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Tektronix 7613 User Manual

Tektronix 7613
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stage
through
C2155.
Pin
13
of
U2155D
goes
LO
ta
enable
the
Time-Slot
Counter
and
Timer
stages
for
the
next
time-slot
pulse.
At
the
same
time,
the
negative-going
edge
produced
at
U2155D
switches
output
states
which
is
connected
to
pin
3
of
U2155D.
This
results
in
a
negative-
going
Word
Trigger
output
at
pin
4
of
U2155B
to
advance
the
Channel
Counter
to
the
next
word.
When
the
next
Trigger
pulse
is
received
at
pin
15,
the
Time-Slot
Counter
returns
to
the
normal
sequence
of
operation
and
produces
an
output
on
the
time-slot
1
line.
Channel
Counter
The
Channel
Counter,
made
up
of
integrated
circuit
U2250
is
a
binary
counter
which
produces
the
Channel
Address
code
for
the
Column
and
Row
Decoder
stages
and
the
Format
Generator
stage.
This
code
instructs
these
stages
to
sequentially
select
and
display
the
six
channels
of
data
from
the
plug-in
units.
The
input
channel
which
is
displayed
with
each
combination
of
the
Channel
Address
code
is
given
in
the
discussion
of
the
applicable
stages.
Single-Shot
Lockout
Q2108,
Q2117,
and
U2120
makes
up
the
Single-Shot
Lockout
stage.
This
stage
allows
a
single
readout
frame
(Six
complete
words)
to
be
displayed
on
the
CRT,
after
which
the
Readout
System
is
locked
out
so
further
readout
displays
are
not
presented
until
the
circuit
is
reset.
U2120C
and
U2120B
are
connected
to
form
a
bistable
flip-flop.
For
normal
operation,
pin
3
of
U2120
is
pulled
HI!
through
R2108.
This
activates
U2120C
to
result
in
a
LO
output
level
at
pin
10.
This
level
enables
the
Timer
stage
so
it
can
operate
in
the
free-running
manner
as
described
previously.
The
LO
at
pin
10
of
U2120C
is
also
applied
to
pin
5
of
U2120B.
Since
pin
6
of
U2120A
is
LO,
U2120B
is
disabled
and
its
output
goes
HI.
The
output
of
this
stage
remains-LO
to
allow
U2126
to
operate
in
the
free-running
mode
until
a
LO
is
received
at
pin
8
of
U2120C.
When
this
occurs,
the
output
level
at
pin
10
of
U2120C
does
not
change
immediately.
However,
the
Readout
System
is
now
enabled
as
far
as
the
single-shot
lockout
function
is
concerned.
If
the
Channel
Counter
has
not
completed
word
six
(Channel
2
of
the
Horizontal
unit),
the
Readout
System
continues
to
operate
in
the
normal
manner.
However,
when
word
six
is
completed,
a
positive-
going
End-of-Frame
pulse
is
produced
at
pin
9
of
U2120B
as
the
Channel
Counter
shifts
to
the
code
necessary
to
display
word
one.
This
pulse
is
coupled
to
pin
3
of
U2120A
and
pin
12 of
U2120D.
The
momentary
Hi
at
pin
3
activates
U2120B
and
its
output
goes
LO
to
disable
U2120C
(pin
3
already
LO).
The
output
of
U2120C
goes
HI
to
disable
the
Timer
so
it
operates
in
the
display-skip
mode.
The
HI
at
pin
10
of
U2120C
also
holds
U2120B
enabled
so
it
maintains
control
of
the
flip-flop.
Circuit
Description—7613/R7613
Service
The
Single-Shot
Lockout
stage
remains
in
this
condition
until
a
positive-going
trigger
pulse
is
applied
to
pin
8
of
U2120C.
This
trigger
pulse
produces
a
LO
at
pin
10
of
U2120C
which
enables
U2120B
and
disables
U2120C.
Now,
the
Timer
can
operate
in
the
normal
manner
for
another
complete
frame.
When
word
six
is
completed,
the
Channel
Counter
produces
another
End-of-Frame
pulse
to
again
lock
out
the
Timer
stage.
Encoding
the
Data
Data
is
conveyed
from
the
plug-in
units
to
the
Readout
System
in
the
form
of
an
analog
code
having
up
to
11
current
levels
(from
zero
to
one
milliampere
in
100
microampere
steps).
The
characters
which
can
be
selected
by
the
encoded
data
are
shown
on
the
Character
Selection
Matrix
(see
Fig.
3-25).
Each
character
requires
two
currents
to
define
it;
these
currents
are
identified
as
the
column
current
and
the
row
current
which
correspond
to
the
column
and
row
of
the
matrix.
The
column
and
row
data
is
encoded
by
resistive
programming
in
the
plug-in
units.
Fig.
3-32
shows
a
typical
encoding
scheme
for
a
voltage-sensing
amplifier
plug-in
unit.
Notice
that
the
10
time-slot
(TS)
pulses.
produced
by
the
Time-Slot
Counter
stage
are
connected
to
the
plug-in
unit.
However,
time-slots
5,
6,
7,
and
10
are
not
used
by
the
plug-in
unit
to
encode
data
when
using
the
Standard
Readout
Format
(see
Table
3-2
for
Standard
Readout
Format).
The
amplitude
of
the
time-slot
pulses
is
exactly
—15
volts
as
determined
by
the
Timer
stage.
Therefore,
the
resultant
output
current
from
the
plug-in
units
can
be
accurately
controlled
by
the
programming
resistors
in
the
plug-in
units.
For
example,
in
Fig.
3-32,
resistors
R10
through
R90
control
the
row
analog
data
which
is
connected
back
to
the
Readout
System.
These
resistors
are
of
fixed
value
and
define
the
format
in
which
the
information
will
be
presented
by
the
Readout
System.
Fig.
3-33A
shows
an
idealized
output
current
waveform
of
row
analog
data
which
results
from
the
10
time-slot
pulses.
Each
of
the
steps
of
current
shown
in
these
waveforms
corresponds
to
100
microamperes
of
current.
The
row
numbers
on
the
left-hand
side
of
the
waveform
correspond
to
the
rows
in
the
Character
Selection
Matrix
shown
in
Fig.
3-35.
The
row
analog
data
is
connected
back
to
the
Readout
System
via
terminal
B37
of
the
plug-in
interface.
The
Column
analog
data
is
defined
by
resistors
R110
through
R190.
The
program
resistors
are
connected
to
the
time-slot
lines
by
switch
closures
to
encode
the
desired
data.
The
data
as
encoded
by
the
circuit
shown
in
Fig,
3-32
indicates
a
100
microvolt
sensitivity
with
the
display
inverted
and
calibrated
vertical
deflection
factors.
This
results
in
the
idealized
output
current
waveforms
shown
in
Fig.
3-33B
at
the
column
analog
data
output,
terminal
A37
of
the
plug-in
interface.
Resistor
R111,
connected
between
time-slot
1
and
the
column
analog
data
output,
encodes
two
units
of
current
during
time-slot
1.
Referring
to
the
3-41
7613

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Tektronix 7613 Specifications

General IconGeneral
BrandTektronix
Model7613
CategoryTest Equipment
LanguageEnglish

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