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Tektronix 585 - Page 44

Tektronix 585
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Circuit
Description
—
Type
585
Fig.
4-11.
Waveform
ladder
diagram
of
the
Delay-Time
Multiplier
circuit
operation.
operation.
The
power
supply
will
maintain
regulation
over
line
voltage
ranges
of
105
to
125
volts,
or
210
to
250
volts,
rms,
50-60
cycles,
when
the
line
voltage
has
less
than
about
3
to
5%
distortion
of
the
waveform
peaks.
All
Type
585
power
transformers,
after
serial
number
310
are
provided
with
two
6%
Boost-Buck
windings
to
permit
primary
turns
adjustment
to
suit
slightly
different
line
voltages
from
those
just
mentioned.
Refer
to
Figures
2-1
and
2-2
for
additional
details.
—
1
50-Volt
Supply
Reference
voltage
for
the
—
1
50-volt
supply
is
furnished
by
a
gas
diode
voltage-reference
tube
V609.
This
tube,
which
has
a
constant
voltage
drop,
establishes
a
fixed
potential
of
about
—
87
volts
at
the
grid
of
V624A,
one-
half
of
a
difference
amplifier.
The
grid
voltage
for
the
other
half
of
the
difference
amplifier,
V624B,
is
obtained
from
a
divider
consisting
of
R615,
R616,
and
R617.
The
—
150
ADJ.
control
R616
determines
the
percentage
of
total
output
voltage
that
appears
at
the
grid
of
V624B
and
thus
determines
the
total
voltage
across
the
divider.
This
control
is
adjusted
so
that
the
output
volta
g
e
is
—
150
volts,
±
2%.
If
line-voltage
or
load
fluctuations
tend
to
change
the
output
voltage,
an
error
signal
is
produced
between
the
two
grids
of
the
difference
amplifier.
The
error
signal
is
amplified
in
V624B
and
V634
and
applied
to
the
grids
of
the
series
tubes
V627,
V637
and
V
647.
The
resulting
change
in
voltage
at
the
plates
of
the
series
tubes
corrects
the
—
150-volt
bus
back
to
its
original
value.
Capacitors
C617
and
C628
improve
the
ac
gain
of
the
feedback
loop
to
increase
the
rate
of
response
of
the
regulator
circuit
to
sudden
changes
in
output
voltage
and
to
reduce
ripple.
A
small
amount
of
unregulated
bus
ripple
is
coupled
to
the
screen
of
V634
through
R637.
The
phase
of
the
amplified
ripple
voltage
at
the
plate
of
V634
is
such
as
to
cancel
most
of
the
ripple
on
the
—
150-volt
bus.
+
100-Volt
Supply
Reference
for
the
+
100-volt
supply
is
a
voltage
located
at
a
point
near
ground
potential
obtained
from
a
divider
R650-R651.
V664
essentially
compares
the
reference
voltage
to
ground.
Any
voltage
change
at
the
+
1
00-volt
output
is
amplified
and
inverted
in
polarity
by
V664
and
applied
to
the
grid
of
series
regulator
V677A
correcting
the
output
voltage.
Capacitor
C650
improves
the
ac
gain
of
this
circuit
and
helps
to
eliminate
ripple.
A
small
sample
of
the
unregulated
bus
ripple
appears
at
the
screen
of
V664
through
R667.
This
produces
a
ripple
component
at
the
grid
of
series
regulator
V
677
A
.
that
is
opposite
in
polarity
to
the
ripple
at
the
plate.
This
tends
to
cancel
the
ripple
at
the
cathode
and
hence
on
the
+1
00-
volt
bus.
This
same
circuit
also
improves
the
regulation
in
the
presence
of
line-voltage
variations.
+
225-Volt
Supply
The
+
225-volt
supply
source
is
the
secondary
windings
between
terminals
5
and
7
and
terminals
10
and
14
of
T601,
part
of
a
two-voltage
supply.
Diodes
D702
A
and
B
serve
as
full-wave
rectifiers
for
the
4-225-volt
supply,
with
their
center
lead
connected
to
the
+1
80-volt
unregulated
supply.
Voltage
from
the
full-wave
rectifier
system
is
added
to
the
+
1
80-volt
unregulated
lead
to
provide
sufficient
voltage
for
the
4-325-volt
unregulated
lead
and
the
4-225-volt
regulated
supply.
Reference
for
the
+
225-volt
supply
is
a
voltage
located
at
a
point
near
ground
obtained
from
the
divider
R680-R681.
V684A
essentially
compares
the
reference
voltage
to
ground.
Any
voltage
changes
at
the
+
225-volt
output
produces
an
error
voltage
between
the
grids
of
the
difference
amplifier
V684.
The
error
signal
is
amplified
in
both
V684
and
V694,
and
coupled
to
the
grids
of
series
regulators
V677B
and
V737A.
The
voltage
change
at
the
cathode
of
V677B
and
V737A,
due
to
the
regulator
action,
is
opposite
in
polarity
to
the
original
error
signal
keeping
the
output
voltage
con
stant.
The
unregulated
output
of
about
+
325
volts
is
used
by
the
oscillator
of
the
crt
high-voltage
supply.
It
is
un
necessary
to
regulate
this
voltage
as
the
crt
supply
has
its
own
regulator
circuit.
+
350-Volt
Supply
The
+
350-volt
supply
source
is
at
the
common
connection
between
Diodes
D732
A
and
B.
These
diodes
are
part
of
a
full-wave
bridge
rectifier
system.
4-14

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