Tektronix T921 User manual

Tektronix, Inc .
P .O . Box500
Beaverton, Oregon 97077
070-1982-01
TEKTRONIX
T921 /T922/T922
R
15
MHz
OSCILLOSCOPES
WITH OPTIONS
INSTRUCTION
MANUAL
Serial Number
First Printing JULY 1975

WARRANTY
All TEKTRONIX
instruments are warranted against de-
fective materials
and
workmanship for
one
year . Any
questions with respect
to
the warranty should
be
taken up
with your TEKTRONIX Field Engineer or representative .
All requests for repairs and replacement parts should be
directed to the TEKTRONIX Field Office or representative
in your area . This will assure you the fastest possible
service
.
Please include the instrument
Type
Number
or
Part Number and Serial Number with all requests for parts
or service .
Specifications and price change privileges reserved .
Copyright © 1975, 1976 by Tektronix, Inc ., Beaverton,
Oregon . Printed in the United States of America . All rights
reserved . Contents of this publication may not be
reproduced in any form without permission of Tektronix,
Inc .
U .S .A . and foreign TEKTRONIX products covered by
U .S .
and foreign patents and/or patents pending .
TEKTRONIX is a registered trademark of Tektronix, Inc .

REV . B JUL 1977
TABLE
OF
CONTENTS
T921/T922/T922R
Page THE FOLLOWING
SERVICING INSTRUCTIONS
AREFOR QUALIFIED SERVICE PERSONNEL
LIST OF ILLUSTRATIONS
ii
ONLY
SECTION 4 ADJUSTMENTS
Page
LIST OF TABLES
III
Limits and Tolerances 4-1
Adjustment Interaction 4-1
Partial Procedures 4-1
Test Equipment Required 4-1
Preliminary
Procedure 4-2
SECTION 1 SPECIFICATIONS
A . Display and Power Supply 4-4
Electrical 1-1
B . Vertical Amplifier 4-6
Environmental 1-3
C . Time Base 4-10
Physical 1-3
Standard Accessories 1-5
SECTION 5 SERVICE INFORMATION
Recommended Accessories 1-6
Cabinet Removal 5-1
Preventive
Maintenance 5-1
Troubleshooting 5-2
Corrective Maintenance 5-10
SECTION 2
OPERATING INSTRUCTIONS
T922R Line Voltage and
Range
Operating Voltage
2-1
Selection 5-21
Safety
Information 2-1
Repackaging For Shipment 5-21
Function of
Controls, Connectors
and Indicators, T921 and T922 SECTION 6 ELECTRICAL REPLACEABLEPARTS
A . Display 2-1
B . Vertical Amplifier 2-3
OPTIONS
C . Time Base 2-5
SECTION 7
CIRCUIT DESCRIPTION AND DIAGRAMS
Function of Controls, Connectors
and Indicators, T922R
Block Diagram
A . Display 2-7
CRT and Vertical Amplifier
B . Vertical Amplifier 2-8
Power Supply
C . Time Base 2-8
Vertical Input (T921)
First Time Operation 2-10
Vertical
Input (T922)
Probe Compensation 2-13
Vertical Switching (T922)
Applications
2-13
Trigger (Late)
T922R
Rackmounting 2-17
Trigger (Early)
Sweep & Horizontal Amplifier
T922R Single Sweep, Buffer, & Z Axis
T922R Scale Illum, +32 V P .S ., Vert Out,
SECTION 3 PERFORMANCE CHECK
F&R Sw
.
T922R
Circuit Board Interconnections
Limits and Tolerances 3-1
Test Equipment Required 3-1 SECTION 8 MECHANICAL REPLACEABLEPARTS
. Preliminary
Procedure 3-2
Performance Check Procedure 3-3 CHANGE INFORMATION

T921/T922/T922R
LIST OF
ILLUSTRATIONS
REV . A, JUNE 1976
Fig .
No .
Description
Page
No .
Fig .
No .
Description
Page
No .
1-1 T921/T922/T922R 15 MHz
oscilloscopes . Frontis
4-1 T922R
adjustment locations . 4-3
1-2 T922R
dimensional drawing . 1-4
4-2 Power supply adjustment location
1-3 T921/T922 dimensional
drawing . 1-5
(bottom of T921 and T922) . 4-4
2-1 Display front panel controls and 4-3 Interface board adjustment locations . 4-5
connectors . 2-2 4-4 Vertical amplifier adjustment locations
2-2 Rear panel controls and connectors . 2-3 (bottom view of T921 and T922) . 4-7
2-3 Left side of cabinet . 2-4 4-5 Display of correct (idealized) attenuator
2-4
Bottom of cabinet . 2-4
compensation .
4-8
2-5 Vertical
amplifier front panel controls . 2-5 4-6
Time base adjustment
locations . 4-11
2-6 Time
base front panel controls and
connectors .
2-6 5-1 Troubleshooting chart .
5-4
2-7 T922R display controls,
connectors, and 5-2 Color code for resistors and capacitors .
5-6
indicators .
2-7 5-3 Lead configuration for semiconductor
2-8
T922R vertical amplifier controls,
devices . 5-7
connectors
and indicators . 2-9 5-4
Multi-cohnector holder orientation . 5-8
2-9 T922R time
base controls, connectors
5-5 Pin connector replacement . 5-12
and indicators .
2-10 5-6 Shaft-knob removal .
5-13
2-10
Probe compensation . 2-14 5-7
T921 and T922 circuit board locations .
5-13
2-11 Effects
of probe compensation . 2-14 5-8
T921 and T922 circuit board locations . 5-15
2-12 Peak-to-peak
voltage measurement . 2-15 5-9
T922R circuit board locations . 5-17
2-13 Instantaneous voltage
measurement . 2-15 5-10 T922R
vertical module replacement . 5-18
2-14 Phase difference .
2-16 5-11 T922R horizontal
module replacement . 5-18
2-15 Time duration .
2-16 5-12 T922R interface
board replacement . 5-19
2-16 Risetime .
2-17 5-13 T922Rpowermodule replacement
. 5-19
2-17
T922R rackmounting methods .
2-19 5-14 T922R scale illum assembly
3-1 Deflection
accuracy and X gain check
replacement . 5-20
test setup .
3-3 5-15 T922R
line-voltage and range selection . 5-21
3-2 T922R rear input test
setup . 3-4
3-3 Bandwidth check test setup .
3-6
7-1
Foldback circuit action .
3-4 Triggering and Z-axis input check test 7-2
Timing diagram : sweep generatorand gate .
setup .
3-7 7-3
Timing
diagram of signals generated
3-5 Timing
accuracy check test setup . 3-8 ' during
a single-sweep display .
3-6 SWEEP RAMP
OUT display . 3-10 7-4 Bench
version T922+33voltpowersupply .
3-7 SWEEP GATE OUT
display . 3-10 7-5 Simplified block
diagram of the vertical
3-8
TV trigger check test setup .
3-11 output amplifier circuit .

LIST OF TABLES
T921/T922/T922R
Table Title Page
No . No .
1-1 Electrical Characteristics 1-1
1-2 Environmental Characteristics 1-3
1-3 Physical Characteristics
1-3
3-1 Test
Equipment 3-1
3-2 Deflection Accuracy 3-3
3-3 Normal Sweep Timing Accuracy 3-9
3-4 Magnified Sweep Timing Accuracy 3-9
4-1 Test Equipment
4-1
5-1 Power Supply
Tolerance 5-3
7-1 Attenuator and Gain Switching
Sequence
7-2 Attenuator and Gain Switching

T921 /T922/T922R
Fig . 1-1
. T921/T922/T922 R 15 MHz oscilloscopes .
REV . A, JUNE 197 6

This manual includes
instructions for the T921, T922
and T922R portable
oscilloscopes . The T922 is a 15
MHz,
dual trace,
oscilloscope and the T921 is a 15 MHz, single
trace oscilloscope
. The Vertical Amplifier,
either single
trace or dual trace, provides calibrated
deflection factors
from 2 mV to 10 V/div .
The TimeBase provides stable
triggering over the
full bandwidth of the Vertical
Amplifier(s) and
provides calibrated sweep rates from
0 .5 s/div to 0 .2 Ns/div
. A variable X1 to X10 magnifier
extends the
maximum sweep rate to 20 ns/div .
The T992R is a
rackmount verison of the T922 os-
cilloscope which
takes 5-1/4 inches of rack space .
Characterist ic
Probe Adjust Output
Voltage
(0°Cto
+40° C)
Repetition Rate
Z-Axis Input
Sensitivity
Signal Polarity
T921 and T922
T922R
REV . C APR
1977
PerformanceRequirement
A . DISPLAY
Approximately
0 .5
V .
Approximately 1 kHz .
5 volt
signal causes a noticeable
decrease in intensity .
Positive going from ground .
Either polarity of signal can be
applied, depending upon internal
jumper connections
.
SPECIFICATIONS
TABLE 1-1
Electrical
Features
added to the rackmount version
include : single
sweep ; rear panel outputs for Sweep Gate,
Sweep Ramp,
and Vertical Signal ; internally
selectable Z Axis polarity ;
user selection of the CHOP or
ALT dual trace modes ; and
switch-selectable
front-panel or rear-panel inputs for
CH 1, CH 2,
and EXT TRIG signals .
The following instrument specifications
apply over an
ambient temperature range of
0°C to +45°C unless
otherwise specified .
The Adjustment Procedure in Section
4, when
performed completely, allows the T921/T922/
T922R to
meet the electrical specifications listed in
Table
1-1 .
Characteristic
Line Frequency

1 50 to 60 Hz .
Maximum Power
Consumption
CRT Display
Display Area
Trace Rotation
Range
Standard
Phosphor
Nominal Accel-
erating Potential
Section 1-T921/T922/T922R
36 W, 0 .35
A
at 60 Hz, 120
V
line .
8 x 10 cm .
Adequate to
align trace with
horizontal
center line .
P31 .
PerformanceRequirement
12,400 V .
B . VERTICAL AMPLIFIER
Usable Frequency
Range
Dc to 5 MHz .
Deflection Factor
Maximum Input
30 V
(dc
+
peak ac) 30 V p-p at
Range 2
mV/div
to
10 V/div ;12steps in a 1-
Voltage 1 kHz or less
.
2-5
sequence .
Input Impedance Approximately 10 kit .
Accuracy
Power Source (T922R 120 V-240
V Range and
Line Voltage
HI-LO adjustments are not exter-
+20° C to Within 3% .
Ranges (ac,rms)
nally accessible) .
+30° C
120 V Range HI-108 to 132 V .
O' C to +45 1 C Within 4% .
LO-90 to 110 V .
Uncalibrated Continuously variable between
240 V Range HI-216
to 250
V . (VAR) Range settings . Extends deflection
factor
LO-198 to 242
V .
to at least 25
V/div (at least 2 .5 :1) .

Specifications-T921 /T9~2/T922R
Chara cteristic

Performance Requirement
B . VERTICAL AMPLIFI ER (co nt)
TABLE 1-1 (cont)
Characteristic
Sweep Rate
Calibrated Range
Accuracy
+20° C to
+30° C
X-Y
Operation
Unmagnified
Magnified
O' C to +45° C
Unmagnified
Magnified
Variable
Magnifier
Deflection Factor
Variable
Magnifier
X10
X1
X-Axis Bandwidth
T921 & T922
T922R
Input Resistance
Input Capacitance
T921 &T922
T922R
Phase Difference
Between X- and
Y-Axis
Amplifiers
C
.
TIME
BASE
0 .5 s/div to 0 .2,us/div ; 20 steps in a
1-2-5 sequence . Variable X1 to X10
magnifier
extends maximum
sweep rate to
20 ns/div .
Accuracy specification applies
over center 8 divisions . Exclude
first
50 ns of sweep for both
magnified and
unmagnified sweep
rates and anything beyond the
100th magnified division .
Within 3% .
Within
5%
.
Within 4% .
Within 6% .
PerformanceRequirement
Approximately 100 mV/div .
Approximately 1
V/div
.
DC to at least 1 MHz with 10 div
reference signal .
DC to least 1 MHz with 5 div
reference signal .
Approximately 1 MO .
Approxiamtely 30 pF .
Approximately 40 pF (front input
only) .
5°
or less from do to 50 kHz .
REV . B, DEC
. 197 6
Frequency
Response
Bandwidth
Dc to at least 15 MHz (5 division
reference signal
centered vertical-
ly from a 25 S2
source with
VOLTS/DIV VAR control
in
calibrated detent) .
Risetime 23 ns
or less .
ChoppedMode Approximately
250 kHz .
Repetition Rate
(T922)
Input Resistance Approximately
1 MO .
Input Capacitance Approximately 30 pF .
(T921 and
T922)
Input Capacitance
(
T922R )
CH 1
and CH 2, Approximately
40 pF .
(front only)
Maximum Input
Voltage
DC Coupled 400 V (dc +
peak ac) .
800 V (p-p ac) at 1 kHz or
less .
AC Coupled 400 V (dc + peak ac) .
800 V (p-p ac) at 1 kHz or less .
Vertical Output
(T922R)
Amplitude
High Im- At
least 0 .5V/div of display .
pedance Load
50 S2 Load Approximately 50 mV/div of dis-
play .
Bandwidth Approximately 1 MHz .

Ch a r acteristic
_
Performance Requirement
REV . B, DEC . 197 6
TABLE
1-1 (cont)
C .
TIME BASE (cont)
TABLE 1-2
Environmental
Characteristic
Altitude
Storage
Operating
Specifications-T921 /T922/T922R
TABLE 1-2 (cont)
PerformanceRequirement
To 50,000 ft .
To 15,000 ft . Maximum operating
temperature decreases 1°C/1,000
ft . above 5,000 ft .
TABLE 1-3
Physical
Triggering
Sensitivity 0 .5 div internal or 100 mV external
from 2 Hz to 1 MHz, increasing to
1 .5 div internal or 150
mV external
at 15
MHz .
TV Sync
Composite sync 1 div internal or
100 mV external (approximately
2 .3 div or 230 mV of composite
video) .
External Trigger Input
Maximum Input 400 V (dc + peak ac) .
Voltage 800 V (p-p ac) (1 kHz or less) .
Input Resistance Approximately 1 Mfg .
Input Capacitance Approximately 30 pF .
(T921 and T922)
Input Capacitance Approximately 40 pF
.
(T922R, front only)
Level Range
EXT +0 .5 V to -0 .5 V .
EXT +5 V to - 5 V .
10
Characteristic PerformanceRequirement
Weight
T921 and T922
With Panel 15 .5 Ibs (7 .0 kg) .
Cover,
Accessories
and
Accessory
Pouch
Without Panel 15 .0 lbs . (6 .8 kg) .
Cover,
Accessories
and Accessory
Pouch
T922R
Without 19 .0 Ibs (8 .6
kg) .
Accessories
Domestic 33 .0 Ibs (15 .0 kg) .
Shipping Wt
Overall
Dimensions
(T921 and T922)
Refer to Fig . 1-3 .
Overall Dimensions
(T922R) Refer to Fig . 1-2 .
Characteristic
Temperature
Storage
Performance Requirement
-55 0 C to +75 0 C .
Operating
T921 & T922
0° C to
+45° C .
T922R 0° C to
+50° C .

Specifications-T921 /T922/T922R
Fig . 1-2 . T922R dimensional drawing .
REV .
B, DEC . 197 6

Fig . 1-3 .
T921/T92 2 dimensional
drawing .
STANDARD
ACCESSORIES
Specifications-T921 /T922/T922R
REV . A, JUNE 1976

1-5
1 Instruction Manual
070-1982-01
1 Probe (T921)
010-0160-00
2 Probes
(T922) 010-0160-00

Specifications-T921 /T922/T922R
The following
accessories have been selected from
our catalog specifically for
your instrument . They
are listed as a convenience to help
you meet your
measurement needs . For detailed information
and
prices,
refer to a Tektronix Products
Catalog or
contact your local Tektronix Field Representative .
COVERS
FRONT COVER : Protects the instrument
front panel
during transport
or storage and provides storage
forsmall
accessories
(probes, cables, etc .) Made of blue plastic to
match the instrument
case .
Order
. . . ..................... . . 016-0340-00
PROTECTIVE WATERPROOF COVER :
Blue vinyl
cover provides
protection for the entire
oscilloscope
during transport
or storage .
Order
.................... ... . . .
016-0361-00
STAND
RECOMMENDED
ACCESSORIES
NOTE
PORTABLE STAND : The Portable
Stand sits on the
floor
and holds the instrument at an angle to provide easy
viewing and
access . Also provides storage for small
accessories (probe, cables,
etc .) .
Order ................. ..........
. . . . . 209
PROBES
P6101 GENERALPURPOSE 1X VOLTAGE PROBE :
Input capacitance
54 picofarads (plus oscilloscope input
capacitance) .
Order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.010-6101-03
P6062A SWITCHABLE 1X-10X
VOLTAGE PROBE :
Provides full bandwidth capabilities of
T900-series in-
struments . Can be compensated
to match the vertical
input
capacitance .
Order ................ .........
.010-6062-13
P6009
GENERAL PURPOSE 100X
VOLTAGE PROBE :
Provides full
bandwidth capabilities of
T900-series in-
struments . Can be
compensated to match the
vertical
input
capacitance .
Order ................. ....... ..
010-0264-01
P6015 GENERAL
PURPOSE 1000X VOLTAGE PROBE :
Provides full bandwidth capabilities of
T900-series in-
struments
. Can be compensated to match
the vertical
input
capacitance .
Order ............ ..............
010-0172-00
P6021 AC CURRENT PROBE : Provides a
bandwidth
from 120
Hz to the upper bandwidth
of T900-series
instruments .
Spring-loaded slide opens (up to 0
.150
inches) to allow
measurement of current without breaking
the circuit under test .
Order ................. ........
.015-0140-02
P6006 GENERAL
PURPOSE 10X VOLTAGEPROBE
:
The P6006 is a 10X do to 35 MHz
voltage probe . The
compensation range of the P6006
allows adjustment to
match
the front inputs of the T922R . The
do to 35 MHz
bandwidth of the
P6006 allows full use of the dc to 15 MHz
bandwidth of the T922R .
Order
....... . ... ............... 010-0160-00
CAMERAS
C-5A Option 3 Camera
: Provides graticule illumination
with
xenon flash lamp powered
by two AA penlight
batteries
. Recommended for, and
molded to fit all bench
version
T900-series instruments . Fixed focus, fixed
aper-
ture f/16 lens with
0 .67 or 0 .85 user
adjustable magnifica-
tion . Mechanical shutter
with speeds of 1/5 to 1/25
s, plus
bulb and time .
Order
..... ... . . .............. C-5A Option 3
C-5A Option 1 Camera
: Recommeded for use with the
T922R
. Option 1 deletes the
graticule flash unit from C5A .
The
T922R is equipped with scale
illumination, so the
graticule flash
unit is not necessary .
The
following cameras are
also compatible with the
T922R using the listed adapter .
RACKMOUNT HARDWARE
KIT
Provides the slides and hardware
needed to mount the
T922R in a
rack .
Order
........... ... . . ......... .
016-0375-00
REV . C JUL 197 7
CAMERA
ADAPTER
C12, Order
. . . . ... ............... 01,6-0299-00
C27, Order
....... ............... 016-0249-03
C30A,Order
........ . .... ..... . . . 016-0248-00
C59, Order
.....................
. 016-0249-03

The T921, T922, and T922R will operate
from either a
120
V
or
240
Vac, 50 to
60 Hz nominal power input source .
To
avoid equipmentdamage, the power input range
selector switch (120 V or 240 V) and HI/LO switch on the
bottom of the instrument (T921/T922 only) mustbe set to
positions which include the value of the applied power
input voltage . The POWER indicator lamp will
blink when
the applied power
input voltage varies more than about
10% from the value for which the switches are set .
To avoid electric shock and equipmentdamage, do
not attempt to change the power input range
selector
switch, HI1LO switch, or internal fuse . This
must
be done by qualified service personnel only .
The T921, T922, and T922R operate from a single-
phase power source with one of the current-carrying
conductors (the neutral conductor) at ground (earth)
potential .
Operation
from power
sources
where both
current-carrying conductors are live with respect to
ground (such as phase-to-phase on a 3-wire system) is not
recommended, since only the line conductorhas over-
current (fuse) protection within the instrument .
The T921, T922, and T922R have a 3-wire cord with a 3-
terminal polarized plug for connection to the power
source and safety-earth . The ground terminal of the plug
is directly connected to the metal parts of the instrument
.
For
electric-shock protection, insert this plug in a
mating
outlet with a safety-earth contact .
FUNCTIONS
OF CONTROLS,
CONNECTORS, AND INDICATORS
T921 AND T922
(See text preceding FIRST TIME OPERATION for
features found only in T922R or those which differ
from the T921/T922 .)
Before you turn the instrument on, read this portion of the
manual
to
familiarize
yourself
with the
controls,
connec-
tors, and indicators .
REV . A, JUNE 1976
OPERATING INSTRUCTIONS
OPERATING VOLTAGE
WARNING
SAFETY INFORMATION
NOTE
Front Panel
(Fig . 2-1)
Section 2-T921 /T922/T922R
A . DISPLAY
INTENSITY-Adjusts the brightness of the crt dis-
play . Set for the lowest visible display to prolong
crt
life .
FOCUS-Adjusts for optimum spot
size and defini-
tion .
( 3 )BEAM FINDER--Locates
off-screen displays . Com-
presses the crt display to
within the graticule area
independently of
the position control or applied
signals .
To locate an off-screen display :
a . Set the vertical
POSITION and INTENSITY
controls to
midrange and rotate the horizontal
POSITION control clockwise .
b . If a display or dot
still
is
not visible, press
BEAM FINDER and
hold in . A compressed dis-
play or dot
should appear . If not, increase
the
INTENSITY until a display appears .
If a dotor vertical line appears,
the sweep is not
triggered . Set the
trigger MODE switch to AUTO
to obtain a
display . Use the vertical and horizontal
POSITION controls to move the display near the
center of the graticule . Release the
BEAM
FINDER button and adjust
the trigger level con-
trol for a stable
display .
If a compressed display appears, adjust the
VOLTS/DIV switch and the horizontal
and ver-
tical POSITION controls for a
stable display .
0
PROBE ADJ-Provides a square-wave output of
approximately 0 .5 V (negative-going with
respect to
ground) at approximately
1 kHz, for compensating
voltage probes .
ON-OFF-Push-push switch turns the instrument
power on (button in) and off (button
out) . (In some
versions this switch is
labeled POWER .)

Operating Instructions-T921/T922/T922R
2-2
POWER-Indicator lamp lights when
ON-OFF but-
ton is
depressed to ON (in) position and
applied
power input voltage
does not vary more than about
10% from thevalue indicated
by the 120 V/240 V and
HI/LO voltage selector
switch settings . When
applied power input voltage varies
more than about
10% (either high or low) from the
selected value, the
lamp will blink .
(In someversionsthis lamp is
labeled
ON .)
O Internal graticule-Eliminates
parallax . Risetime
amplitude and measurement points are indicated at
the left edge of the graticule .
Fig . 2-1 . Display front panel controls and connectors .
Rear Panel
(Fig . 2-2)
Left Side of
Cabinet-T921/T922 only (See Fig . 2-3)
O
ASTIG-Screwdriver adjustment used with FOCUS
control to obtain a well-defined display . Requires
little or no adjustment once
set .
EXT
Z AXIS INPUT-BNC connector for applying
signals to intensity modulate the crt display . Signals
'must be time-related to the display for a stable
display .
TR ROT-Trace rotation
screwdriver adjustment .
Aligns
trace
with the horizontal graticule lines .
REV . A, JUNE 1976

Fig
.
2-2 . Rear panel controls and connectors .
Bottom of Cabinet-T921/T922 only (see Fig . 2-4)
@
120 V/240 V-Screwdriver actuated switch
selects
either 120 V or 240
V nominal power input voltage .
WARNING
To avoid electric
shock and equipment damage, do
not attempt to replace the infernal fuse or change
the
settings of the
power input range selector switch or
HI1LO switch . This must be done by qualified service
personnel only .
@
HI/LO-Screwdriver actuated switch selects either
high or low nominal
power-input-voltage regulating
range : LO selects 100 V or 220 V and HI selects
120 V or 240 V .
REV . B APR 1977
Operating Instructions-T921/T922/T922R
@
CH 1 DC BAL-Screwdriver adjustment
. When
properly adjusted,
prevents trace shift when
switching between
adjacent positions of the CH 1
VOLTS/DIV
switch .
CH 2 DC BAL-Screwdriver
adjustment . When
properly adjusted,
prevents trace shift when
switching between
adjacent positions of the CH 2
VOLTS/DIV switch .
FrontPanel (Fig . 2-5)
B . VERTICAL AMPLIFIER
O
VOLTS/DIV-Selects the vertical
deflection factor in
a 1-2-5 sequence
(VAR control must be in detent
position
to obtain the indicated deflection factors) .
Read the correct deflection factor for a 1X probe
from the 1X position and a 10X probe
from the 10X
position .
O
VAR-Provides continuously variable
uncalibrated
deflection factors between the
calibrated steps of
the VOLTS/DIV switches .
Extends the maximum
deflection factor to 25
V/div in the 10 V position .
Detent
position provides calibrated
VOLTS/DIV
deflection factors .
Input Coupling-Selects
the method of coupling the
input
signal to the vertical input signal
amplifier .
AC :
Signals are coupled
capacitively . Any do
signal component is blocked .
Low frequencies
are attenuated (3 dB
down at about 1 Hz using a
10X probe) . Ac
coupling causes tilting of square
wavesbelow
about 1 kHz .
GND :
Grounds the input of the vertical
amplifier
to provide a ground reference
display . Connects
the input signal to
ground through the input
coupling capacitor
and a 1 Mil resistor to allow
the input coupling
capacitor to be precharged
by
the input signal .
DC : All components
of the input signal are
passed to
the vertical amplifier .
Channel 1 or Y Input-Connector
for applying an
external signal to the vertical
deflection system .
Provides the Y input in the
X-Y mode when CH 1
vertical mode button
is in .
O
Channel 2 Input-Connector for
applying an exter-
nal signal to the vertical deflection
system .
2-3

Operating Instructions-T921/T922/T922R
2-4
Fig . 2-3 . Left side of cabinet .
1982-32
Fig . 2-4 . Bottom of cabinet .
REV . B APR 1977
12
say
U
~ ~II III II III
U
WARNING
WOMM
- S
settings of the power input range selector switch
or
HI1LO switch . This must be doneby qualified service
personnel only .
19 82-37

og
\O6
VOLTS/DIV
TRACE CH 2
PRO

PROBE
' w m
AC /S
GRD~~
DC
N
POSITION
S
(CHI
TRIG)
FA 0
VOLTS/DIV
Ix

tox
PROBE 1 , z
PROBE
S
AC
~t75
GOOD
RAO 30DF
\ W
DC
AMPLIFIER
t
1982-11A
O POSITION-Controls the vertical position
of
the crt
display .
O Vertical Mode-Selects the vertical amplifier
operating mode .
CH 1 : Displays only signal applied to the CH 1
input connector . This button mustbe latched in
for X-Y operation .
CH 2 : Displays only signal applied to the
CH 2
input connector .
DUAL TRACE : Displays CH 1 and
CH
2 input
signals alternately . Chop or Alternate mode is
selected automatically by the SEC/DIV switch .
For SEC/DIV switch settings
of 1 ms and slower,
Chop is selected . For settings
of .5 ms and
faster,
Alternate is selected . In DUAL TRACE mode, the
trigger signal is derived from CH 1 . When the
DUAL TRACE
and CH 2 buttons are locked in at
the same time, the trigger signal
comes from CH 2
(instead of CH 1) while DUAL TRACE signals are
displayed .
REV . A, JUNE 1976
Fig . 2-5 . Vertical amplifier front panel controls .
Operating Instructions-T921/T922/T922R
Front Panel (Fig . 2-6)
C .
TIME BASE
SOURCE-Selects the source of the trigger signal
.
INT : Uses a sample of the signal displayed on
the crt as a trigger signal in the CH 1 or CH 2
modes . In DUAL TRACE mode, the trigger signal
is obtained from CH 1 . If CH 2and
DUALTRACE
buttons are both latched in,
channel 2 is the
trigger source .
Line :

Uses a
sample
of
the power-line frequency
as a
trigger signal .
EXT :

Permits triggering on
signals applied to the
X (external trigger) input connector . External
trigger signals must be time-related to the
dis-
played signal for a stable display .
EXT=10 : External trigger
signal is attenuated by a
factor of 10
.
X-Y : Permits x-y display . X (horizontal) input is
through the X input connector . Y (vertical)
input
is normally through the CH 1
orY input connector
(vertical mode CH 1 button must be latched in) .
For special applications, the Y input may be
obtained from the CH 2 input connector (CH 2
button latched in), or from both CH
1 and CH 2
(DUAL TRACE button latched
in) .
tx tox CH 1 DUAL
2-5

Operating
Instructions-T921/T922/T922R
2-6
I
L I MODE-Selects the operating
mode for the trigger
circuit .
AUTO : With the
proper LEVEL control setting,
the sweep can be triggered
by trigger signals with
repetition rates above about
20 Hz . In the
absence of an adequate trigger signal, or when
the LEVEL
control is misadjusted, the sweep free
runs to provide a reference display .
NORM : Permits triggering
on displayed signal .
In the absence of an adequate
trigger signal, or
when the LEVEL control is misadjusted, the
sweep does not run and no display is visible .
Setting
SOURCE to LINE position provides an
adequate trigger signal .
TV : Permits
triggering on television signals .
Triggers on TV field whenSEC/DIV
switch is set
at .1 ms or slower . Triggers
on TV line when
SEC/DIV switch is set at
50 Ns or faster . Set the
SLOPE switch to +OUT for sync-positive input
signals and to -IN for sync-negative
input
signals .
(SLOPE-Selects the
positive- or negative-going
slope of the trigger
waveform
.
+OUT :
The sweep can be triggered from the
positive-going portion
of a trigger signal .
Fig . 2-6 . Time base front panel controls and connectors .
-IN : The sweep can be triggered from the
negative-going portion of a trigger signal .
LEVEL-Selects the amplitude
point on the trigger
signal at which the sweep is triggered .
Usually
adjusted for the desired display after trigger
SOURCE and
SLOPE have been selected .
(X (External Trigger)-Provides input
for external
trigger signals or for X axis signals in the X-Y mode .
SEC/DIV-Selects calibrated sweep
rates in a 1-2-5
sequence . X1-X10
variable control must be in the X1
detent position (fully ccw)
to read calibrated sweep
rates directly from the
SEC/DIV knob . Knob
numerals with
N
underneath indicates
sweep rates in
microseconds/division, numerals
with rn
underneath indicate
sweep rates in millisecon-
ds/division, positions with
no symbol under the
numerals indicate
sweep rates in seconds/division .
X1-X10-Provides calibrated sweep
rates when in X1
(fully ccw) detent position . Increases the
horizontal
gain by a factor of 10, providing at least
20 ns/div
sweep rate in
the X10 detent position (fully cw) with
the SEC/DIV knob set
to .2 /is .
(POSITION-Controls the horizontal
position of the
crt display .
REV . B APR 197 7

FUNCTIONS OF CONTROLS,
CONNECTORS, AND INDICATORS
T922R
The following information
shows the different

O INTENSITY
mechanical layout of
the T922R and discusses features
found only on the rac kmount version . The location and
names of all T922R controls, connectors, and indicators
are given here . For the discussion of
those common to
T921, T922 and
T922R, see the Operating Instuctions
section of the standard T921/T922 portion of this
manual .
REV . A, JUNE
1976
FOCUS
BEAM FIND
vEEN
D
NE L EN
M
LEN 01
0
nom
a
" em
inNNEN

-

A] I .
O
000 -oo~
rn
0 ®®
13
Fig . 2-7 . T922R display controls, connectors, and indicators .
Operating Instructions-T921/T922/T922R
A . DISPLAY
(FIG . 2-7)
1982-47
2-7

Operating Instructions-T921/T922/T922R
PROBE ADJ
(DOFF-ON
O
POWER Lamp
0
Internal Graticule
(8
) Z AXIS IN
OASTIG
0
TRACE ROT
@1@1@1
and
are internally
accessible only
.
To avoid electric shock and
equipmentdamage, do
not attempt to change the power input range
selector switch, HI1LO switch, or internal fuse . This
must be done
by qualified service personnel only .
@
SCALE ILLUM
AC RMS RANGE-Indicates the
voltage from which
the T922R is set to operate .
O VOLTS/DIV
OVAR
B . VERTICAL AMPLIFIER (FIG . 2-8)
O
Input Coupling
2-8
-In the T922R these controls
WARNING
O Channel 1 or Y Inputs-Two switch-selectable in-
puts for
applying signals to Channel 1 . One is
mounted on the front panel and the other on the rear
panel .
(DChannel 2 Inputs-Two switch-selectable inputs for
applying signals to Channel 2 . One
is mounted on
the front panel and the other on the rear panel .
OPOSITION
O
Vertical Mode-When operating in the DUAL
TRACE
mode you must manually select either
CHOP or ALT (see control
8) .
O
CHOP-ALT-Selects either CHOP
or
ALT
dual trace
modes . Use CHOP at lower sweep speeds and ALT
at
higher
sweep speeds .
O COMP VERT SIG OUT-The signal available
at this
connector is a sample of the vertical signal being
displayed plus a do component proportional to the
the
vertical position of the display .
FRONT-REAR-Two push-button switches, one for
CH 1 and one for CH 2, which select either the front
or the rear vertical inputs .
O SOURCE
O
MODE-To use the AUTO, NORM,
or
TV
SYNC
modes the SINGLESWEEP/REPETITIVE button
mustbe set to REPETITIVE (out) .
SLOPE
O
LEVEL
O
SEC/DIV
X1-X10
POSITION
C . TIME BASE (FIG .
2-9)
(D
EXT TRIG or
X-Two
switch-selectable
inputs for
external
trigger
or
X
axis
signals
.
One is mounted on
the front panel and the other on the rear panel .
REV . A, JUNE 1976