Instruction manual

9-3
Section 9-2 - Single Circuit Mother Board (SCMB)
Wheelock, Inc. Part Number 108974
The Single Circuit Mother Board provides all signal handling capabilities between itself and the amplifier
modules, terminal blocks for output wiring, and connectors for handling signals from the digital voice
module.
The Single Circuit Mother Board is illustrated in Figure 9-2 on Page 9-5.
A single amplifier module is connected to the SCMB.
A single channel from the Digital Voice Module (MDX-2) is connected to the SCMB. The digital voice
module is mounted on the power supply cover and wired to the Mother Board. The digital voice module
channel will play through the amplifier module installed.
The microphone input is located in the lower right corner of the board and is used for live voice
announcements.
Form C contacts are available for remote monitoring of Alarm Status and Trouble Status. Also remote
trouble power is available at 24VDC, 0.100 Amps, that is non-supervised.
Single Circuit Mother Board supervises the Digital Voice Module (MDX-2), Power Supply, and the
amplifier module (SAA-40S, SAA-80S/SE, or SALL-15S) for proper operation. The microphone is
supervised for connection.
The channel play contacts from the digital voice module (MDX-2) are monitored to determine their status
(e.g. active or inactive). If the channel play contact is inactive, the control module routes a supervision
tone to the amplifier circuit module and monitors the amplifier for functionality. If the channel playing
contact is active, the control module routes the audio from that MDX-2 line output to the amplifier circuit
module. Wiring used to monitor the channel play contacts and to route the line output from the Digital
Voice Module is supervised for open and short circuit conditions.
The Power Supply module is supervised for two conditions: low AC input power, and low battery voltage.
The wiring between the controller module and the battery charger is supervised for open and short circuit
conditions.
The amplifier module is supervised for two failure conditions: field wiring trouble conditions and amplifier
audio output trouble conditions. The SCMB only supervises the audio output during standby conditions.
When either a message is playing from the Digital Voice Module or a live announcement is being made
from the microphone, the field wiring and audio output are not supervised.
The strobe NAC circuit can be used with standard non-synchronized strobes or the circuit can be place in
the SYNC mode for synchronizing Wheelock, Inc. synchronized strobes. Synchronization is accomplished
by turning “ON” DIP Switch SW5, Position 3 (SYNC) on the SAMB.
The strobe NAC circuit on the amplifier module is also supervised in the standby mode for field wiring
trouble conditions.
If at any time a trouble condition is detected, the SCMB will energize the internal audible, the external
trouble audible circuit, and transfer the Form C trouble contact to the trouble position, turn “OFF” the
NORMAL LED, and turn “ON” the TROUBLE LED.
There are two fuses on the Mother Board. F1 is the fuse for the external trouble audible circuit, and F2 is
the fuse for the Remote Microphone Station power. Both fuses are rated at 0.5A. See Figure 9-2 on
Page 9-5 for fuse location.
Fuse Rating
F1 0.5A
F2 0.5A