Tektronix 7B87 User manual

Tektronix, Inc.
P.O. Box 500
Beaverton, Oregon
070-2788-00
Product Group 42
Tektronix:
COMMITTED TO EXCELLENCE
PLEASE CHECK FOR CHANGE INFORMATION
AT THE REAR OF THIS MANUAL.
7B87
TIME BASE
WITH
PRETRIGGER
ACQUIRE CLOCK
INSTRUCTION MANUAL
97077 Serial Number —
First Printing APR 1980
Revised JAN 1986

Copyright © 1980 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 pariel 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

7B87 Instruction
TABLE OF CONTENTS
PAGE
UST OF ILLUSTRATIONS ..
LIST OF TABLES ........
OPERATORS SAFETY SUMMARY
SERVICING SAFETY SUMMARY .
SECTION 1—-OPERATING INSTRUCTIONS
INSTALLATION .
CONTROLS, CONNECTORS, AND INDICATORS
FUNCTIONAL CHECK ..
SETUP PROCEDURE
SWEEP FUNCTIONS...
TRIGGERING FUNCTIONS
PRETRIGGER ACQUIRE CLOCK FUNCTIONS
GENERAL OPERATING INFORMATION
TRIGGERING SWITCH LOGIC .
TRIGGERING MODES
TRIGGER COUPLING .
TRIGGER SOURCE .
TRIGGER SLOPE .
TRIGGER LEVEL .
HORIZONTAL SWEEP RATES .
TIME MEASUREMENT.......
SWEEP MAGNIFICATION .
VARIABLE HOLD OFF .. tee *
MAINFRAME OPERATING MODES . 1-12
APPLICATIONS .......+--200eee ees
TIME INTERVAL MEASUREMENTS . a
PERIOD AND FREQUENCY MEASUREMENTS ...
RISE-TIME AND FALL-TIME MEASUREMENTS
PULSE WIDTH MEASUREMENTS...............
CORDOHEES
HHS
SECTION 2--SPECIFICATION
STANDARD ACCESSORIES ......
[wannine )
THE REMAINING PORTION OF THIS TABLE OF CONTENTS
LISTS SERVICING INSTRUCTIONS. THESE SERVICING
INSTRUCTIONS ARE FOR USE BY QUALIFIED PERSONNEL
ONLY. TO AVOID ELECTRICAL SHOCK, DO NOT PERFORM
ANY SERVICING OTHER THAN THAT CALLED OUT IN THE
OPERATING INSTRUCTIONS UNLESS QUALIFIED TO DO
so.
SECTION 3--THEORY OF OPERATION
BLOCK DIAGRAM DESCRIPTION
TRIGGER GENERATOR ....
SWEEP GENERATOR
PICKOFF AMPLIFIER AND DELAY GATE
DIGITAL VOLTMETER .
CLOCK GENERATOR ..
REV JUN 1981
DETAILED CIRCUIT DESCRIPTION ..
FRONT-PANEL DISTRIBUTION
TRIGGER GENERATOR ..
EXTERNAL SOURCE.
INTERNAL AND LINE SOURCE
TRIGGER SOURCE SELECTOR AND
AMPLIFIER ...
PEAK-TO-PEAK AUTO.
SLOPE
SELECTOR AND TRIGGER
GENERATOR .
GATE GENERATOR
SSSI
Oooo
SWEEP MODES
HOLD OFF TIMING . +
LOCKOUT BUFFER AMPLIFIER .
HOLD OFF OUTPUT AMPLIFIER.
SWEEP GENERATOR.........
TIMING CURRENT SOURCE
RAMP GENERATOR .......
HORIZONTAL PREAMPLIFIER
SWEEP GATE GENERATOR . z
DVM occ vcscccescectecceescencetoccoeeressoeseee 3-10
DELAY TIME COMPARATOR AND DELAY
GATE GENERATOR
DIGITAL VOLTMETER .
DELAY COMPARISON VOLTAGE-TO-RAMP
CONVERTER
COMPARATOR
REFERENCE CURRENT SOURCE .
REFERENCE CURRENT INVERTER
COUNTER AND ENCODER .
CLOCK GENERATOR
CONTROL LOGIC
OSCILLATOR ..
FIRST DIVIDER .
X1-X10 MULTIPI
DECADE DIVIDER .
INTERNAL CLOCK MULTIPLEXER
OUTPUT CLOCK MULTIPLEXER
INTENSIFY CIRCUIT
7887 IN A HORIZ PLUG-IN COMPARTMENT “
INTERNAL BUTTON PRESSED......
7887 IN B HORIZ PLUG-IN COMPARTMENT .
INTERNAL BUTTON PRESSED..........
TIME/DIVISION AND READOUT SWITCHING .
BASIC READOUT SYSTEM .
TIME/DIVISION READOUT.
ACQUIRE-STOP DELAY TIME READOUT
INTERFACE CONNECTIONS AND POWER
SUPPLY ciivesedccececseveeevevessses asesee S47
SECTION 4-—-MAINTENANCE
PREVENTIVE MAINTENANCE ...
CLEANING....
EXTERIOR ....
INTERIOR...
SWITCH CONTACTS

TROUBLESHOOTING ........
CORRECTIVE MAINTENANCE ......
ADJUSTMENT AFTER REPAIR
7B87 Instruction
TABLE OF CONTENTS (CONT)
VISUAL
INSPECTION . 41
LUBRICATION a 41
CAM SWITCH LUBRICATION. 4-2
SEMICONDUCTOR CHECKS .. wesses MEQ
ADJUSTMENT AFTER REPAIR
TROUBLESHOOTING AIDS 4-2
DIAGRAMS . 42
VOLTAGES AND WAVEFORMS. * 4-2
CIRCUIT-BOARD ILLUSTRATIONS ... 4-2
SWITCH CAM IDENTIFICATION .. 44
DIODE COLOR CODE..
WIRING COLOR CODE oe
SEMICONDUCTOR LEAD CONFIGURATIONS .....
INTER-BOARD PIN CONNECTOR
IDENTIFICATION
MULTI-PIN CONNECTOR IDENTIFICATION .
INTERFACE CONNECTOR PIN LOCATIONS .
PERFORMANCE CHECK AND ADJUSTMENT .
STATIC SENSITIVE DEVICES ....
TROUBLESHOOTING EQUIPMENT.....
TROUBLESHOOTING TECHNIQUES.....
TROUBLESHOOTING PROCEDURE .
OBTAINING REPLACEABLE PARTS ..
SOLDERING TECHNIQUES........ 5 z
COMPONENT REMOVAL AND REPLACEMENT
CIRCUIT BOARDS
SWITCHES
SEMICONDUCTORS .
INTERCONNECTING PINS.
CIRCUIT-BOARD PINS .
FRONT-PANEL LIGHTS ..
INSTRUMENT REPACKAGING .
PAGE
SECTION 5--PERFORMANCE CHECK AND
ADJUSTMENT
PRELIMINARY INFORMATION
ADJUSTMENT INTERVAL .
TEKTRONIX FIELD SERVICE.
USING THIS PROCEDURE
TEST EQUIPMENT REQUIRED . .
SPECIAL FIXTURES
TEST EQUIPMENT ALTERNATIVES.
INDEX TO PERFORMANCE CHECK AND
ADJUSTMENT PROCEDURE ..
PRELIMINARY PROCEDURE
A. TRIGGERING SYSTEM ...
B. HORIZONTAL/AQS SYSTEM .
SECTION 6—!INSTRUMENT OPTIONS
SECTION 7 REPLACEABLE ELECTRICAL PARTS
SECTION 8--DIAGRAMS AND CIRCUIT BOARD
ILLUSTRATIONS
SECTION 9—REPLACEABLE MECHANICAL PARTS
CHANGE INFORMATION
REV JUN 1981

FIG.
NO.
Frontis.
piece
1-
1
1
iF
3
4
No
1
2
7B87 Instruction
LIST OF ILLUSTRATIONS
PAGE
7887 Features........
Location of release latch.
Front-panel controls, connectors, and
INDIO wi vcs sssansuese ees earcceanes 1-2
Single Sweep Acquisition.........6.-066s000e005 15
Effect of LEVEL control and SLOPE switch
on crt display
Area of graticule used for most accurate
time measurements
Operation of sweep magnifier
Measuring the period and determining the
frequency of a displayed waveform ............. 1-13
Measuring the rise time and fall time of
a displayed waveform ...........0000seseeeees 1.14
Measuring the pulse width of a displayed
waveform
7887 dimensional drawing
Basic block diagram of the 7887 Delaying
Time Base Unit
Detailed block diagram of Trigger Generator
Timing diagram for Gate Generator stage
(292, 096, 98)
Detailed block diagram of Logic circuit .
Detailed block diagram of Sweep Generator .
Timing of events that form the Delay
Gate signal
Lubrication procedure for a typical
CAM SWICH wicks cuovuvcri macevacsansaveseroavee
Semiconductor lead configuration
Inter-board multi-pin connector assembly .
REV JUN 1981
FIG.
PAGE
NO.
44 End-lead multi-pin connector assembly .......... 44
45 Location of pin numbers on Interface
connector
4-6 7887 troubleshooting chart .
47 Readout board removal procedure ..
48 Coaxial end-lead connector assembly .
49 Location of securing screws and inter-board
multi-pin connectors on clock circuit board. ..... 4-12
4-10 Cam switch removal procedure ..........0-45+5 4-13
Removal procedure for typical pushbutton
switch
4-12 Exploded view of circuit-board pin and
ferrule
The illustrations in Section 8 are located near their associated
diagrams on the foldout pages.
1 Semiconductor Lead Configurations
2 Locations of circuit boards in the 7B87.
3 A2-Trigger circuit board assembly
4 A1-Interface circuit board assembly
5 A1-Interface circuit board assembly
-6 A1-Interface circuit board assembly
7 A4-Clock circuit board assembly
8 A4-Clock circuit board assembly.
3 A3-Readout circuit board assembly,
1 A1-Interface circuit board assembly
1 Test Point and Adjustment Locations =o

7887 Instruction
LIST OF TABLES
PAGE
TIME/DIV Setting Relationship To 7887
Internal Acquire Clock Rep Rate .
Electrical Characteristics .
Mainframe Horizontal Compatibility
Environmental Characteristics .... ae
Physical Characteristics ............00eeeeee eee
Truth Table, TIME/DIV Setting vs. Strobes
for U637 and U63B oo... ee eeeeeeeeeeeee eens
Selected Inputs or X1 and X10 Multiplexers.
Operation of Output Multiplexer U655 ...
Current in CH1 Readout Line vs. Acquire
Clock Mode, During TS10. ..
Readout Character Selection
Relative Susceptibility .
Test Equipment .....
Acquire Clock Repetition Rate Output.
Delay Time Linearity
Acquire-Stop Delay Accuracy . 6-13
Sweep Timing .
Magnified Sweep Timing .

7887 Instruction
OPERATORS SAFETY SUMMARY
The general safety information in this part of the summary is for both operating and servicing personnel. Specific
warnings and cautions will be found throughout the manual where they apply, but may not appear in this summary.
TERMS
IN THIS MANUAL
CAUTION statements identify conditions or practices that could result in damage to the equipment or other property.
WARNING statements identify conditions or practices that could result in personal injury or loss of life.
AS MARKED ON EQUIPMENT
CAUTION indicates a personal injury hazard not immediately accessible as one reads the marking, or a hazard to
property including the equipment itself.
DANGER indicates a personal injury hazard immediately accessible as one reads the marking.
SYMBOLS
IN THIS MANUAL
® Static-Sensitive Devces.
A This symbol indicates where applicable cautionary or other information is to be found.
AS MARKED ON EQUIPMENT
4 DANGER—High voltage.
© Protective ground (earth) terminal.
A ATTENTION—refer to manual
WARNINGS
POWER SOURCE
This product is intended to operate in a mainframe connected to a power source that will not apply more than 250 volts
rms between the supply conductors or between either supply conductor and ground. A protective ground connection by
way of the grounding conductor in the mainframe power cord is essential for safe operation.
GROUNDING THE PRODUCT
This product is grounded through the grounding conductor of the mainframe power cord. To avoid electrical shock, plug
the mainframe power cord into a properly wired receptacle before connecting to the product input or output terminals. A
protective ground connection by way of the grounding conductor in the mainframe power cord is essential for safe
operation.

7B87 Instruction
DANGER ARISING FROM LOSS OF GROUND
Upon loss of the protective-ground connection, all accessible conductive parts (including knobs and controls that may
appear to be insulating), can render an electric shock.
DO NOT OPERATE IN EXPLOSIVE ATMOSPHERES
To avoid explosion, do not operate this product in an atmosphere of explosive gases unless it has been specifically
certified for such operation.
DO NOT OPERATE PLUG-IN UNIT WITHOUT COVERS
To avoid personal injury, do not operate this product without covers or panels installed. Do not apply power to the plug-in
unit via a plug-in extender.
vi

7887 Instruction
SERVICING SAFETY SUMMARY
FOR QUALIFIED SERVICE PERSONNEL ONLY
Refer also to the preceding Operators Safety Summary
DO NOT SERVICE ALONE
Do not perform internal service or adjustment of this product unless another person capable of rendering first aid and
resuscitation is present.
USE CARE WHEN SERVICING WITH POWER ON
Dangerous voltages exist at several points in this product. To avoid personal injury, do not touch exposed connections
and components while power is on.
Disconnect power before removing protective panels, soldering, or replacing components.
POWER SOURCE
This product is intended to operate in a mainframe connected to a power source that will not apply more than 250 volts
rms between the supply conductors or between either supply conductor and ground. A protective ground connection by
way of the grounding conductor in the mainframe power cord is essential for safe operation,
vii

7B87 Instruction
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. TIME BASE =o
W/PRETRIGGER
ACQUIRE
CLOCK)
2788.1
7B87 FEATURES
The 7887 Time-Base unit Pretrigger Acquire Clock provides calibrated sweep rates from 5 seconds to 10 nanoseconds and triggering to 400
megahertz for 7000-Series Oscilloscopes. A X10 Magnifier increases each sweep rate by a factor of 10 and a VARIABLE TIME/DIV control
provides continuously-variable sweep rates between calibrated steps. Variable holdoff and alphanumeric readout are provided. Also, when
operating in the AUTO TRIGGERING MODE, a bright baseline trace is displayed in the absence of a trigger signal. The 7B87 can be operated
as an independent time base or as a delayed-sweep unit with a companion delaying time-base unit. Sweep mode is determined by the
companion delaying time base
The
7887 also features an internally-generated clock and an external clock input for sequential single sweep acquisition when operating ina
7000-series digitizing oscilloscope. The frequency range of the internally generated clock is 20.48 mHz (millihertz) to 20.48 MHz as
determined by the TIME/DIV, X10 MAG, and INT = 1000 switches. Also, an ACQUIRE-STOP DELAY function varies delay pickoff, and
therefore pretrigger time, in compatible digitizing plug-in oscilloscopes. The portion of the oscilloscope real-time display between the
triggering event and the end of delay time is intensified. The exact delay time is displayed on the crt readout