User manual

User Manual PS 680 / Issue 1 © 1999 ASL Intercom, Utrecht, Holland.
6
8.0 PARTY LINE, TECHNICAL CONCEPT 10.0 TECHNICAL SPECIFICATIONS PS 680
ASL's PRO Series offers a complete two way ('full duplex')
communications system.
Users of the system are connected via a 'party line'.
Master stations (with built-in power supply), beltpacks,
speaker stations and power supplies are interconnected
via standard microphone cable. One wire is used as an
audio line, one as a power line and the screen of the
cable functions as earth/return.
Current drive is used for signal transfer. Each station
utilises a current amplifier to amplify the microphone
signal and place it on the common audio line where, due
to the constant line impedance (situated in the power
supply between XLR pin 3 and 1), a signal voltage is
developed which can be further amplified and sent to
headphones or loudspeakers.
This principle has three advantages:
- the use of a single audio line allows several stations to
talk and listen simultaneously.
- due to the high bridging impedance offered by each
station, the number of stations 'on line' has no
influence on the level of the communications signal.
- power and audio to the intercom stations use the
same cable.
The Call signal is also sent as a current on the audio line.
It develops a DC potential over the line impedance which
will be sensed by each station and interpreted as a Call
signal.
9.0 GUARANTEE
This unit is warranted by ASL Intercom to the original end-
user 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
Zonnebaan 42, 3606 CC Maarssenbroek
Tel. [phone] Fax [phone]
Email : [e-mail]
POWER SUPPLY
mains voltage range 90 - 240 V AC, 50 - 60 Hz
DC output voltage +30 V +/-5% DC
riple and noise < 11 mV rms
max. output current 2 A continuous, 3 A peak
(each channel)
4 A continues, 6 A peak
(total)
circuit-breaker delay time 0.2 sec.
automatic reset time 3.0 sec.
AUX INPUT
input impedance 30 Kohms (balanced line level)
4.6 Kohms (balanced mic level)
nominal input level -18 dBu to +6 dBu (line level)
-38 dBu to -14 dBu (mic level)
max. input level +22 dBu (line level)
+2 dBu (mic level)
phantom power +30 V DC (mic level selected)
DIMENSIONS AND WEIGHT
width 19" (483 mm)
height 1U (44.5 mm)
depth 250 mm
weight 2 Kg
GENERAL SYSTEM SPECIFICATIONS
intercom line impedance 350 ohms (1kHz)
2.2 Kohms (DC)
intercom line audio level nom. -18 dBu
max. +4 dBu
dynamic range 80 dB
call send signal +2.8 mA
call receive signal threshold +2.4 V DC
supply voltage +30 V DC (12 V to 32 V)
mic mute power interrupt time 0.1 sec
Note: 0 dBu = 775 mV into open circuit.
ASL reserve the right to alter specifications without further
notice.