EasyManuals Logo

Tektronix 7613 User Manual

Tektronix 7613
224 pages
To Next Page IconTo Next Page
To Next Page IconTo Next Page
To Previous Page IconTo Previous Page
To Previous Page IconTo Previous Page
Page #53 background imageLoading...
Page #53 background image
Circuit
Description—7613/R7613
Service
are
forward
biased
by
this
positive
change,
which
in
turn
increases
the
conduction
of
01214.
This
results
in
a
greater
bias
current
delivered
to
the
bases
of
01216-01218
through
Q1214.
Now,
the
bases
of
both
01216
and
Q1218
are
biased
closer
to
their
conduction
level
so
the
feedback
voltage
induced
into
their
base-feedback
windings
produces
a
larger
collector
current.
This
results
in
a
larger
induced
voltage
in
the
secondary
of
T1225
to
produce
a
more
negative
level
at
the
—1475
V
test
point
to
correct
the
original
error.
In
a
similar
manner,
the
circuit
compensates
for
output
changes
in
a
negative
direction.
Since
the
amplitude
of
the
voltage
induced
into
the
secondary
of
T1225
also
determines
the
output
level
of
the
positive
High-Voltage
Supply
and
the
Control-Grid
Supply,
the
total
high-voltage
output
is
regulated
by
sampling
the
output
of
the
negative
High-Voltage
Supply.
High-Voltage
Supplies
High-voltage
transformer
11225
has
two
output
windings.
One
winding
provides
filament
voltage
for
the
cathode-ray
tube.
The
other
winding
provides
the
negative
and
positive
accelerating
potential
for
the
CRT
and
the
bias
voltage
for
the
control
grid.
All
of
these
voltages
are
regulated
by
the
High-Voltage
Regulator
stage
to
maintain
a
constant
output
voltage
as
previously
described.
Positive
accelerating
potential
for
the
CRT
anode
is
sup-
plied
by
the
voltage
doubler.
The
applied voltage
-from
the
secondary
of
T1225
is
about
3.5
kilovolts
peak-to-peak.
This
results
in
an
output
voltage
of
about
+7
kilovolts
at
the
CRT
anode.
The
negative
accelerating
potential
for
the
CRT
cathode
is
also
obtained
from
this
same
secondary
winding.
Half-wave
rectifier
CR1232
provides
an
output
voltage
of
about
—1.475
kilovolts
which
is
connected
to
the
CRT
cath-
ode
through
R1234.
The
cathode
and
filament
are
connected
together
through
R1275
to
prevent
cathode-to-filament
breakdown
due
to
a
large
difference
in
potential
between
these
CRT
elements.
A
sample
of
the
negative
accelerating
voltage
is
connected
to
the
High-Voltage
Regulator
to
main-
tain
a
regulated
high-voltage
output.
The
network
consisting
of
diodes
CR1269-CR
1268-CR
1270-CR
1264-VR1264
provides
the
negative
voltage
for
the
control
grid
of
the
CRT.
Output
level
of
this
supply
is
set
by
CRT
Grid
Bias
adjustment
R1261.
Approximately
600
volts
peak-to-peak
from
the
secondary
of
11225
is
connected
to
the
Control-Grid
Supply
through
C1266
and
R1266.
Diodes
CR1268
and
CR1264
clip
this
signal
to
determine
the
operating
level
at
the
control
grid.
CR1268
limits
the
negative
excursion
of
the
signal;
quiescently
when
the
CRT
is
blanked,
the
anode
of
CR1268
is
set
at
about
+15
volts
by
the
Z-Axis
Amplifier
stage.
The
positive
clipping
level
at
the
cathode
of
CR1264
is
set
by
CRT
Grid
Bias
adjustment
R1261.
R1261
is
adjusted
to
bias
the
control
grid
of
the
CRT
just
3-26
enough
negative
so
the
trace
is
blanked
between
sweeps.
Under
normal
conditions,
this
biases
the
control
grid
about
80
volts
more
negative
than
the
cathode.
The
negative
level
at
the
CRT
cathode
is
connected
to
the
cathode
of
CR1270.
This
level
is
held
constant
by
the
High-Voltage
Regulator
as
described
previously.
The
clipped
voltage
developed
by
diodes
CR1264
and
CR
1268
is
peak
to
peak
rectified
by
diodes
CR1269
and
CR1270
and
super-imposed
on
this
negative
voltage
to
result
in
a
level
at
the
grid
of
the
CRT
which
is
more
negative
than
the
CRT
cathode
level.
C1269
acts
as
a
filter
to
provide
a
constant
voltage
output
level.
The
unblanking
gate
level
developed
by
the
Z-Axis
Amplifier
stage
is
applied
to
the
anode
of
CR1268
through
R1157.
The
fast
rising
and
falling
portions
of
this
signal
are
coupled
directly
to
the
output
through
C1269.
The
overall
effect
of
the
unblanking
gate
is
to
further
clip
the
negative
excursions
thereby
reducing
the
voltage
difference
between
grid
and
cathode
of
the
CRT.
This
allows
the
cathode
current
of
the
CRT
to
pass
to
the
anode
so
the
display
can
be
viewed.
CRT
Control
Circuits
The
focus
of
the
display
is
determined
by
the
FOCUS
control
R1045.
This
control
and
the
Auto
Focus
amplifier
maintains
a
well-defined
display
for
fast
changes
in
the
intensity
of
the
display.
The
network
consisting
of
CR1255,
CR1254, CR1253,
CR1258,
and
VR1258
provide
the
negative
voltage
for
the
focus
grid
of
the
CRT.
Approximately
600
volts
peak-to-peak
from
the
secondary
of
11225
is
connected
to
the
focus
grid
supply
through
C1257
and
R1257.
The
positive
clipping
level
at
the
anode
of
CR1258
is
set
by
the
FOCUS
control
setting.
This
determines
the
operating
level
at
the
focus
grid.
Under
normal
operating
conditions
the
voltage
applied
to
the
focus
grid
is
more
positive
(less
negative) than
the
contro!
grid
or
the
cathode
of
the
CRT.
The
signal
developed
by
the
Auto
Focus
amplifier
is
coupled
to
the
focus
grid
by
C1254.
When
there
is
a
sudden
change
in
intensity
levels
the
focus
grid
level
will
change
to
maintain
a
well-defined
display.
Astigmatism
adjustment
R1193,
which
is
used
in
conjunction
with
the
FOCUS
control
to
obtain
a
well-
defined
display,
varies
the
positive
level
on the
astigmatism
grid.
Geometry
adjustment
R1184
varies
the
positive
level
on
the
horizontal
deflection-plate
shield
to
contro!
the
overall
geometry
of
the
display.
Two
adjustments
control
the
trace
alignment
by
varying
the
magnetic
fields
induced
by
coils
around
the
CRT.
Y-Axis
Alignment
R1190
controls
the
current
through
1098,
which
affects
the
CRT
beam
after
vertical
deflec-
tion,
but
before
horizontal
deflection.
Therefore,
it
affects
only
the
vertical
(Y)
components
of
the
display.
Beam
Rotation
adjustment
R1181
controls
the
current
through
L1099
and
affects
both
the
vertical
and
horizontal
rotation
of
the
display.
7613

Table of Contents

Questions and Answers:

Question and Answer IconNeed help?

Do you have a question about the Tektronix 7613 and is the answer not in the manual?

Tektronix 7613 Specifications

General IconGeneral
BrandTektronix
Model7613
CategoryTest Equipment
LanguageEnglish

Related product manuals