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INSTALLATION GUIDE
SOUNDER CIRCUIT CONTROL UNIT – 24V DC
SCB-241 / SCB-243 / SCB-245
General
This sounder control unit is for use on most Fire Alarm system sounder circuits operating on
24v dc. The unit includes a n output for sounders and a 27.6V DC charger for use with Sealed
Lead Acid Batteries up to 12Ah. The total sounder load connected to the unit should not
exceed 3 Amp.
The unit should be fitted in an upright position on a solid surface using the fixing holes
provided.
Supply
Supply to the unit should be 240V ac 50Hz and an earth should be fed to the unit via a 5amp fused outlet, fitted adjacent to the unit. The mains supply in the enclosure should be wired
into the fused terminal block next to the PCB. The unit should be earthed.
Operation
With mains 240vAC connected the unit will charge batteries when fitted correctly and will
give an output of 24v DC +/-10% to supply sounders and/or strobes etc when required by the
Fire Alarm Control Panel to do so.
All sounders and strobe units etc must be polarised as is normal with fire alarm sounder
circuits.
This unit also has a fault-monitoring relay on the PCB. The relay is energised when the unit is
operating under normal (fault free) conditions and gives a set of voltage free contacts at the
‘Fault Relay Output’. The relay will operate in tandem with the fault LED. These contacts
can be used to signal faults to a remote monitoring system or to control a remote indicator or
small buzzer unit if required).
The sounders must be wired to the connector block and the resistor normally supplied with
the Fire Alarm Control Panel must be fitted at the end of the sounder wiring in the last
sounder unit. Polarity of the sounder wiring must be observed or a fault will be given at the
Fire Alarm Control Panel
Connections
For connections refer to additional sheets with these instructions.
Lid Indicators
Green = Supply Healthy Amber = Fault
When the Green light only is illuminated, the unit is operating normally with supply to the
load and the batteries (when fitted) are receiving charge current. When the Amber light is
illuminated at the same time as the Green light there is a fault on either or both of the output
supply and the charge supply. If the Green light is NOT illuminated, the mains supply is not
present.
Power Supply Fuses
F.1 Output = SCB-241 1amp, SCB-243 3amp, SCB-245 5amp. (20mm x 5mm)
F.2 Battery = SCB-241 1amp, SCB-243 3amp, SCB-245 5amp. (20mm x 5mm)
PCB Indicators
Amber LED adj battery connection when lit indicates blown battery fuse or mains fail
Amber LED adj outputs connection when lit indicates output fuse blown.
Red LED “remote” when lit indicates input from Fire Alarm Panel or other trigger
24v dc input.
User Guide – Ref. Doc – 040b
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