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3.6.
PCB-POWER CIRCUIT
This power circuit is constructed as a Series-Regulator
and
outputed
+100 V, +12 V
and
+6.3 V
de power source.
3.6.l
Positive
100 V
de Regulator
The input ac line voltage is applied to the primary
windings
of
the power transformer,
T991
through
connectors
PE, PF,
power switch
5991
and connectors
PJ, PK, PL.
A
Jumper
plug, PJ
must be placed in
the
appropriate
position depending
on
the input ac line voltage.
The +100 V de regulator is supplied with ac power
from T991, is rectified by diode
D901,
filtered by
C905, and applied to the collector of power output
transistors,
Q991
and
Q992
which is connected
in
pararel.
The series regulator
derives its name from the
control
element it uses.
The
output
voltage is regulated
by modulating
a series element, usually a transistor,
that acts as a variable resistor.
Changes in input
voltage result in a change in the equivalent resistance
of the series element.
The product of this resistance
and the load current create a changing differential
voltage that compensates for a changing input voltage.
The comparator transistor
Q903
compares the attenuated
regulator output voltage, applied to its base through
VR901
to the reference
zener
voltage of the
0905,
and
creating an error signal voltage.
This error signal
voltage is applied to the base of
Q901,
maintaining
3-20
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