Power Supply; Figure 2-6 Ble*/* Power Supply - Motorola BLE Series Installation And Operation Manual

2-6 Overview

Power Supply

The BLE*/* power supply is a separate circuit board mounted to the underside of the amplifier
module and is capable of 60 Vac or 90 Vac powering. The power supply provides a regulated
24 Vdc output over an ac input between 38 Vrms and 90 Vrms with a line frequency from 50 Hz
through 60 Hz. Potentiometer R25 adjusts the output voltage to 24 Vdc, however, this is set at
the factory and field adjustment is not recommended.
Figure 2-6 illustrates the components on the power supply:
Figure 2-6
BLE*/* power supply
P2-3
P2-2
D1
P2-1
The power supply also contains a two-position
38 Vac or 55 Vac. The BLE*/* is shipped with the selector in the
standard configuration. The selector should be switched to the
system. This sets the start-up voltage at 55 Vac. Because this is only 5 V below 60 Vac, it is not
practical in a 60 Vac system. There is no damage to the amplifier if the selector is not changed
from the standard setting. However, changing the selector ensures that the dc supply does
LO
not turn on until the proper input voltage, 38 Vac or 55 Vac, is reached. This prevents excessive
loading of the system power supply during turn-on after a system shutdown.
You must remove the power supply cover to access the selector illustrated in Figure 2-6.
Section 3, "Amplifier Setup" explains changing the setting of this selector to meet system
requirements.
The power supply includes a heavy-duty gas discharge tube that you can replace with the
optional fast-transfer electronic-crowbar (FTEC) surge protector. The FTEC is a crowbar circuit
that fires at approximately 245 V and presents a short circuit to the line during periods of
overvoltage. After the ac input voltage returns to normal, the FTEC resumes its open state.
The factory-installed 20-ampere fuse, illustrated in Figure 2-8, provides power-passing to
additional line extenders.
BLE*/* Installation and Operation Manual
L2
C26 C2
L8
C25
P1
1
X1 X2
SURGE PROTECTOR
Surge protector
or FTEC
LO
R25
C7
C6 C5
C1
C22
C12
R25 C11 C10 J1
LO
HI
U4
E1
E2
U3
Q1 U2
L3
C17
LO/HI
selector
/ selector that sets the start-up voltage for
HI
position which is the
LO
position only for a 90 Vac
HI
L1
C3
D5
T1
U1