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Tektronix 453 User Manual

Tektronix 453
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Circuit
Description-Type
453/R453
r-------------------
Unblanking gate
from
Z Axis
,,,,,.
Amplifier
Control-Grid
Rectifier
0940
F937
TRACE
ROTATION
Unregulated
15-volts from
+ 12-Volt
Rectifier,
Power Supply
Circuit
.....,
____
_..,.
High-Voltage
Oscillator
0930
High-Voltage
Rectifier
V952,
V962
0952
ASTIG
To
Z Axis
Amplifier
z
AXIS
INPUT
Fig.
3-16.
CRT
Circuit detailed block diagram.
The
collector
current
of
0930
increases
and
a
voltage
is
developed
across
the
collector
winding
of
T930. This
pro-
duces
a
corresponding
voltage
increase
in
the
feedback
wind-
ing
of
T930 which
is
connected
to
the
base
of
0930,
and
it
conducts
even
harder.
While
0930
is
on, its
base
current
exceeds
the
current
through
R925
and
C913
charges
nega-
tively. Eventually
the
rate
of
collector
current
increase
in
0930
becomes
less
than
that
required
to
maintain
the volt-
age
across
the
collector
winding
and
the
output
voltage
drops.
This turns off
0930
by
way
of
the
feedback
voltage
to
the
base.
The
voltage
waveform
at
the
collector
of
0930
is
a sine
wave
at
the
resonant
frequency
of
T930.
0930
re-
mains off until a little less
than
one
cycle
later
when
C913
discharges
sufficiently
to
raise
the
voltage
at
the
base
of
0930
positive
enough
to
bias
0930
into
conduction
again.
The cycle
repeats
at
a
frequency
of
40 to
50
kilohertz. The
amplitude
of
sustained
oscillation
depends
upon
the
average
current
delivered
to
the
base
of
0930.
Fuse F937
protects
the
+ 12-volt
Supply
if
the High-Volt-
age
Oscillator
stage
is
shorted.
C937
and
L937
prevent
the
current
changes
at
the
collector
of
0930
from
affecting
the + 12-volt
regulator
circuit.
High-Voltage Regulator
Feedback
from the
secondary
of
T930
is
connected
to the
base
of
0914
through
the
voltage
divider
network R901-
R910. This
sample
of
the
output
voltage
is
compared
to
the
-12-volt
level
at
the
emitter
of
0914.
It
is
then
amplified
by
0914
and
0913
and
applied
to the
base
of
0923.
Amplitude
of
the oscillations
at
the
collector
of
0930
3-24
is
determined
by
the
average
DC level
at
the
emitter
of
0923.
Regulation
takes
place
as
follows:
If
the
output
voltage
at
the
-1950
V test
point
starts
to
go
positive (less negative),
a
sample
of
this positive-going
voltage
is
applied
to
the
base
of
0914.
0914
is
forward
biased
and
it,
in
turn,
forward
biases
0913
to
increase
the
conduction
of
0923.
An in-
crease
in
current
through
0923
raises
the
average
voltage
level
of
its
emitter
which
is
connected
to
the
base
of
0930
through
the
feedback
winding
of
T930. A
more
positive
level
at
the
base
of
0930
increases
the
collector
current
to
produce
a
larger
induced
voltage
in
the
secondary
of
T930.
This
increased
voltage
appears
as
a
more
negative
voltage
at
the
-1950
V test
point
to
correct
the
original
positive-
going
change.
By
sampling
the
output
from
the
cathode
supply
in
this
manner,
the
total
output
of
the
high-voltage
supply
is
held
constant.
Output
voltage
level
of
the
high-voltage
supply
is
con-
trolled by the High
Voltage
adjustment,
R900,
in
the
base
circuit
of
0914.
This
adjustment
sets
the
conduction
level
of
0914
which controls
the
quiescent
conduction
of
0913,
0923
and
0930
similar to
the
manner
just
described
for a
change
in
output
voltage.
High Voltage Rectifiers and Output
Below
s~rial
number
44~60,
the
high-voltage
transformer,
T930 has five
output
windings. Two
of
these
windings
pro-
vide
filament
voltage
for
the
rectifier
tubes,
V952
and
V962.
Serial
number
44360
and
above,
rectifier
tubes
V952
and
®

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Tektronix 453 Specifications

General IconGeneral
BrandTektronix
Model453
CategoryTest Equipment
LanguageEnglish

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