R617,
R618, between
the
-150
-volt bus and
ground.
R617,
labeled
-150 ADJ.,
determines
the
percentage of
the
total
voltage
that
appears
at
the
grid
of
V607A
and
thus
determines
the
total
voltage
across
the
divider.
The
voltage
difference
between
the two
grids
of
V607
appears as
an
amplified
error
signal
at
the
plate
of V607B.
The
amplified
error
signal
is
de coupled
to
the
grid of
the
series
-
regulator
tube,
V610.
This
dc-coupled
error
signal
controls
the
plate
resistance
of
the
series
regulator
tube,
changing
it
in
the
right
direction to
compensate
for
any
change
in
output
voltage. C613
increases
the
ac
gain
of
the
feedback
loop
to
reduce the
ripple.
The
screen
of
V607B
has
a
small
amount
of
the
ripple
that
exists
ahead
of
the
series
regulator
tube
connected
to
it
through R605.
The
phase
of
this
ripple
is
such
as
to
reduce
the
ripple
of
the
-150-volt bus.
This
circuit
also
improves
the
regulation
in
the
presence
of
line-voltage
variation.
R620
bypasses
the
series
tube
to
reduce
the
amount
of
load
current
through
it.
+
100-Voft Supply
The
-150-volt
supply
serves
as
reference
voltage
for
the
+
100-volt
supply.
The
voltage
at
the
tap
on
the
voltage
divider,
R639, R640,
is
applied
to
the
grid
of
V631.
The
error
signal
is
amplified
in
V631
and
applied
to
the
grid
of
V635B,
the
series-regulator
tube.
R633,
at
the
screen
of
V631,
reduces
ripple
and
improves
the regulation of
the
supply.
C636
increases
the
ac
gain
of
the
feedback
loop.
+ 300-Volt
Supply
Rectified voltage
from
terminals
8
and
9
of
the
power
transformer
is
added
to
the
voltage
supplying
the
+
100-volt
regulator
to
provide about
400
volts
for
the
+
300-volt
regulator
and
other points
in
the
instrument
which
do not
ned
a
regulated voltage.
The
+
300-volt
circuit
is similar
in
operation
to
the
+
100-volt
regulator.
CRT
CIRCUIT
High-Voltage
Supply
Accelerating
voltage
for
the
cathode-ray tube
is
obtained
by rectifying
a
60-kc
voltage
pro
duced
by
a
vacuum-tube
oscillator.
V705
is
the
oscillator
tube
with
the
primary
of
T701
serving
as
a
tapped
inductor.
Rectifier
V720
supplies
-1675
volts
to
the
ert cathode
andV721
supplies
+2325
volts
to
the
post-acceleration
helix
to
provide
a
total
acceleration
voltage
of
4000
volts.
High-Voltage Regulator
A
divider
from
the
ert cathode
to
the
+300-
volt bus
applies
a
sample
of
the
negative
accelerating
voltage
to
the
grid
of
V710B.
R741
varies
the
voltage
at
the
tap
to
adjust
the
high
voltage.
The
-150-volt
supply, con
nected
to
the
cathode
of
V710B,
serves as
a
reference
voltage.
The
amplified
error
signal
at
the
plate
of
V710B
is
applied
to
the
grid
of
the
shunt
regulator
tube,
V710A.
The
shunt
regulator
tube
determines
the
screen
voltage
of
the
oscillator tube
and
thus
controls
the
oscillator
output
voltage.
If,
for
example,
the output
voltage becomes
too
high,
the
regulator reduces
the
voltage
on the
screen
of
the
oscillator
tube.
The
output
voltage
of
the
oscillator
decreases
and
the
output
voltage
is
corrected.
U
nblanking
The
ert
control-grid
voltage
is
produced
by
a
winding
and
rectifier,
V724,
similar
to
the
cathode
supply
but insulated
from
it.
The
positive
end
of
the
control-grid supply
is
connected
to
the
unblanking
cathode
follower.
When
the
unblanking
pulse
is
produced
at
the
cathode
of
the
unblanking
cathode
follower,
it
drives
the
whole
grid-voltage
supply
with
it
so
that
the
pulse
appears at
the
ert
grid.
Since
this
is
a
de
connection,
the
unblanking
pulse
can
have
any duration
with
no
change
in
grid
voltage.
The
INTENSITY control,
R731,
varies
the
bias
on
the
grid
to
determine
trace
brightness.
CRT Geometry
Control
The
second-anode
voltage
required
for
best
linearity
at
the
extremes
of
deflection
may
vary
somewhat
between
tubes.
R753,
labeled
GEOM.
ADJ.
on
the
chassis, permits
this
voltage to
be adjusted.
3-6
Circuit
Description
- Type 515/515A
AA