Tektronix 7844 User manual

Tektronix
COMMITTED TO EXCELLENCE
PLEASE CHECK FOR CHANGE INFORMATION
AT THE REAR OF THIS MANUAL.
7844/R7844
DUAL-BEAM
OSCILLOSCOPE
WITH OPTIONS
OPERATOR
INSTRUCTION MANUAL
Tektronix, Inc.
P.O. Box 500
Beaverton, Oregon 97077 Serial Number
070-1675-00 First Printing AUG 1974
Product Group Revised NOV 1981

a
Copyright © 1974 Tektronix, Inc. All rights reserved.
Contents of this publication may not be reproduced in any
form without the written permission of Tektronix, Inc.
Products of Tektronix, inc. and its subsidiaries are covered
by U.S. and foreign patents and/or pending patents.
TEKTRONIX, TEK, SCOPE-MOBILE, and are
registered trademarks of Tektronix, Inc. TELEQUIPMENT
is a registered trademark of Tektronix U.K. Limited.
Printed in U.S.A. Specification and price change privileges
are reserved.
INSTRUMENT SERIAL NUMBERS
Each instrument has a serial number on a parel insert, tag,
or stamped on the chassis. The first number or letter
designates the country of manufacture. The last five digits
of the serial number are assigned sequentially and are
unique to each instrument. Those manufactured in the
United States have six unique digits. The country of
manufacture is identified as follows:
B000000 Tektronix, Inc., Beaverton, Oregon, USA
100000 Tektronix Guernsey, Ltd., Channel Islands
200000 Tektronix United Kingdom, Ltd., London
300000 Sony/Tektronix, Japan
700000 Tektronix Holland, NV, Heerenveen,
The Netherlands

7844/R7844 Operators
TABLE OF CONTENTS
PAGE
List
of
illustrations
iti
List
of
Tables
ili
SECTION 7 OPERATING INSTRUCTIONS
FEATURES
1-1
PRELIMINARY
OPERATION
1-1
Safety
Information
1-1
Operating
Voltage
1
Operating
Temperature
1-2
Operating
Position
1-2
PLUG-IN
UNITS
1-2
Installation
of
Plug-In
Units
1-2
CONTROLS
AND
CONNECTORS
1-2
Front-Panel
Color
Coding
1-2
FAMILIARIZATION
PROCEDURE
1-2
Set-Up
Information
1-3
Display
Controls
1-3
Vertical
System
and
Calibrator
7-8
Horizontal
System
1-9
Graticule
and
Readout
Pulsed
Operation
7-10
DETAILED
OPERATING
INFORMATION
1-11
Crt
Display
Intensity
Controls
1-11
Display
Focus
1-17
Trace
Alignment
1-12
Graticule
1-12
Light
Filters
1-12
Graticule
Illumination
4-12
Readout
Display
1-12
Beamfinder
1-13
Control
Hlumination
1-14
Calibrator
Output
1-14
Probe
Power
4-14
Horizontal
Display
Mode
Combinations
1-14
Vertical
Display
Mode
Combinations
1-14
Beam
2
Display
Characteristics
1-14
Amplifier
Unit
Alternate
Operation
1-15

7844/R7844 Operators
TABLE OF CONTENTS (CONT.)
PAGE
SECTION 1 (continued)
Trigger Source 1-15
Intensity Modulation 1-15
Remote Grat/Readout Single Shot 1-15
Single Sweep Input/Output 1-15
Output Signals 1-16
Display Photography 1-16
APPLICATIONS
1-16
Vertical Amplifier Plug-In Units 1-17
Time-Base Plug-In Units 1-17
Sampling Displays 1-17
Special Purpose Plug-In Units 1-18
X-Y¥ Operation 1-18
Raster Display 1-19
SECTION 2 SPECIFICATION
INTRODUCTION
2-1
SYSTEM ELECTRICAL SPECIFICATION 2-9
STANDARD ACCESSORIES 2-12
SECTION3 RACKMOUNTING INSTRUCTIONS
INTRODUCTION 3-1
INSTRUMENT
DIMENSIONS
3-1
RACK DIMENSIONS 3-1
Height 3-1
Width 3-1
Depth 3-1
SLIDE-OUT TRACKS 3-1
MOUNTING PROCEDURE 3-2
REMOVING OR INSTALLING THE INSTRUMENT 3-3
SLIDE-OUT TRACK LUBRICATION 3-3
SECTION4 INSTRUMENT OPTIONS
INTRODUCTION 41
OPTION
3
4-1
OPTION 21 4-7

7844/R7844 Operators
TABLE OF CONTENTS (CONT.)
SECTION 4 (continued)
OPTION 78
OPTION 22
Controls and Connectors
Display Photography
CHANGE INFORMATION
FIGURE NO.
4-1
1-2
4-3
1-4
2-1
3-1
3-2
3-3
3-4
3-5
3-6
4-1
TABLE NO.
2-4
2-2
2-3
2-4
2-5
2-46
4-1
LIST OF ILLUSTRATIONS
Frontispiece
Front-panel controls and connectors.
Rear-panel controls and connectors.
Definition of measurement lines on the 7844/R7844 graticule,
Location of readout display on the crt identifying the originating plug-in and channel.
7844 dimensional drawing.
Stide-out track assembly.
Vertical mounting position of the stationary section and location of the thumb screw
securing hole (left stationary section shown).
Details for mounting stationary sections.
Installing and removing the instrument.
Adjustment of the slide-out tracks for smooth sliding action.
R7844 dimensional drawing.
Location of Readout Mode Switch on the Readout circuit board.
LIST OF TABLES
Electrical
7844/R7844 Oscilloscope System Vertical Specification
7844/R7844 Oscilloscope System Horizontal Specification
Special Purpose and Sampling Plug-in Units
Environmental
Physical
Option Information Locator
PAGE
PAGE
2-4
2-9
2-10
2-10
2-11
2-11
4-3
ili

7844/R7844 Operators
7844 DUAL-BEAM OSCILLOSCOPE
R7844 OPTION 21 DUAL-BEAM OSCILLOSCOPE 1675-12

Section 1-7844/R7844 Operators
OPERATING
INSTRUCTIONS
FEATURES
The Tektronix 7844/R7844 Dual-Beam Oscilloscope is a
solid-state, wide bandwidth, dual-beam oscilloscope. The
instrument accepts Tektronix 7000-Series plug-in units to
form a complete measurement system. The flexibility of
the plug-in feature and variety of plug-in units available
allow the system to be used for many measurement applica-
tions.
The 7844/R7844 provides separate vertical and horizontal
deflection
systems, FOCUS, INTENSITY, and BEAMFIND-
ER functions for each beam. The plug-in unit in either
vertical compartment can be selected to provide vertical de-
flection for either beam. The plug-in units in either horizon-
tal compartment may be selected to provide horizontal de-
flection for either beam.
The
7844/R7844 features regulated de power supplies to
ensure that the performance is not affected by variations in
line voltage and frequency, or by changes in load due to vary-
ing power requirements of the plug-in units. The 7844/R7844
operates from a 115 valt or 230 volt (50 Hz to 400 Hz)
nominal line source.
Other features include a dual-gun full-overlap crt with a
graticule area of 8 x 10 centimeters. The instrument also
provides a crt display of alphanumeric information encoded
by the plug-in units. The READOUT display indicates plug-
in unit status such as deflection factor, sweep rate, and other
plug-in dependent parameters.
The Option 21 instrument is basically the same as the stan-
dard 7844/R7844 except that the vertical deflection system
is dedicated. The amplifier unit in the LEFT VERT compart-
ment controls the vertical deflection of beam 1 and the am-
plifier unit in the RIGHT VERT compartment controls the
vertical deflection of beam 2. The VERTICAL MODE switch
and VERT SEP control have been deleted. Refer to the
Options section for details.
PRELIMINARY OPERATION
To effectively operate this instrument, the user must be-
come familiar with the operation and capabilities of the in-
strument. This section describes how to use the front and
rear-panel controls and connectors.
REV. C JAN 1977
Safety Information
This instruction manual contains warning information which
the user must follow to ensure safe operation of the instru-
ment. Warning information is intended to protect the opera-
tor and Caution information is intended to protect the
instrument.
WARNING }
This instrument is intended to be operated from
a single-phase earth-referenced power source
having one current-carrying conductor {the Neu-
tral Conductor) near earth potential, Operation
from power sources where both current-carry-
ing conductors are live with respect to earth
(such as phase-to-phase on a three-wire system)
is not recommended, since only the Line Con-
ductor has over-current {fuse} protection with-
in the instrument.
This instrument has a three-wire power cord
with a three-terminal polarized plug for connec-
tion to the power source and safety-earth, The
safety-earth terminal of the plug is directly con-
nected to the instrument frame. For electric-
shock protection, insert this plug only in a mat-
ing outlet with a safety-earth contact or other-
wise connect the frame to a safety-earth system.
The color-coding of the cord conductors is in
accordance with recognized standards.
Power Cord Conductor Identification
Conductor Color Alternate Color
Ungrounded (Line) Brown Black
Grounded (Neutral) Blue White
Grounding (Earthing) Green-Yellow Green-Yellow
Operating Voltage
The 7844/R7844 has a VOLTAGE SELECTOR switch which
allows selection of either a 115 volt or 230 volt nominal line
voltage source. When changing the Voltage Selector switch
position, disconnect the power cord and use a small screw-
driver to move the Voltage Selector switch to the desired
range.
1-1

Operating instructions—7844/R7844 Operators
(ey
° CAUTION
PPL LLL PS
Damage to this instrument may occur if the
Voltage Selector switch is set to an incorrect
position for the line voltage applied.
Voltage Selector
Switch Pasition
115 Vv
230 V
Regulating
Range
90 to 132 volts
180 to 264 volts
Operating Temperature
The 7844/R7844 can be operated where the ambient air
temperature is between 0°C and +50°C. After storage at
temperatures beyond the operating limits, allow the chassis
temperature to come within the operating limits before
power is applied.
The 7844 is cooled by air drawn in through holes in the
side and bottom panels and blown out through the fan ex-
haust. To ensure proper cooling of the 7844, maintain the
clearance provided by the feet on the bottom and allow 2
inches clearance on the top, sides, and rear (more clearance,
if possible}. The R7844 is cooled by air drawn in through
the air filter on the rear panel and blown out through holes
located on the side panels. To ensure proper cooling of the
R7844, refer to the dimensional drawing in Section 3 of
this manual (Fig. 3-6).
A thermal cutout disconnects power from this instrument
if the internal temperature exceeds a safe operating level.
Power is automatically restored when the temperature re-
turns to a safe level.
Operating Position
A bail-type stand is mounted on the bottom of the 7844.
This stand permits the instrument to be tilted up about 10°
for more convenient crt viewing.
PLUG-IN UNITS
The 7844/R7844 accepts up to 4 Tektronix 7000-Series
plug-in units. This feature allows selection of bandwidth,
sensitivity, display mode, etc., and provides for future ex-
pansion of the system.
The overall capabilities of the system are determined mainly
by the characteristics of the plug-ins selected. Some typical
combinations are given under Applications, in this manual,
along with simplified set-up instructions, For information
on other plug-in units, refer to the current Tektronix catalog.
installation of Plug-In Units
Plug-in units can be installed or removed without turning
the instrument power off. To install a plug-in unit into a
compartment, align the slots in the top and bottom of the
plug-in unit with the associated guide rails in the plug-in
compartment. Insert the plug-in unit into the compartment
until it locks into place. To remove a plug-in unit, pull the
release latch on the plug-in unit to disengage it. To meet
emi specifications, all unused plug-in compartments should
be covered with an emi-shielded, blank plug-in panel, Tek-
tronix Part 016-0155-00.
The 7844/R7844 Calibration procedure given in the Service
manual normalizes the vertical and horizontal gains. This
allows plug-in units to be interchanged between plug-in com-
partments without recalibration. The basic calibration of
the plug-in units should be checked when installed to verify
their accuracy (refer to plug-in operating instructions}.
CONTROLS AND CONNECTORS
Figure 1-1 and Figure 1-2 show the front and rear panels. A
brief description of each contro! and connector is given. Re- a
fer to Detailed Operating Information in this manual for
additional operating information.
Front-Panel Color Coding
Portions of the 7844/R7844 front-panel are color-coded.
These color-coded areas are defined by their functions. Red
identifies the nomenclature and controls that will uncalibrate
the instrument. Biue identifies the controls affecting the
crt display mode. Green identifies all trigger controls.
Other colors such as gray, orange and yellow, have no func-
tional assignments, but are used as needed to indicate the
relationship between controls and/or connectors.
FAMILIARIZATION PROCEDURE
The following procedure may be used for familiarization
with the 7844/R7844 or as a check of basic instrument op-
eration. ff performing the Familiarization Procedure reveals
improper calibration or instrument malfunction, first check
the operation of the associated plug-in units; then refer to
the Calibration and Maintenance sections of the 7844/R7844
Service manual.

Set-up information for both the standard 7844/R7844 and
Option 21 precedes each major section of this Familiariza-
tion Procedure, The control settings for plug-in units and
signal connections, when needed, are also given.
Set-Up Information
Set front-panel controls as follows:
POWER switch Off
CALIBRATOR (4 kHz)
READOUT INTENSITY OFF
EXT/BEAM 2 GATED BEAM 2 GATED
{push button OUT}
GRAT ILLUM
wise
EXT/BEAM 2 GATED BEAM 2 GATED
(push button OUT}
A TRIG SOURCE LEFT
B TRIG SOURCE RIGHT
BEAM 1
INTENSITY Midrange
FOCUS Midrange
VERTICAL MODE LEFT
BEAMFINDER Push button out
HORIZONTAL MODE A
HORIZ SEP (1) Midrange
BEAM 2
INTENSITY Midrange
FOCUS Midrange
VERTICAL MODE RIGHT
BEAMFINDER Push butten out
HORIZONTAL MODE B
4 V push button in
Fully counterclock-
Operating instructions—7844/R7844 Operators
1. Connect the 7844/R7844 to a power source that meets
the voltage and frequency requirements of the instrument.
lf the available line voltage is outside the limits of the Vol-
tage Selector, see Operating Voltage discussion in this section.
2. Install Tektronix 7A-Series amplifier units into both the
LEFT VERT and RIGHT VERT compartments. Install Tek-
tronix 7B-Series time-base units into the A and B HORIZ
compartments.
3. Turn the POWER switch ON.
4, Connect the 4 V CALIBRATOR output to the left and
right vertical plug-in units with a BNC cable and a dual in-
put coupler.
5, Set the deflection factors of both vertical units for 2
divisions of displayed signal and center the position controls,
Set both units for de input coupling.
6. Set both time-base units for a sweep rate of 1 millisecond/
division, Set the triggering for auto mode with ac coupling
from the internal source and the level control for a stable
display. Position the display as necessary.
Display Controls
7. Rotate the BEAM 1 and BEAM 2 INTENSITY controls
throughout their ranges; then set the INTENSITY controls
to a desired viewing level.
8. Set the BEAM 1 FOCUS control so that the top and bot-
tom portions of the beam 1 display are as thin as possible
but not elongated. Set the BEAM 2 FOCUS contro! so that
the top and bottom portions of the beam 2 display are as
thin as possible but not elongated.
NOTE
This instrument contains circuitry to automati-
cally protect the crt against damage due to ex-
cessive crt beam current, If the INTENSITY
control is set to a point where ert phosphor
damage could occur, this circuit limits the beam
current to a safe level. The circuit action will
also cause the trace to defocus which indicates
that the intensity should be reduced. There-
fore, if the FOCUS adjustment cannot be satis-
factorily made, reduce the INTENSITY and
repeat
step 8.
4-3

Operating Instructions—-7844/R7844 Operators
Fig. 1-1. Front-panel controls and connectors.
1-4
1675-9