T E C H N I C A L PRINCIPLES OF OPERATION
The block diagram describes the power sup-
ply's major electronic components and circuits.
The power supply requires an input of 115
volts ac or 230 volts ac for operation, and has an
output of 27-29 volts dc.
Input power: Applied through a radio frequen-
With the circuit breaker closed (POWER ON),
which feeds the fan motor, circuit card
assembly, and all of the power supply's circuits.
through a reactor to a full-wave bridge rectifier,
which converts the input flow to dc. A silicon
controlled rectifier regulates the dc output; con-
trol circuitry in the circuit card assembly pro-
A filter network purifies the dc signal; the
regulated positive dc output flows through
output current meter (ammeter) and is shunt to
the dc output terminal.
A voltage adjust circuit permits manual adjust-
ment of the output voltage; controls in the cir-
cuit card assembly sense the adjustment and
applies a short-circuit load to the output ter-
minals, opening the circuit breaker. This pro-
tects the power supply and the equipment being
output voltage, which passes again through the
RFI filter before reaching the dc output terminal.