Section III. TECHNICAL PRINCIPLES OF OPERATION

TM 11-5820-765-34

Section III.

T E C H N I C A L PRINCIPLES OF OPERATION

1-10.

BLOCK

DIAGRAM

ANALYSIS

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-

cy interference (RFI) filter to the circuit breaker.

With the circuit breaker closed (POWER ON),

input power flows to the power transformer,

which feeds the fan motor, circuit card

assembly, and all of the power supply's circuits.

Output: The transformer applies power

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-

vides automatic, continuous voltage regulation.

A filter network purifies the dc signal; the

regulated positive dc output flows through

the

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

change

the

voltage.

overvoltage

circuit,

activated

when

needed,

applies a short-circuit load to the output ter-

minals, opening the circuit breaker. This pro-

tects the power supply and the equipment being

powered.

The

output

voltage

meter

(voltmeter)

monitors

output voltage, which passes again through the

RFI filter before reaching the dc output terminal.

1-5