Tektronix 7B50A User manual

7B5DA
TIME BASE
WITH O PTIONS

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WARRANTY
All TEKTRONIX instruments are warranted against
defective materials
and workmanship for one year.
Any questions with respect to the warranty should
betaken
up with yourTEKTRONIX FieldEngineer or
representative~
All requests for repairs and replacement parts
should be directed to ;'1\e 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.
Specificationsand pricechangeprivilegesreserved.
Copyright (C) 1975 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.andforeign patents and/or patentspending.
TEKTRONIX is a registered trademark of Tektronix,
Inc.

7B50A Instruction
TABLE OF CONTENTS
PAGE PAGE
LIST OF
ILLUSTRATIONS ................... iii
Trigger Slope .................... 1-7
LIST OF TABLES .......................... iv Trigger Level . . . . . . . . . . . . . . . . . .
.. 1-7
SAFETY SUMMARY ......................... v Horizontal
Sweep Rates ............. 1-7
SECTION 1 OPERATING INSTRUCTIONS Time Measurement
................ 1-7
@
INSTALLATION ................... 1·1
CONTROLS, CONNECTORS,
AND INDICATORS .................. 1-1
FUNCTIONAL CHECK ............... 1-1
Setup Procedure. . . . . . . . . . . . . . . . . . 1-1
Sweep Functions. . . . . . . . . . . . . . . . . . 1-4
Triggering Functions . . . . . . . . . . . . . . . 1-4
GENERAL OPERATING INFORMATION .. 1-5
Triggering Switch Logic
............. 1-5
Triggering Modes .................. 1-5
Sweep Magnification
............... 1-7
Variable Hold Off ................. 1-7
Mainframe Operating Modes . . . . . . . . . . 1-9
APPLICATIONS ........................ 1-10
TIME-INTERVAL MEASUREMENTS ..... 1-10
Period
and Frequency Measurements ..... 1-10
Rise-Time and Fall-Time Measurements ... 1-11
Pulse Width Measurements ........... 1-12
DELAYED-SWEEP MEASUREMENTS ..... 1-12
X-Y PHASE MEASUREMENTS .......... 1-12
Trigger Coupling
.................. 1-6 SECTION 2 SPECIFICATION
Trigger Source . . . . . . . . . . . . . . . . . . . 1-6
STANDARD ACCESSORIES ........... 2-3
WARNING
THE REMAINING SECTIONS OF THIS MANUAL CONTAIN SER-
VICING 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 IN-
STRUCTIONS UNLESS
QUALIFIED TO DO SO.
----------------------------------~~----- ----~-

7B50A Instruction
TABLE OF CONTENTS (CONT.)
PAGE
SECTION 3 THEORY OF OPERATION
BLOCK DIAGRAM DESCRIPTION ........... 3-1
DETAILED CIRCUIT DESCRIPTION ......... 3-1
LOGIC FUNDAMENTALS ............. 3-1
NON-DIGITAL DEVICES .............. 3-2
FRONT-PANEL DISTRIBUTION ~> .... 3-7
TRIGGER GENERATOR 0 .......... 3-7
LOGIC 0 ...................... 3-9
SWEEP
GENERATOR 0 ............3-11
TIME/DIVISION READOUT ~ ........ 3-14
INTERFACE CONNECTORS AND
POWER SUPPLY <§> ...............3-14
SECTION 4 MAINTENANCE
PREVENTIVE MAINTENANCE ............. 4-1
CLEANING ....................... 4-1
VISUAL INSPECTION ................ 4-1
LUBRICATION .................... 4-1
SEMICONDUCTOR CHECKS ........... 4-2
ADJUSTMENT AFTER REPAIR ..•...... 4-2
TROUBLESHOOTING .................... 4-3
TROUBLESHOOTING AIDS ........... 4-3
TROUBLESHOOTING EQUIPMENT ...... 4-5
TROUBLESHOOTING TECHNIQUES ..... 4-6
CORRECTIVE MAINTENANCE ............. 4-9
OBTAINING REPLACEMENT PARTS ..... 4-9
ii
PAGE
SOLDERING TECHNIQUES ............ 4-9
COMPONENT REMOVAL AND
REPLACEMENT ................... .4-10
Circuit Boards ................... .4-10
Switches ...................... .4-12
Semiconductors ................. .4-12
Interconnecting Pins .............. .4-13
Front-Panel Lights ................ .4-16
ADJUSTMENT AFTER REPAIR .. , ..... .4-16
INSTRUMENT REPACKAGING ........ .4-16
SECTION 5 PERFORMANCE CHECK AND
ADJUSTMENT
PRELIMINARY INFORMATION ........ 5-1
TEST EQUIPMENT REQUIRED ......... 5-1
INDEX TO PERFORMANCE CHECK
AND ADJUSTMENT PROCEDURE ....... 5-3
PRELIMINARY PROCEDURE .......... 5-3
SECTION 6 REPLACEABLE ELECTRICAL PARTS
SECTION 7
INSTRUMENT OPTIONS
SECTION 8
DIAGRAMS AND CIRCUIT BOARD
ILLUSTRATIONS
SECTION 9 REPLACEABLE MECHANICAL PARTS
CHANGE INFORMATION
@
--~---

FIGURE
NO.
@
1-1
1-2
1-3
1-4
1-5
1-6
1-7
1-8
2·1
3-1
3-2
3-3
3-4
3-5
3-6
4-1
4-2
4-3
4-4
7B50A Instruction
LIST OF ILLUSTRATIONS
PAGE
Frontispiece ...................... vi
Location of release latch. . . . . . . . 1-1
Front-panel controls, connectors,
and
indicators. . . . . . . . . . . . . . . 1-2
Effect of LEVEL control and SLOPE
switch on crt display . . . . . . . . . . . 1-8
Area
of graticule used for most accurate
time measurements . . . . . . . . . . . . . . . . 1-9
Operation
of sweep magnifier . . . . . . 1-9
Measuring the period and
determining
the frequency of a displayed waveform ... 1-10
Measuring the rise time and fall time of
a displayed waveform ............... 1-11
Measuring the pulse
width of a displayed
waveform ....................... 1-12
7B50A dimensional drawing. . . . . . 2-3
Basic block diagram of the 7B50A
Time-Base Unit. . . . . . . . . . . . . . . 3-2
Detailed
block diagram of Trigger
Generator . . . . . . . . . . . . . . . . . . . 3-6
Functional diagram of Trigger Source
Selector. . . . . . . . . . . . . . . . . . . . . 3-8
Timing diagram for Gate Generator
(092, 096, 098). . . . . . . . . . . . . . . 3-9
Detailed
block diagram of Logic circuit ... 3-10
Detailed
block diagram of Sweep
Generator . . . . . . . . . . . . . . . . . .3-12
Lubrication procedure for a typical
cam switch. . . . . . . . . . . . . . . . 4-2
Semiconductor lead configuration ..... . 4-4
Inter-board multi-pin connector
assembly .............. . 4-5
End-lead
multi-pin connector
assembly ...................... . 4-5
FIGURE
NO.
4-5 Location of pin numbers on Interface
PAGE
connector . . . . . . . . . . . . . . . . . . . . . . 4-5
4-6
7B50A troubleshooting chart. . . . . . . 4-8
4-7 Readout board removal procedure
..... .4-11
4-8 Coaxial end-lead connector assembly .... .4-12
4-9 Cam switch removal procedure
........ .4-14
4-10
4-11
4-12
Removal procedure
for typical
push-button switch ........... .
Exploded view
of circuit-board pin
and ferrule ................ .
Front-panel
light socket assembly ..
.4-15
.4-16
.4-16
The
illustrations in Section 8 are located near their associat-
ed Diagrams on the foldout pages.
8-1 Semiconductor lead configurations.
8-2
Location of circuit boards in the 7B50A.
8-3 A 1-lnterface circuit board assembly.
8-4 A2- Trigger circuit board assembly.
8-5
A3-Readout circuit board assembly.
8-6 A
1-lnterface circuit board assembly.
8-7
A2- Trigger circuit board assembly.
8-8 A
1-1 nterface circuit board assembly.
8-9 A
1-1 nterface circuit board assembly.
8-10
A3--Readout circuit board assembly.
8-11
A1-lnterface circuit board assembly.
8-12
A3-Readout circuit board assembly.
8-13 A
1-1 nterface circuit board assembly.
8-14
A5-X-Y Switch circuit board assembly.
8-15
Location of Sweep Timing adjustments.
8-16
Location of Triggering adjustments.
iii

7B50A Instruction
LIST OF TABLES
TABLE
NO.
2-1
2-2
2-3
3-1
iv
PAGE
Electrical Characteristics ............. 2-1
Environmental Characteristics ......... 2-3
Physical Characteristics
.............. 2-3
Basic Logic Reference
.............. 3-3
TABLE
NO.
3-2
5-1
5-2
5-3
PAGE
Readout Character Selection .......... 3-15
Test Equipment .................. 5-2
Sweep Timing .................... 5-10
Magnified Sweep Timing ............. 5-10
@

r----
7B50A Instruction
SAFETY SUMMARY
This manual contains safety information which the user must follow to ensure safe operation of this instrument. WARN ING
information is intended to protect the operator; CAUTION information is intended to protect the instrument. The following
are general safety precautions that must be observed during all phases of operation and maintenance.
[WARNIN<!:I
Ground the Instrument
To reduce electrical-shock hazard, the mainframe (oscilloscope) chassis must be properly grounded. Refer to the mainframe
manual for grounding information.
Do Not Operate in Explosive Atmosphere
Do not operate this instrument in an area where flammable gases or fumes are present. Such operation could cause an
explosion.
Avoid Live Circuits
Electrical-shock hazards are present in this instrument. The protective instrument covers must not be removed by operating
personnel.
Component replacement and internal adjustments must be referred to qualified service personnel.
Do Not Service or Adjust Alone
Do not service or make internal adjustments to this instrument unless anotherperson, capable of giving first aid and resusci-
tation,
is present.
Warning Statements
Warning statements accompany potentially dangerous procedures in this manual. The following warnings appear in this
manual and are listed here for additional emphasis.
To avoid electrical shock, disconnect the instrument from the power source before soldering.
To avoid electrical shock, disconnect the instrument from the power source before replacing components.
Handle silicone grease with
care. A void getting silicone grease in eyes. Wash hands thoroughly after use.
@ v

7850A Instruction
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TIME BASE
7B50A __ ~..:...;,...;.._~
7B50A FEATURES
The 7B50A Time-Base
unit provides calibrated sweep rates from 5 seconds to 50 nanoseconds and triggering to 150 mega-
hertz for 700Q-series oscilloscopes. A
Xl0 Magnifier increases each sweep rate by a factor of 10 and a VAR IABLE TIME/ DIV
control provides continuously variable sweep rates between calibrated steps. Variable hold off and alphanumeric readout are
provided. Also. when operating
in the AUTO TA IGGER ING MODE, a bright baseline trace is displayed in the absence of a
trigger signal. The
7850A can' be operated as an independent time base or as a delayed-sweep unit with a companion delay-
ing time-base unit, Sweep mode is determined by the companion delaying time base.
1985-2
,;
"
--., -

Section 1-7B50A
OPERATING INSTRUCTIONS
The lB50A Time-Base unit operates with a Tektronix lOOO-series oscilloscope mainframe and a lA-series amplifier unit to
form a complete oscilloscope system. This section describes the operation of the front-panel controls and connectors, pro-
vides general operating information, a functional check procedure, and basic applications for this instrument.
INSTALLATION
The time-base unit is designed to operate in the horizontal
plug-in compartment of the mainframe. This instrument
can also be installed in a vertical plug-in compartment to
provide a vertical sweep on the crt. However, when used in
this manner, there are no internal triggering or retrace
blanking provisions, and the unit may not meet the specifi-
cations given in Section 2.
2. Install
an amplifier plug-in unit in a vertical compart-
ment.
3. Set the time-base unit controls as follows:
(+)
Pop AUTO
AC
INT
Midrange
1 ms
To install the unit in a plug-in compartment, push it in until
it fits firmly into the compartment. The front panel of the
unit should be flush with the front panel of the mainframe.
Even though the gain of the mainframe is standardized, the
sweep calibration of the unit should be checked when in-
stalled. The procedure for checking the unit is given under
Sweep Functions in the Functional Check procedure in this
section.
SLOPE
MODE
COUPLING
SOURCE
POSITION
TIME/DIV
VARIABLE Calibrated (Pushed in)
To remove the unit, pull the release latch (see Figure 1-1)
to disengage the unit from the mainframe, and pull it out of
the plug-in compartment.
CONTROLS, CONNECTORS, AND INDICATORS
All controls, connectors, and indicators required for the
operation of the time-base unit are located on the front
panel. Figure 1-2 shows and provides a brief description of
all front-panel controls, connectors, and indicators. More
detailed information is given in the General Operating
Instructions.
FUNCTIONAL CHECK
The following procedures are provided for checking basic
instrument functions. Refer to the description of the con-
trols, connectors, and indicators while performing this pro-
cedure. If performing the functional check procedure
reveals a malfunction or possible improper adjustment, first
check the operation of the associated plug-in units, then re-
fer to the instruction manual for maintenance and adjust-
ment procedures.
Setup Procedure
1. Install the time-base unit being checked in the A hori-
zontal compartment of the mainframe.
@
(CAL IN)
HOLD OFF
MAG
MIN (fully counter-
clockwise)
X1 (pushed in)
4. Turn on the mainframe and allow at least 20 minutes
warmup.
EXT TRIG IN
IMn
. 17Br I~___ TIMEB~E
RELEASE
LATCH
1985-3
Fig. 1-1. Location of release latch.
1-1