Noby-448 Installation & Programming Instructions (Rev.5) Page 3 of 12
POWER SUPPLY
The PSU comprises two high-efficiency regulators providing voltage rails of 27.3v and 13.6v (nominal 24v and 12v
respectively), with a combined continuous current rating of 2.0A, and a 20 minute rating of 2.5A. The PSU is
designed to meet the internal standby power requirements of the Noby-448 and also to charge and maintain the
SLA standby battery in optimum condition. The battery standby time is dependant upon the overall system current
drawn, including any ancillary equipment connected to the Aux 24v and Aux 12v terminals. Also it is strongly
recommended that the continuous system standby current does not exceed 1.5A, because some ‘reserve’ PSU
current may at times be required to rapidly re-charge the battery (e.g. after an alarm condition or prolonged period
of mains loss).
The Noby-448 enclosure can accommodate two 12v/7Ahr SLAs connected in series. The PSU is capable of
handling batteries up to 12Ahr, but these larger batteries must of course be housed in a separate enclosure. Care
must be taken when planning an installation that there is sufficient battery capacity to meet the relevant standards
regarding battery standby times.
Always ensure that the maximum current drawn in alarm does not exceed the 3.0A battery fuse limit (F7).
The PSU is monitored for :
i) Mains Absence Power LED extinguishes when mains absent for more than 90
seconds and flashes once mains restored. Mains absence is
accompanied by an intermittent warning bleep every 16s
(mutable).
ii) Low Voltage < 21v PSU Fault LED continuously lit whilst voltage < 21v and flashes
when voltage is restored to > 23v
iv) Battery Capacity Test PSU Fault LED flashes
iii) Fuse F7 (Battery/Low Volts) PSU Fault LED flashes
v) Fuse F1 (Remote/Aux 12v) PSU Fault LED flashes
vi) Fuse F2 (Aux-24v) PSU Fault LED flashes
Note 1: PSU faults are accompanied by a fault tone signified by 4 rapid pips every 4 seconds.
Note 2: The Battery Capacity Test is performed immediately after a System Reset and thereafter at 12 hour
intervals.
REMOTE KEYPAD BUS
Up to three external Noby-448RKP remote keypads can be connected to the remote serial bus.
Ensure correct connectivity A to A and B to B.
Each Noby-448RKP must be set to a unique dip-switch address in the range 2 to 4 (the factory setting is address
2). Note that address 1 is reserved for the internal lid mounted keypad on the Noby-448.
Take care when installing a 3
rd
or 4
th
keypad to adjust the address switch to 3 or 4.
Note that the system is tolerant of address gaps i.e. it is OK to have addresses 1,2 and 4, but address conflicts
will give rise to spurious keystroke entry.
The bus address configuration is registered at first power-up and again every time the panel is reset.
Any loss of communication is indicated by a continuously lit CPU Fault LED, together with an audible fault warning
from any remaining functional keypads. There is also a 'backup' piezo sounder on the main PCB to draw attention
to a bus fault. In the event of complete remote bus failure the panel will fail safe and continue to operate as a fire
detection system, albeit without the means to silence it. The fuse F1 supplying the Remote Bus is monitored and
will generate a simultaneous PSU Fault and CPU Fault condition if it should blow.
The maximum cable length is largely determined by the type of cable employed and the installation environment.
The remote keypads can be wired and distributed along the cable in any configuration provided the total cable
length connected does not exceed 500m.
Important: the main precaution is to minimise the volt drop along the 12v and 0v supply cores by using thicker wire
or doubling up the spare cores. In normal standby, with only the Power LED lit, the terminal voltage at each remote
should be 12v or higher (as compared to approx.13.6v at the panel terminals). When troubleshooting, a good rule
of thumb is that the voltage at the remote keypads must not drop below 10v at maximum current draw during the 3
second reset period - i.e. this is the maximum current draw when all LEDs are lit.
Failure to heed this warning may give rise to intermittent and/or unreliable remote keypad operation.
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