Table of Contents
Advertisement
output level of U274 is zero volts, R235 sets the do
Frame-A display of all words for a given operating
Centering and R279 adjust the DC Common Mode
mode and plug-in combination . Up to 8 words can be
voltage .
displayed in one frame . Figure 3-8 shows the position
of each word in a complete frame .
Thermal compensation for U232 and 0274 is provided by
four time constants R240 and C240, C237, R250 and
C250, R270, and C270 .
The operation of the B trigger selector is similar, except
for t he signal p ickoff of pin 2 and pin 4 of U474 which is
used to generate the Vertical Signal Out .
VERTICAL SIGNAL OUTPUT AMPLIFIER
READOUT SYSTEM
SN 8053266 & Below
A schematic diagram of the Readout System is given on
diagram 6, in section 8 of this manual (Diagrams and
Circuit Board Illustrations) . This schematic is divided by
gray shaded lines separating the circuitry into major
stages .
These
stages
aid
in
locating
components
mentioned here . Stage name headings in the following
discussion are used to further identify portions of the
circuitry on diagram 6 .
The Readout System provides an alpha-numeric display
of information encoded by the plug-in units . This display
is presented on the crt and is written by the crt beam on
a time-shared basis with the analog waveform display .
The following terms are used to describe the Readout
System :
Character-A
single
number,
letter
or
symbol
displayed on the crt, either alone or in combination
with other characters .
REV NOV 1985
Theory of Operation-7104
Column-One of the vertical lines in the Character
Selection Matrix (see Fig . 3-9) . Columns C-0 (column
zero) through C-10 (column 10 can be addressed by
the system .
Row-One of the horizontal lines in the Character
Selection matrix . Rows R-1 (row 1) through R-10 (row
10) and R-14 (row 14) can be addressed by the
system .
A differential signal is picked off at pin 2 and pin 4 of
U474 and is amplified by U492 .
Before the signal
reaches
the
input
of
U492
it
passes
through
a
Time-Slot-A location in a pulse train . In the Readout
compensation circuit consisting of C483, R483, R486,
System, the pulse train consists of 10 negative-going
L486,
R496,
C492
and
R493 .
The
characteristic
pulses . Each time-slot pulse is assigned a number
impedance of this circuit is 100 ohms differentially and
between 1 and 10 . For example, the first time-slot is
terminates the 50-ohm strip transmission lines running
TS-1 .
from the pickoff points, at pin 2 and pin 4 of U474 . At pin
2 and pin 4 there is an uncertainty in the do common-
Time-Multiplexing-Transmission of data from two or
mode level due to the 5% voltage tolerance of zener
more sources over a common path by using different
diodes VR437 and VR447 . Integrated circuit U452B
time intervals for different signals .
passes on this uncertainty for biasing U492 . The output
signal at J496 is centered at 0 volt by R485 . The Vertical
Signal Out amplitude is 25 millivolts/division of vertical
DISPLAY FORMAT
deflection into a load of 50 ohms, and 0 .5 volt/division of
vertical deflection into a 1
megohm had . Two time
Up to 8 words of readout information can be displayed on
constants R480 and L480, R490 and C490 provide for
the crt . The position of each word is fixed and is directly
thermal compensation .
related to the plug-in unit from which it originated .
Figure 3-8 shows the area of the graticule where the
readout from each plug-in unit is displayed . Notice that
Channel 1 of each plug-in unit is displayed within the top
division of the crt and Channel 2 is displayed directly
LEFT VERT
RIGHT VERT
A HORIZ
B HORIZ
CHANNEL 1
CHANNEL 1
CHANNEL 1
CHANNEL 1
F
__ i
i . *+,~-r,~-~ ~
+++
. ++ ++++-
r
'~___
i t
ax~ . . . . . .
. .
. .
. .
. .
. .
. .
. .
. .
I
LEFT VERT
RIGHT VERT
A HORIZ
B HOR12
CHANNEL 2
CHANNEL 2
CHANNEL 2
CHANNEL 2
(1675-8) 2314-8
Word-A group of related Characters . In the Readout
Figure3-8 . Location of readout display on thecrtidentifyingthe
System, a word can consist of up to 10 characters .
originating plug-in and channel .
3- 2 5
Advertisement
Table of Contents
Need help?
Do you have a question about the 7140 and is the answer not in the manual?