IEC INLET/ FUSE - the power inlet is on the lower face and is held in place by a
spring clip to ensure that the mains (IEC) connector is firmly retained. The mains lead
is supplied complete with a national mains plug. Pageman is not equipped with a
mains switch since it is intended for use in permanently powered applications. If it is
necessary to control the power to Pageman, a suitably rated mains switch should be
used. A variety of suitable switch-plates are suitable for this purpose. The IEC inlet
includes an integral fuse, in this case fitted with a 1A time lag fuse. WARNING - the
mains plug and the IEC inlet plug must be removed, and the unit isolated from the
mains supply, before attempting to check or replace this fuse. Use the same type and
size fuse - 1A time lag, 20mm.
1.1 Internal features
Before gaining access to the internal parts of Pageman , please ensure that the
incoming mains power supply is isolated by removal of the mains plug. WARNING PAGEMAN has unprotected internal parts that would be operating at hazardous
voltages, these parts are not immediately obvious, particular caution must be given to
the following:
a) The wiring around the IEC connector will be carrying mains voltages.
b) The output transformers, and potentially parts of the PCB may be at 100V line
level.
THE ABOVE ARE CLASSIFIED AS HAZARDOUS VOLTAGES !
c) The heatsink is isolated from the chassis and operates at a potential of -35V dc,
whilst this is classified as a low voltage, substantial current can be supplied and care
must be taken to ensure that the heatsink is not connected to chassis.
Figure 2 on the following page shows the general internal layout and location of
fuses, terminals and connectors on the PCB.
1.1.1 General features
The following summary is for details provided on Figure 2:
CABLE ENTRY (LOUDSPEAKER CIRCUITS) - the bottom left cable entry hole is
intended for the cables to each of the loudspeaker circuits. These cables should be
segregated from low level cables, such as cables to paging microphones and music
source equipment.
ZONE 1 (L) OUTPUT TRANSFORMER - output from the PCB is conventional low
impedance, and may be used to drive low impedance (4ohm to 16ohm) loudspeakers
directly. Public Address equipment for distributed sound is often required to drive a
100V line system for more efficient sound distribution over small cross section cables
and large distances, typically encountered in industrial/ commercial building systems.
Output from the PCB (at low impedance) is connected to the output transformer
primary. The transformer increases the PCB voltage by a ratio of almost five times, to
achieve the 100V line level. The transformer secondary is arranged as two winding of
0 - 50V, 0 - 50V; and generally it is necessary to ‘series’ these windings according to
Figure 3.
A number of possible output configurations are possible, and these are summarised in
the table below:
Output configuration
100V line (balanced)
100V line (floating)
100V and low impedance
50V line
Low impedance only
100V or 50V line at 100W
using Zone 1 and Zone 2
Description
This is the most common form of distribution, and Figure 3 shows
how the transformer is wired. Pageman is shipped in this
configuration, ready for the loudspeakers to be terminated to the
terminal block at the side of the transformer.
Sometimes preferred since a single fault to earth will not affect
performance, but this arrangement is prone to interfere with adjacent
telephone circuits. The connection to earth in Figure 3 is not fitted.
It is possible to simultaneously operate low impedance loudspeakers
and 100V line loudspeakers. The low impedance loudspeakers are
connected in parallel with the 100V line transformer primary, i.e.. at
the PCB terminal block. Care must be taken to ensure the correct
loading on the power amplifier. As a rough guide, the following limits
apply:
4 ohm loudspeaker load (approx.. 70 Watts) with 7 watt 100V load, or
8 ohm loudspeaker load (approx.. 40 Watts) with 25 watt 100V load,
or
15 ohm loudspeaker load (approx.. 20 Watts) with 40 watt 100V load.
REMEMBER: low frequency roll off must be set to 80Hz with output
transformers connected. Please refer to section 5.4.4 for further details.
In all instances where 100V line is stated, it is possible to set the
output as a floating 50V line.
The 100V line transformer should be disconnected from the PCB, and
loudspeaker output should then be taken directly from the PCB
terminals. When the 100V line transformer is disconnected, additional
output power will be achieved, and if HD14 (Zone 1) and/ or HD15
(Zone 2) are fitted the low frequency response of the amplifier may be
extended. Please refer to section 5.4.4 for further details.
The independent power amplifiers of Zone 1 and Zone 2 may be
coupled together via their output transformers, to create a single 100
Watt output circuit. N.B.. 100V / 50V line only. Please refer to section
6.6. for further details.
Figure 1 - Internal layout
Figure 2 - Output transformer connections
ZONE 2 (R) OUTPUT TRANSFORMER - the arrangement is identical to that of
Zone 1. The two output circuits are totally independent, unless the outputs are to be
joined together to make one common 100 Watt output circuit, in accordance with
instructions in section 6.6
CABLE AND CONNECTOR ENTRY (MUSIC) - the upper cable entry hole is
intended for the PHONO connectors and leads from the music source equipment.
MUSIC INPUT - LEFT & RIGHT (CON4 and CON5, RCA PHONO SOCKETS) the two PHONO sockets will normally be connected using a proprietary lead from the
music source equipment (CD player, tuner etc...). A variety of configuration
possibilities exist, in accordance with the following table:
Configuration
Mono signal from a single
source
Stereo signal from a
single source
Mono signal, two music
sources
No music
Description
The music source equipment will most probably have a stereo output.
Using a stereo connecting lead, with HD11 fitted in positions a-b, the
stereo input signal will be combined to become mono. The level and
equalisation of music may be set independently in Zone 1 and Zone 2.
Pageman may operate in true stereo mode, HD11 must be set to
position b-c. The level and tone controls for the music input will be set
the same for each channel Left (Zone 1) and Right (Zone 2)
It is possible to operate two different music sources, independently on
each zone. In this case the input will be converted to mono before
connection is made to Pageman. HD11 will be set to position b-c, the
music signal for Zone 1 will be connected to CON4, and Zone 2 signal
will be connected to CON5.
With no background music, the MUSIC level controls should be set to
their minimum position.
CABLE AND CONNECTOR ENTRY (PAGING MICROPHONES) - the bottom
right cable entry hole is intended for the cables from the paging microphones.
Microphone 1 (highest priority) connects to a 8 pin DIN socket whereas microphone 2
is to connected via the terminal block. This arrangement is provided since it is
assumed that microphone 1 will be local (within 2 metres) of the Pageman enclosure,
and that microphone 2 will be distant. The lead and DIN plug of microphone 1 may
pass through the cable entry hole, the DIN plug connects directly to the PCB socket.
MICROPHONE 1 INPUT (8 PIN DIN CONNECTOR - CON1) - the 8 pin DIN
connector is designed to accept direct connection from a Whiteley 1476/PM two zone
paging microphone. Microphone 1 input is highest microphone priority, but this is
below the priority of the tone generator option (if fitted). The following table
identifies the pin allocations of the 270 8 pin DIN connector:
PIN
1
2
3
4
5
6
7
8
FUNCTION
M1 microphone in-phase input
0V, system ground, screen
M2
microphone out-phase input
Zone 1 Request (access)
Zone 2 Request (access)
L1
line in-phase input
L2
line out-phase input
Speak now/ chime indicator
MICROPHONE 2 INPUT (8 WAY TERMINAL BLOCK - CON2, AND 8 PIN DIN
- CON3) - the 8 way terminal is designed to accept a cable extended from a Whiteley
1476/PM two zone paging microphone. The remote microphone, through its 8 pin
DIN plug will normally be interfaced to the installation cable via a Whiteley WP101
wall connection unit. Microphone 2 input is lowest microphone priority, but this is
above the priority of the music input (used). The order of terminals on CON2 and the
pinout of CON3 is the same as the pin number allocations of the 270 8 pin DIN CON1, given in the table above.
AUX. 24V/ 0V (3 WAY TERMINAL BLOCK - CON12) - this block is at the top of
the PCB, adjacent to the ‘right’ channel PHONO socket. This set of terminals is part
of a large strip, but the left most terminals are described here. The AUX. dc supply is
primarily intended for powering of interfaces to other products, such as Speak n’ store
and Teliport. The left most terminal is 24V dc, a maximum current of 150mA may be
consumed from this terminal. Protection of this supply is provided by FS1 (0.25A),
but it should be noted that excess current through this terminal, causing FS1 to
rupture, will affect all pre-amplifier and control functions within Pageman. The
second and third terminals are connected to ground (0V).
Figure 3 - PCB details