Tektronix 7623A User manual

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TEKTROND©
INSTRUCTION MANUAL
Tektronix, Inc.
P.O. Box 500 es
Beaverton, Oregon 97005 Serial Number 2.
070-1684-00
First
Printing
April
1974

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7623A/R7623A Operators
TABLE OF CONTENTS
LIST OF ILLUSTRATIONS
LIST OF TABLES
SECTION 1 OPERATING INSTRUCTIONS
PRELIMINARY OPERATION
AC POWER SOURCES
AC POWER CORD
OPERATING VOLTAGE
OPERATING TEMPERATURE
RACKMOUNTING
PLUG-IN UNITS
PLUG-IN INSTALLATION AND REMOVAL
CONTROLS AND CONNECTORS
FRONT PANEL CONTROLS AND CONNECTORS
REAR PANEL CONTROLS AND CONNECTORS
OPERATING CHECKOUT
GENERAL
SET-UP INFORMATION
DISPLAY FOCUS
TRACE ALIGNMENT
GRATICULE ILLUMINATION
VERTICAL DEFLECTION SYSTEM
TRIGGERING ‘
HORIZONTAL DEFLECTION SYSTEM
STORAGE OPERATION
BEAMFINDER
Z-AXIS INPUT
GENERAL OPERATING INFORMATION
INTENSITY CONTROL
DISPLAY FOCUS
GRATICULE
LIGHT FILTER
BEAMFINDER
Page
1-1
1-1
1-1
1-1
1-1
1-3
1-3
1-4
1-4
1-5
1-6
1-8
1-10
1-10
1-10
-11
-11
-11
-12
-13
-13
-16
-16 —
=
=.
= =
= = =
-16
-16
-17
-17
-18
-18 —
—_2
=
—
= —

7623A/R7623A Operators
TABLE
OF
CONTENTS
(cont.)
Page
READOUT MODES 1-19
DISPLAY PHOTOGRAPHY 1-19
STORAGE 1-20
CARE OF STORAGE SCREEN 1-21
VERTICAL MODE 1-22
TRIGGER SOURCE 1-23
X-Y OPERATION 1-24
INTENSITY MODULATION 1-24
RASTER DISPLAY 1-25
CALIBRATOR 1-25
SIGNALS OUT 1-26
APPLICATIONS 1-27
SECTION 2 SPECIFICATIONS 2-1
INTRODUCTION 2-1
STANDARD ACCESSORIES 2-9
SECTION 3 RACKMOUNTING INSTRUCTIONS 3-1
INTRODUCTION 3-1
INSTALLATION INSTRUCTIONS 3-1
RACK DIMENSIONS 3-1
SLIDE-OUT TRACKS 3-2
MOUNTING PROCEDURE 3-4
REMOVING OR INSTALLING THE INSTRUMENT 3-5
SLIDE-OUT TRACK LUBRICATION 3-5
SECTION 4 OPTIONS 4-1

LIST OF ILLUSTRATIONS
FRONTISPIECE
Figure 1-1. Location of voltage-selector jumper.
Figure 1-2. Front panel controls and connectors.
Figure 1-3. Rear panel controls and connectors.
Figure 1-4. Definition of measurement lines on the graticule.
Figure 1-5. Location of Readout Mode switch.
Figure 1-6. Location of Calibrator jumper on Storage circuit board.
Figure 3-1. Slide out track assembly and mounting hardware.
Figure 3-2. Vertical mounting position of the left stationary section and the
securing hole location. These dimensions also apply to the right front rail.
Figure 3-3. Details for mounting stationary sections.
Figure 3-4. Installing and removing the instrument.
Figure 3-5. Adjusting the slide out tracks for smooth sliding action.
Figure 3-6. Dimensional drawing.
LIST OF TABLES
TABLE 1-1. Power Cord Color Coding
TABLE 1-2. Regulating Range and Fuse Data
TABLE 2-1. ELECTRICAL
TABLE 2-2. ENVIRONMENTAL
TABLE 2-3. PHYSICAL
TABLE 2-4. SYSTEM SPECIFICATIONS
7623A/R7623A Operators
Page
1-2
1-5
1-9
1-17
1-19
1-26
3-1
3-2
3-3
3-4
3-5
3-6
1-1
1-3
24
2-8
2-8
2-10

7623 OSCHLOSCOP!
5
The
Tektronix
7623A/R7623A
Storage
Oscilloscope
is
a
solid-state
instrument
designed
for
fast
writing
rate
storage
applications.
The
7623A
operates
in
three
display
modes—NON
STORE,
STORE,
and
SAVE,
and
has
four
storage
modes—
BISTABLE,
VAR
PERSIST,
FAST
BISTABLE,
and
FAST
VAR
PERSIST.
This
instrument
has
three
plug-in
compartments
that
accept
any
7-series
plug-in
units
to
form
a
highly
flexible
measurement
system.
7623A/R7623A Operators ®
—_

Section 1—7623A/R7623A Operators
OPERATING INSTRUCTIONS
PRELIMINARY OPERATION
To effectively use the 7623A/R7623A Storage Oscilloscope, the operation and capabilities of the instru-
ment must be known. This section provides preliminary operating information, describes operation of con-
trols and connectors, and provides an operating checkout procedure.
AC POWER SOURCES
This instrument is intended to be operated from a single-phase, earth-referenced power source having
one current-carrying conductor (the Neutral Conductor) near earth potential. Operation from power sources
where both current-carrying conductors are live with respect to earth (such as phase-to-phase on a three-wire
system) is not recommended since only the Line Conductor has over-current (fuse) protection within the
instrument.
AC POWER CORD
This instrument has a three-wire power cord with a three-terminal polarized plug for connection to
the power source and safety-earth. The safety-earth terminal of the plug is directly connected to the in-
strument frame. For electric-shock protection, insert this plug only in a mating outlet with a safety-earth
contact or otherwise connect the frame to a safety earth system. The color-coding of the cord conductors
is in accordance with recognized standards as shown in Table 1-1.
TABLE 1-1
Power Cord Conductor Identification
Conductor Color Alternate Color
Ungrounded (Line) Brown Black
Grounded (Neutral) Blue White
Grounding (Earthing) Green-Yellow Green-Yellow
The 7623A/R7623A can be operated from either a 110-volt or a 220-volt nominal line-voltage source.
In addition, three operating ranges can be selected within each nominal line voltage source. Use the follow-
ing procedure to obtain correct instrument operation from the line voltage available:
1. Disconnect the instrument from the power source.
2. Remove the six screws securing the power unit (nine screws in the R7623A;; see Figure 1-1).
3. Slide the power unit out of the rear of the chassis.
REV. C, NOV. 1976 1-1

Operating Instructions—7623A/R7623A Operators
POWER UNIT
SECURING
SCREWS
ALT SPARE VOLTAGE-SELECTOR
FUSE JUMPER JUMPER
Figure 1-1. Location of voltage-selector jumper.
4. To convert from 110-volts to 220-volts nominal line voltage, or vice versa, remove the voltage-
selector jumper and replace it with the spare jumper stored on the pins adjacent to the voltage selector
area (see Figure 1-1). The jumpers are color coded to indicate the nominal voltage for which they are in-
tended; brown for 110-volt nominal operation and red for 220-volt nominal operation. Change the fuse to
provide protection for the selected nominal line voltage. Use the fuse located in the Alt Fuse holder on the
Rectifier board (see Figure 1-1 for fuse location and Table 1-2 for fuse type). Also, change the line-cord
plug to match the power-source receptacle or use a suitable adapter.
1-2 ®
>

Operating Instructions—7623A/R7623A Operators
5. To convert the instrument from one regulating range to another, remove the voltage selector
jumper and re-install it on the set of pins corresponding to the desired regulating range. The proper reg-
ulating range will center about the average line voltage to which the instrument is to be connected (see
Table 1-2).
TABLE 1-2
Regulating Range and Fuse Data
Pins Regulating Range
Selected
110-volts (nominal) 220-volts (nominal)
LOW 90 to 110 volts 180 to 220 volts
MED 99 to 121 volts 198 to 242 volts
HI 108 to 132 volts 218 to 262 volts
Line Fuse 3.2 A slow-blow 1.6 A slow-blow
OPERATING TEMPERATURE
The 7623A can be operated where the ambient air temperature is between 0°C and +50°C. This in-
strument can be stored in ambient temperatures between —55°C and +75°C. After storage at temperatures
beyond the operating limits, allow the chassis temperature to come within the operating limits before power
is applied.
The 7623A is cooled by air drawn in through the top, side, and bottom panels and exhausted through
the rear panel. Components that require most cooling are mounted externally on a heat radiator. Adequate
clearance must be provided on all sides to allow heat to be dissipated from the instrument. Do not block or
restrict the air flow through the holes in the cabinet or the heat radiator. Maintain the clearance provided
by the feet on the bottom and allow about two inches clearance on the top, sides, and rear (more if possible).
The R7623A is cooled by air drawn in through the air filter on the rear panel and exhausted through
ports on the right side of the instrument. Adequate clearance must be provided at these locations. Allow
at least one and one-half inches clearance behind the air filter and at least one inch on the right side.
A thermal cutout interrupts power to the instrument if the internal temperature exceeds a safe oper-
ating level. Power is automatically restored when the temperature returns to a safe level. Operation in
confined areas or close to a heat source may cause the thermal cutout to open.
RACKMOUNTING
Instructions and dimensional drawings for rackmounting the R7623A are located in Section 3.
® 1-3

Operating Instructions—7623A/R7623A Operators
PLUG-IN UNITS
The 7623A will accept up to three 7-series plug-in units. This plug-in feature permits a variety of
display combinations and also allows selection of bandwidth, sensitivity, display mode, etc. to meet many
measurement requirements. In addition, it allows expansion of the oscilloscope system to meet future
measurement requirements. The overall capabilities of the resultant system are in large part determined
by the characteristics of the plug-in selected. For complete information on plug-ins available for use with
this instrument, see the current Tektronix, Inc., catalog.
PLUG-IN INSTALLATION AND REMOVAL
To install a plug-in unit into one of the plug-in compartments, align the slots in the top and bottom
of the plug-in with the associated guide rails in the plug-in compartment. Push the plug-in unit firmly into
the plug-in compartment until it locks into place. To remove a plug-in, pull the release latch on the plug-in
unit to disengage it and pull the unit out of the plug-in compartment. Plug-in units can be removed or in-
stalled without turning off the instrument power.
It is not necessary that all of the plug-in compartments be filled to operate the instrument; the only
plug-in units needed are those required for the measurement to be made. However, at environmental ex-
tremes, excess radiation may be radiated into or out of this instrument through the open plug-in compart-
ments. Blank plug-in panels are available from Tektronix, Inc., to cover the unused compartment; order
Part No. 016-0155-00.
When the 7623A is calibrated in accordance with the calibration procedure given in the Service manual,
the vertical and horizontal gains are standardized. This allows calibrated plug-in units to be changed from
one plug-in compartment to another without recalibration. However, the basic calibration of the individual
plug-in units should be checked when they are installed in this system to verify their measurement accuracy.
See the plug-in unit instruction manual for verification procedure.
Special purpose plug-in units may have specific restrictions regarding the plug-in compartments in
which they can be installed. This information will be given in the instruction manual for these plug-in units.
1-4

Operating Instructions—7623A/R7623A Operators
CONTROLS AND CONNECTORS
The major controls for operation of the 7623A are located on the front panel of the instrument. These
are illustrated in Figure 1-2. Figure 1-3 shows the location of rear panel controls and connectors. The follow-
ing is a brief description of the controls and connectors shown in Figures 1-2 and 1-3. More detailed operat-
ing information is given under General Operating Information.
22
oe
”
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Abeba
} TeREEREE
DUAL TRACE AMPLIFIER 7A2 DUAL TRACE AMPLIFIER
; 6
7A26
*Changed to INTERNAL ADJUST SN B130000-up.
Figure 1-2. Front panel controls and connectors.
REV. B, NOV. 1976 1-5
1684-01

Operating Instructions—7623A/R7623A Operators
FRONT PANEL CONTROLS AND CONNECTORS
1-6
The following descriptions are referenced to Figure 1-2.
(1) VERT MODE: Selects vertical mode operation.
LEFT: Selects signals from the left vertical amplifier compartment for display.
ALT: Selects signals from both vertical compartments for display on alternate
sweeps (dual trace).
ADD: Algebraically adds the signals from both vertical compartments and dis-
plays the sum.
CHOP: Selects signals from both vertical compartments for display (dual trace).
The display switches between both vertical compartment signals, during
the sweep, at a one megahertz rate.
RIGHT: Selects signals from the right vertical amplifier compartment for display.
(2) TRIG SOURCE: Selects the source of the internal trigger for the plug-in unit in the hori-
zontal compartment.
LEFT: Selects the left vertical compartment as the internal trigger source.
VERT MODE: Internal trigger signals are determined by the VERT MODE switch.
RIGHT: Selects the right vertical compartment as the internal trigger source.
(3) INTENSITY—Controls the brightness of the display.
G4) READOUT—Turns on the Readout system and controls the brightness of the Readout display.
(Option 1 deletes this function.)
G) BEAMFINDER—When pressed, this switch limits the display to within the graticule area.
(6) GRATICULE ILLUM—Controls the illumination of the graticule.
—~

Operating Instructions—7623A/R7623A Operators
a FRONT PANEL CONTROLS AND CONNECTORS (cont.)
@
@)
®
@)
@®
@®)
ERASE-—Initiates erase cycles; either MANual or PERIODIC.
MANual: When pressed, initiates an erase cycle to erase the stored display and
provide a single-shot reset command to the plug-in time-base unit.
Operation is locked out in SAVE display mode.
PERIODIC: Controls the time between automatic erase cycles. If the erase period
ends during a sweep, the erasure is delayed till the end of that sweep.
This control has a counterclockwise OFF detent position. Operation
is locked out in the SAVE display mode.
PERSISTENCE—Controls the view time of the VAR PERSIST and FAST VAR PERSIST
stored displays. Operation is locked out in the SAVE display mode.
FAST—Used in conjunction with the VAR PERSIST and BISTABLE storage selections to choose
the fast transfer storage modes of either FAST VAR PERSIST or FAST BISTABLE.
VAR PERSIST-—Selects the Variable Persistence storage mode. The stored display is of variable
intensity dependent upon the setting of the STORAGE LEVEL, density of charge deposited
when storing, etc. The stored display can be erased at acontrollable, continuous rate determined
by the setting of the PERSISTENCE control. When not being erased, the view time is limited by
the natural bright fading of the storage target.
BISTABLE-Selects the BISTABLE storage mode. The stored display is substantially of two
fixed intensity levels; written (bright) and unwritten (background). An erase cycle returns the
display to the unwritten state.
POWER -—Switch and indicator. Switch applies power to the instrument and the indicator illumi-
nates to indicate the power is on.
CALIBRATOR-—Positive going square wave or dc voltage selected by an internal jumper. Output
voltage at pin jacks (4 V, 0.4 V, and 40 mV).
STORAGE LEVEL—Controls the voltage level on the storage targets. Adjusts writing speed in
FAST BISTABLE, VAR PERSIST, and FAST VAR PERSIST.
SAVE INTEN—Used in conjunction with SAVE to control the storage viewing intensity. At
reduced intensity, the view time of the stored VAR PERSIST display is proportionately ex-
tended.
SAVE -Selects the SAVE display mode. The stored display is retained at a controllable SAVE
INTENSITY and the erase functions are locked out. The time-base unit is inhibited except
when the SAVE mode is entered from STORE before a sweep occurs. If this is done, the dis-
play will wait in the STORE mode and enter SAVE automatically at the end of the next
1-7

Operating Instructions—7623A/R7623A Operators
FRONT PANEL CONTROLS AND CONNECTORS (cont.)
occuring sweep. This is referred to as the ‘babysitting’ mode.
©
FAST LEVEL CENTER—Adjusts the voltage level of the FAST target relative to the viewing
target and, therefore, the tracking of the STORAGE LEVEL for the two targets (Internal
adjustment for instruments SN B130000 - up).
STORE-Selects the STORE display mode.
NON STORE-Selects conventional display mode. Storage system is inoperative.
TRACE ROTATE—Adjusts alignment of the trace with the horizontal graticule line.
FOCUS—Provides adjustment for display definition.
CAMERA POWER-—Three-pin connector on crt bezel provides power output and receives
ORORORORS)
remote single-sweep reset signal from compatible camera systems.
REAR PANEL CONTROLS AND CONNECTORS
The following descriptions are referenced to Figure 1-3.
(23) FUSE-—Line voltage fuse.
REMOTE ERASE IN—Provides external connection for remote erase.
(25) EXT SS RESET IN—Remote single sweep reset.
EXT Z AXIS IN—Input for intensity modulation of the crt display.
(21)
VERT
SIG
OUT—Vertical
signal
selected
by
TRIG
SOURCE
switch
(LEFT,
RIGHT,
ALT,
and
ADD).
+
GATE
OUT—Gate
signal
selected
by
gate
selector
switch
(Main,
Auxiliary,
and
Delay).
+ SAWTOOTH OUT~—Positive-going sawtooth from time-base unit.
1-8 REV. B, NOV. 1976

Operating Instructions—7623A/R7623A Operators
$$ READY OUT (7603)
REMOTE ERASE IN (76137628
)
DECREASES INTENSITY
THIS INSTRUMENT 1S CONNECTED
Fuse e
3.28 SLOW 100"120V RANGE
1BASLOW 200-240V RANGE
ALTERNATE FUSE INSIDE.
" VERT SiG OUT
EXT SS RESET IN MAIN
t © AUXIUARY a e
EXT 2 AXIS IN wate +GATE OUT
E1V MAK = S000
POSITIVE SIGNAL
FOR[_}V¥.+10% JUMPERS
INSIDE FREQUENCY 50 TOL iz,
+ SAWTOOTH
ouT
PNa86. 2198.00
Seog
Figure 1-3. Rear panel controls and connectors.
1-9

Operating Instructions—7623A/R7623A Operators
OPERATING CHECKOUT
GENERAL
The following Operating Checkout provides a means of verifying instrument operation and basic
calibration without removing the covers or making internal adjustments. Since it demonstrates the use
of all controls and connectors, it can also be used to provide basic training on the operation of this in-
strument. If re-calibration of the 7623A appears to be necessary, see the Calibration procedure in the
Service manual. If re-calibration of a plug-in unit is indicated, see the Instruction manual for the appro-
priate plug-in unit.
SET-UP INFORMATION
1. Set the front-panel controls as follows:
INTENSITY Counterclockwise
FOCUS Midrange
GRATICULE ILLUM As desired
VERT MODE LEFT
TRIG SOURCE VERT MODE
Display Selection NON STORE
READOUT INTENSITY Off
Momentary switches (BEAM FINDER and MAN ERASE) are not actuated unless they are pressed.
2. Connect the 7623A to a power source which meets the voltage and frequency requirements of
this instrument. The applied voltage should be near the center of the voltage range marked on the rear
panel (see Operating Voltage in this section for information on converting this instrument from one
operating voltage to another).
3. Install Tektronix 7A-series amplifier units (with one megohm input impedance) into both the
left and right vertical plug-in compartments. Install a 7B-series time-base unit into the horizontal com-
partment. Be sure that plug-in units are calibrated.
4. Push the POWER switch to turn the instrument on. Allow several minutes warmup before
proceeding.
5. Set both vertical units for a deflection factor of two volts/division and center the vertical
position controls. Set both vertical units for AC input coupling.
6. Set the time-base unit for a sweep rate of one millisecond/division in the auto, internal trigger
mode.
7. Advance the INTENSITY control until the trace is at the desired viewing level (near midrange).
Advance the READOUT INTENSITY control (out of the detent position) until the readout display is at
the desired viewing level. (Option 1 deletes the Readout system.)
1-10 ®

Operating Instructions—7623A/R7623A Operators
DISPLAY FOCUS
8. Adjust the FOCUS adjustment for a sharp, well-defined display over the entire trace length. If a
properly focused display cannot be obtained with the FOCUS adjustment, the internal Astigmatism adjust-
ment must be reset; see the Calibration section of the Service manual.
TRACE ALIGNMENT
9. Position the trace with the left vertical unit position control! so it coincides with the center hori-
zontal line of the graticule. If the trace is not parallel to the center horizontal line of the graticule, see
Trace Rotation adjustment procedure in Calibration section.
10. Connect the 4 V calibration pin-jack to the input of the left vertical unit with a BNC to pin-jack
cable (supplied accessory) and adjust the time-base unit for a stable display.
GRATICULE ILLUMINATION
11. Rotate the GRATICULE ILLUM control throughout its range and notice that the illumination of
the graticule lines increases as the control is turned clockwise (most obvious with tinted filter installed). Set
the control so the graticule lines are illuminated as desired.
VERTICAL DEFLECTION SYSTEM
12. Set both vertical units for a deflection factor of one volt/division. The display amplitude should
be four divisions. Note the exact display amplitude for step 15.
13.
Notice that the position control of only the left vertical unit has an effect on the position of the
display. Position the display to the upper half of the graticule.
14. Press the RIGHT button of the VERT MODE switch. Remove the calibrator signal from the left
vertical and connect it to the right vertical. The display amplitude should be four divisions within 0.12 div-
ision. Note the exact display amplitude for the next step.
15. Acorrect display in both steps 12 and 14 indicates that the 7623A Vertical Deflection System and
the vertical plug-in units are calibrated. If the displays noted previously are both outside the given tolerance
in the same direction (i.e., high or low), the Vertical Gain or 4 Volts calibrator adjustment may need re-
adjustment. Otherwise, check the calibration of the vertical plug-in units.
16. Notice that the position control of only the right vertical unit has an effect on the position of
the display. Position the display to the lower half of the graticule. Set both vertical units for a deflection
factor of two volts/division. Connect the calibrator signal to both vertical units by using a dual input coup-
ler ora BNC T connector.
17. Press the ALT pushbutton of the VERT MODE switch. Notice that two traces are displayed on
the crt. The top trace is produced by the left vertical unit and the bottom trace is produced by the right
vertical unit. Set the sweep rate to 50 milliseconds/division. Notice that the display alternates between
the left and right vertical units after each sweep. Turn the sweep rate switch throughout its range. Notice
® 1-11

Operating Instructions—7623A/R7623A Operators
that the display alternates between vertical units at all sweep rates.
18. Press the CHOP push button of the VERT MODE switch. Turn the sweep rate switch throughout
its range. Notice that a dual-trace display is presented at all sweep rates, but unlike ALT both vertical units
are displayed on each sweep in a time-sharing manner. Return the sweep rate to 0.5 millisecond/division.
19. Press the ADD push button of the VERT MODE switch. The display should be the algebraic sum
of both signals. Notice that the position control of either vertical unit moves the display. Return the VERT
MODE switch to LEFT and disconnect the signal to the right amplifier unit.
TRIGGERING
20. Center the display on the crt with the left vertical unit position control. Sequentially press all of
the VERT MODE switch buttons. Notice that a stable display is obtained in all positions of the VERT MODE
switch (straight line in RIGHT position).
21. Press the LEFT push button of the TRIG SOURCE switch. Again, sequentially press all of the
VERT MODE buttons. Notice that the display is again stable in all positions, as in the previous step.
22. Press the RIGHT push button of the TRIG SOURCE switch. Sequentially press all of the VERT
MODE buttons and notice that a stable display cannot be obtained in any position. This is because there
is no input signal connected to the right vertical unit. Return the TRIG SOURCE switch to VERT MODE.
Remove calibrator signal from left vertical unit and connect it to right vertical unit.
23. Center the display on the crt with the right vertical unit position control. Sequentially press
all the VERT MODE switch buttons. Notice that a stable display is obtained in all positions of the VERT
MODE switch (straight line in LEFT position).
24. Press the RIGHT push button of the TRIG SOURCE switch. Again, sequentially press all of
the VERT MODE buttons. Notice that the display is again stable in all positions as in the previous step.
25. Press the LEFT push button of the TRIG SOURCE switch. Sequentially press all of the VERT
MODE buttons and notice that a stable display cannot be obtained in any position since no signal is con-
nected to the input of the left amplifier unit.

Operating Instructions—7623A/R7623A Operators
HORIZONTAL DEFLECTION SYSTEM
26. Disconnect all input signals and set the TRIG SOURCE to VERT MODE. Position the start of
the
sweep to the left graticule line with the time-base unit position control.
27.
Connect a 10X probe to the input of the right vertical unit. Set the right vertical unit for a
deflection factor of 10 volts/division and set the VERT MODE switch to RIGHT. Set the time-base unit
for a sweep rate of five milliseconds/division.
NOTE
The following step is based on an accurate 60-hertz line frequency. For
other line frequencies, this procedure will need to be changed accordingly.
28. Connect the probe tip to a line-voltage source. The display should show three complete cycles
over the 10 divisions within 0.3 division. A correct display indicates that the 7623A Horizontal Deflection
System and the time-base plug-in unit are correctly calibrated. If the display is outside the given tolerance,
either the 7623A or the time-base unit needs to be recalibrated. Refer to the Calibration section of the Ser-
vice manual, and to the time-base unit manual for adjustment procedure.
29. Disconnect the probe from the line-voltage source and the right vertical unit. Set the VERT
MODE switch to LEFT and set the time-base unit for a sweep rate of 0.5 millisecond/division. Disconnect
all cables.
STORAGE OPERATION
30. Connect the 4 V Calibrator signal to the input connector of the left vertical unit and set the
deflection factor for one volt/division. Set the time-base unit for single-sweep operation at 0.5 millisec-
ond/division. Be sure the time-base unit is triggered and the INTENSITY control is set to midrange.
31. Press the STORE and BISTABLE push buttons.
32. Press the MANual ERASE push button. If the calibrator waveform does not store, increase
the INTENSITY slightly and press the ERASE button again. If necessary, repeat this sequence until a
stored display is obtained.
33. Press the SAVE push button. The waveform stored in the previous step should remain on the
crt. It may be necessary to adjust the SAVE INTEN control to view the display. Turn the SAVE INTEN
control throughout its range and observe its effect on the display: from dark at the counterclockwise end
to bright screen at the clockwise end.
34. Press the ERASE button and notice that the display cannot be erased. The erase function is
locked out in the SAVE mode.

Operating Instructions—7623A/R7623A Operators
35. Set the STORAGE LEVEL and PERSISTENCE controls fully counterclockwise. Press the
STORE, then the VAR PERSIST push buttons. Observe that an erase cycle and sweep occurs (when switch-
ing between the BISTABLE and VAR PERSIST modes) and that the screen goes dark except for the stored
display.
36. Slowly turn the PERSISTENCE control clockwise and notice that the stored display fades into
the background. (A background lighting will be observed as the PERSISTENCE control is advanced clock-
wise. This is caused by the positive persistence pulses being applied to the Front storage mesh.) The PER-
SISTENCE control adjusts the length of time the stored display is retained in the VAR PERSIST mode.
Return the PERSISTENCE control to its fully counterclockwise position.
37. Press the ERASE push button, then set the PERSISTENCE control to midrange just long enough
for the display to fade out. Quickly return the PERSISTENCE control to its counterclockwise end. Slowly
increase the STORAGE LEVEL (clockwise) and notice that the faded display again becomes visible against
a background that begins to brighten. This background lighting results from the increased voltage (STORAGE
LEVEL) on the Front Mesh storage surface. Eventually, the unstored area of the Front Mesh will become
brighter (charge positive) until the stored (written) area can no longer be distinguished from the bright back-
ground. The ‘view time’ is the length of time the display is viewable from the moment of signal storage
until it is obscured by the brightness of the background as described above.
As the STORAGE LEVEL is increased (turned clockwise), the writing speed (sensitivity of the Front
Mesh storage surface to faster, smaller-amplitude signals) increases. However, as the writing speed is in-
creased, there is a corresponding reduction of the ‘view time’.
38. Turn the PERSISTENCE, STORAGE LEVEL, and INTENSITY controls fully counterclock-
wise and set the time-base unit for auto triggering at a sweep rate of 0.5 second/division.
39. Set the PERSISTENCE control to midrange and slowly increase the INTENSITY (clockwise)
until the trace appears. Vary the PERSISTENCE control setting and notice that the trace can be made to
build up or to fade more quickly, depending on the control setting. Varying the INTENSITY control also
affects the display in the same manner. Return the PERSISTENCE control to midrange and slowly de-
crease
the INTENSITY to the point where the trace just extinguishes. Adjust the STORAGE LEVEL con-
trol clockwise and notice that the trace becomes visible again. This is because the writing speed has been
increased as described in step 37.
40. Turn the PERSISTENCE, STORAGE LEVEL, and INTENSITY controls fully counterclock-
wise and set the time-base unit for auto triggering at a sweep rate of 0.5 millisecond/division.
41. Press the STORE, BISTABLE, and FAST push buttons.
42. Press the ERASE push button and notice that the screen background appears to alternate be-
tween bright and dim. This indicates that the sweep and transfer functions are operating—the sweep occurs
(writing on the Fast Mesh), then the written display is transferred to the Front Mesh. The ERASE control
should still be in the MANual (detent) position so no erase cycle occurs.
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