cables are parallel to each other over the whole
microphone cable only.distance between those units. When using multipair
In case of a multi channel intercom network, use highcable, parallelism is ensured in the best possible way.
quality microphone 'multipair' cable only, each pair
consisting of two conductors (minimum 2x 0.15 mm2)
with separate shield. Multipair cable should have anAlways avoid that cables are making a loop. So-called
overall shield as well.'ring intercom' should not physically be cabled as a
Use flexible cables.
Use flexible single and multipair microphone cablepower supply position) as the center of the star.
instead of cable with solid cores, especially when the
cable is subjected to bending during operation or
installation.Keep intercom cables away from high energy cables,
Separate cable screen to XLR pin 1.
The screen of each separate microphone cable and/orIntercom cables should cross with energy cables in an
the screen of each single pair in a multipair cable,angle of 90( only.
should be connected to pin 1 of each XLR-3 connector.Intercom cables should never be in the same (metal)
Do not connect this cable screen to the metal housingtrunks with energy cables.
of the connector or to metal wall boxes (outlets).
See last page for Earthing Concept.
Cable trunks, connection boxes and overall
multipair cable screen to clean earth.
Metal cable trunks, metal connection boxes and overalluser stations are placed.
multipair cable screen should be interconnected and,
at one point (the 'central earthing point') in the intercom
network only, be connected to a clean earth or a safety
earth.The ASL power supply may be connected to the mains
See last page for Earthing Concept.power outlet to which other audio equipment is
Keep metal connection boxes and cable trunks
isolated from other metal parts.
Metal housings for intercom cables and connectorsIn case of more complex installations, don't hesitate to
should be mounted in such a way that they are isolatedcontact us. Please send us a block diagram of the planned
from other metal cable and connector housings andnetwork with a list of all user stations and their positions,
from any other metal construction parts.and we are happy to advise you on cabling lay out.
unbalanced *
Keep cables parallel as much as possible.
Avoid closed loops.
ring. All cable routes should have a 'star' configuration,
with the central earthing point (usually close to the
Keep cables away from electromagnetical sources.
e.g. 110/220/380V mains power or dimmer controlled
feeds for spotlights.
Place power supplies in a central position.
In order to avoid unacceptable power losses, place the
power supplies as close as possible to where most
power consumption occurs or, in other words, most
Connect ASL power supply to a 'clean' mains
outlet.
connected. Avoid using mains outlets which also power
dimmer controlled lighting systems.
ASL's PRO Series offers a complete two way ('full duplex')
communications system.mains voltage range115 V units: 100 - 125 V 60Hz AC
Users of the system are connected via a 'party line'.230 V units: 210 - 250 V 50Hz AC
Master stations (with built-in power supply), beltpacks,DC output voltage+30 V +/-5% DC
speaker stations and power supplies are interconnectedriple and noise< 11 mV rms
via standard microphone cable. One wire is used as anmax. output current1.7 A continuous, 3 A peak
audio line, one as a power line and the screen of the cablecircuit-breaker delay time0.2 sec.
functions as earth/return.automatic reset time3.0 sec.
Current drive is used for signal transfer. Each station
utilises a current amplifier to amplify the microphone signalinput impedance30 Kohms (balanced line level)
and place it on the common audio line where, due to the4.6 Kohms (balanced mic level)
constant line impedance (situated in the power supplynominal input level-18 dBu to +6 dBu (line level)
between XLR pin 3 and 1), a signal voltage is developed-38 dBu to -14 dBu (mic level)
which can be further amplified and sent to headphones ormax. input level+22 dBu (line level)
loudspeakers.+2 dBu (mic level)
This principle has three advantages:
-the use of a single audio line allows several stations towidth19" (483 mm)
talk and listen simultaneously.height1U (44.5 mm)
-due to the high bridging impedance offered by eachdepth150 mm
station, the number of stations 'on line' has noweight2.55 Kg
influence on the level of the communications signal.
-power and audio to the intercom stations use the same
cable.intercom line impedance350 ohms (1kHz)
The Call signal is also sent as a current on the audio line.intercom line audio levelnom. -18 dBu
It develops a DC potential over the line impedance whichmax. +4 dBu
will be sensed by each station and interpreted as a Calldynamic range80 dB
signal.call send signal+2.8 mA
POWER SUPPLY
AUX INPUT
phantom power+30 V DC (mic level selected)
DIMENSIONS AND WEIGHT
GENERAL SYSTEM SPECIFICATIONS
2.2 Kohms (DC)
call receive signal threshold+2.4 V DC
supply voltage+30 V DC (12 V to 32 V)
mic mute power interrupt time0.1 sec
9.0 GUARANTEE
This unit is warranted by ASL Intercom to the original enduser purchaser against defects in workmanship and
materials in it's manufacture for a period of one year from
the date of shipment to the end-user.
Faults arising from misuse, unauthorised modifications or
accidents are not covered by this warranty. If the unit is
faulty, it should be sent in it's original packing to the
supplier or your local ASL dealer, with shipping prepaid. A
note must be included stating the faults found and a copy
of the original suppliers invoice.
THIS PRODUCT WAS DESIGNED, DEVELOPED AND
MANUFACTURED BY:
AMPCO SOUND LAB BV, MAARSSEN (UTRECHT),
HOLLAND
Note: 0 dBu = 775 mV into open circuit.
ASL reserve the right to alter specifications without further
notice.