14
2120 Audio System Upgrade,
Continued
Overview
The migration of the BMUX requires that Flex-35 amplifiers configured as power preamplifier(s)
in the programmer (amplifier setup screen) be used to replace the power preamplifiers located in
the adjacent SCC. The Power preamplifiers generate a 25V riser signal that is compatible with
25V supervision signal, and ignores shorts and opens on these circuits. Trouble supervision of the
riser is reported by the receiving amplifiers.
In order to insure that the 2120 Audio Riser is capable of generating an earth fault trouble, the riser
NAC (-) is connected to 0V shield through a 1K resistor (part number 733-973) in class B systems
for which there is no system 0V reference. See the
2120 BMUX to 4100U Migration Guide
(579-824)
for information regarding riser amplifier wiring on the 4100U that also applies to the
4100ES.
Class A Risers
In a BMUX system, Class A risers are supervised by a Class A Audio Monitor (assembly
617-278) mounted to the 2120 riser amplifiers located in the adjoining SCC cabinet. This device
detects the loss of an audio signal on the class A return lines, and automatically turns on the class
A relay to drive both sides of the riser in the event of a fault. The Class A audio monitor card uses
one control and one monitor point on the BMUX local BT. The monitor point is used to detect the
Class A trouble condition and the control point, and drops 24V power to reset the Class A latch.
The conversion of a BMUX to 4100U/4100ES system will require the power pre-amplifiers
located in the adjacent SCC to be removed or disabled as part of the upgrade. When Class A audio
risers are upgraded, refer to Figure 9 for wiring details to connect the riser NAC, the monitor point
and the control point to the Class A audio monitor board. The monitor and control points will be
provided by Zone Modules (4100-5005) and Auxiliary Relay Modules (4100-3202, -3204, -3206)
respectively in the 4100U/4100ES.
Continued on next page
firealarmresources.com
Summary of Contents for 4100-6065
Page 19: ...firealarmresources com...
