Tektronix 7B71 User manual

Tektronix, Inc.
P.O. Box 500
Beaverton, Oregon 97005
TEKTRONIX®
DELAYING
TIME BASE
SN B2050D0 AND UP
INSTRUCTION MANUAL
Serial Number 'JtXiiD ~~ ^
070-1580-00 373

WARRANTY
All TEKTRONIX instruments are warranted against
defective 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 repair 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 parte or
service. .j, ** || ''
'''-s.’
Specifications and price change privileges reserved.
Copyright ©1973 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 aregistered trademark of Tektronix, Inc.

7B71 (SN B205000and Up)
TABLE OF CONTENTS
Page
SECTION 1SPECIFICATIONS
Introduction 1-1
Electrical Characteristics 1-1
Sweep Rate 1-1
Sweep Accuracy 1-1
Sweep Length 1-1
Sweep Hold-Off Time 1-1
Variable Time Delay 1-1
Delay Time Range 1-1
Differential Delay Time Measurement Accuracy 1-1
Jitter 1-2
Trigger Sensitivity 1-2
Internal Trigger Jitter 1-2
External Trigger Input 1-2
Level Range 1-2
P-P Auto Sensitivity 1-2
Environmental Characteristics
Altitude 1-2
Physical Characteristics
Finish 1-2
Dimensions 1-2
Weight 1-2
SECTION 2OPERATING INSTRUCTIONS
General 2-1
Installation 2-1
Front Panel Controls 2-1
Test Setup Chart 2-4
General Operating Information 2-4
Sweep Calibration Check 2-4
Simplified Operating Instructions 2-6
Normal Sweep 2-6
Magnified Sweep 2-6
Delayed Sweep 2-6
Pushbutton Switch Logic 2-6
Triggered Light 2-7
Trigger Mode 2-7
Trigger Coupling 2-9
Trigger Source 2-10
Trigger Slope 2-10
Trigger Level 2-10
Horizontal Sweep Rate 2-12
Sweep Magnifier 2-12
Horizontal Position Control 2-13

7B71 (SN B205000and Up)
TABLE OF CONTENTS (cont)
Page
SECTION 2OPERATING INSTRUCTIONS (cont)
Applications 2-13
General 2-13
Measurement Techniques 2-13
Time Duration Measurements 2-14
Determining Frequency 2-15
Risetime Measurements 2-15
Delay Sweep Time Measurements 2-16
Delayed Sweep Magnification 2-17
Displaying Complex Signals Using Delayed Sweep 2-18
Pulse Jitter Measurements 2-18
SECTIONS CIRCUIT DESCRIPTION
Introduction 3-1
Block Diagram Description 3-1
Detailed Circuit Description 3-1
Trigger Input 3-1
Input Source 3-1
Trigger Amplifier 3-2
General 3-2
External Input Amplifier 3-2
Input Stage 3-2
Peak Detector 3-3
Slope Comparator 3-3
Output Stage 3-4
Trigger Generator 3-4
Trigger Pulse Generator 3-4
Sweep Gate Stage 3-4
Triggered Hold-Off Stage 3-4
Bright Line Auto 3-5
Time-Base Generator 3-5
General 3-5
Normal Trigger Mode Operation 3-5
Single Sweep Operation 3-8
Alternate Operation 3-8
Delayed Sweep Operation 3-8
Delay Pickoff 3-9
Horizontal Preamp 3-9
Readout Block 3-9
SECTION 4MAINTENANCE
Preventive Maintenance 4-1
General 4-1
Cleaning 4-1
Visual Inspection 4-1
Transistor and Integrated Circuit Checks 4-1
Recalibration 4-1

7B71 (SIM B205000 and Up)
TABLE OF CONTENTS (cont)
SECTION 4MAINTENANCE (cont) Page
Troubleshooting 4-2
Troubleshooting Aids 4-2
Troubleshooting Equipment 4-2
Troubleshooting Techniques 4-2
Corrective Maintenance 4-6
General 4-6
Obtaining Replacement Parts 4-6
Soldering Techniques 4-7
Component Replacement 4-7
Instrument Repackaging 4-10
SECTION 5PERFORMANCE CHECK/CALIBRATION
Introduction 5--|
Test Equipment Required 5-1
Short-Form Procedure and Index 5-2
Performance Check/Calibration Procedure 5-4
General 5-4
Preliminary Control Settings 5-5
Check/Adjust Steps (refer to Short-Form Procedure 5-5
for index to steps)
SECTION 6ELECTRICAL PARTS LIST
Abbreviations and Symbols
Parts Ordering Information
Index of Electrical Parts List
SECTION 7DIAGRAMS
SECTIONS MECHANICAL PARTS LIST
CHANGE INFORMATION
Abbreviations and symbols used in this manual are based on or
taken directly from IEEE Standard 260 "Standard Symbols for
Units", MIL STD-1 2B and other standards of the electronics
industry. Change information, if any, is located at the rear of this
manual.

TRiGGERING
WOOE COUPlfPiG SOURCE
P-PAOTO AC iNT
rmc'D I
LEVEl/SLOPE
SiNGlE
FINE
POSITION R^T MAGNIFIER
READY-
VARJABiE (CAL IN)
time/div ORDLYTIME
BDELAY MODE
(A INTER DURING 8}
II INDEPENDENT
BSTARTS
AFTER DELAY
8TRIGGERABLE
AFTER DELAY
DELAY TIME MULT
DELAYING TIME BASE
7B71
Fig. 1-1. 7B71 Delaying Time Base.
7B71 (SN B205000and Up)

7B71 (SN B205000and Up)
SECTION 1
7B71 SPECIFICATION
Change information,if any,affecting this section will be found at the rear of the manual.
Introduction
The 7B71 Time Base Unit is designed specifically for use
with Tektronix 7700-Series Oscilloscopes. However, it is
compatible with all 7000-Series Oscilloscopes. The 7B71
provides calibrated sweeps from 5seconds/division to 0.02
microseconds/division (2 nanoseconds/division with X10
MAGNIFIER). Sweep rates may be varied continuously
(uncalibrated) between calibrated steps. Sweep triggering is
to 200 megahertz or vertical amplifier bandwidth, which-
ever is less. The delaying sweep feature of the 7B71, in
delayed sweep operation, gives continuous sweep delay
from 0to 10 times the setting of the TIME/DIV OR DLY
TIME selector. The sweep free-runs providing abright base-
line in the absence of adequate triggering signal in P-P
AUTO and AUTO triggering modes.
The Performance Check procedure given in Section 5of
this manual provides aconvenient method of checking per-
formance of this instrument. The following electrical
characteristics apply at an ambient temperature of 0°C to
+50 C, unless otherwise noted. Warmup time for given
accuracy is 20 minutes.
TABLE 1-1
Electrical Characteristics
Characteristic Performance
Sweep Rate
Calibrated Range 5seconds/division to 0.02 micro-
seconds/division in a1-2-5 se-
quence. X10 magnifier extends
sweep rate to 2nanoseconds/
division.
VARIABLE Range
(uncalibrated)
Continuously variable between cali-
brated sweep rates. Extends uncali-
brated sweep rate to at least 12.5
seconds/division.
Sweep Accuracy Measured in 7000 series mainframe
Time Interval +15°Cto +35°C 0°C to +50°C
Over Center Unmag Mag Unmag Mag
8div
5s/div to 0.1
s/div and 0.2
ys/div to 0.02
ys/div
3% 3.5% 4% 5%
50 ms/div to
0.5 ys/div
2% 2.5% 3% 4%
Over any 2div
interval within
center 8div
5% 7%
a
Characteristic Performance
Excluded Divisions
of Magnified Sweep Start of Sweep; 12 ns in 7900
series, 20 ns in 7704A, and 50 ns in
other 7000 series mainframes.
End of Sweep; beyond the 90th
division
Sweep Length 10 divisions to 13 divisions.
Sweep Hold-Off Time
5s/div to
5ys/div
1.5 times the TIME/DIVISION set-
ting or less.
2ys/div to
0.02 ys/div
3.5 microseconds or less.
Variable Time Delay
Delay Time Range 0to 10 times DELAY TIME/DIV
setting from 5s/div to 1ys/div.
Differential Delay
Time Measurement
Accuracy
(+15°Cto +35° C)
5s/div to 1s/div
±(1.5% of measurement +0.3% of
full scale).
1-1

Specification-7871 (SN B205000 and Up)
TABLE 1-1 (cont)
Characteristic Performance
0.5 s/div to 1/Js/div ±(1 %of measurement +0.3% of full
scale). Full scale is 10 times the
DELAY TIME/DIV setting. Accu-
racy applies over the center 8major
DTM divisions.
Jitter 1part or less in 50,000 of 10 times
the TIME/DIV setting.
Trigger Sensitivity Triggering
Frequency
Range*
Minimum Trig-
gering Signal
Required
Coupling INT EXT
AC 30 Hz to
20 MHz 0.3 div 75 mV
20 MHz to
200 MHz 1.5 div 375 mV
AC LF REJ2 30 kHz to
20 MHz 0.3 div 75 mV
20 MHz to
200 MHz 1.5 div 375 mV
AC HF REJ 30 Hz to
50 kHz 0.3 div 75 mV
DC DC to
20 MHz 0.3 div 75 mV
i
20 MHz to
200 MHz 1.5 div 375 mV
Single Sweep Triggering requirements same as
normal sweep. When triggered,
sweep generator produces one
sweep only.
Internal Trigger Jitter 1nanosecond
hertz.
or less at 150 mega-
External Trigger Input
Maximum Input
Voltage
500 volts (DC +Peak AC). 500
volts (P-P AC) at 1kilohertz or less.
On Internal Triggering Only; the specified upper —3 dB frequency
of the Vertical System replaces upper limit frequencies in the
above table when the number in the table is greater than the —3 dB
frequency of the Vertical System.
2Will not trigger on sine waves of 3divisions or less internal or 1.5
volts external below 120 Hz.
TABLE 1-1 (cont)
Characteristic Performance
Input Rand C1megohm within 2%, 20 picofarads
within 2picofarads.
Level Range
(Excluding
P-P AUTO)
EXT
EXT+ 10
At least +1 .5 volts to —1 .5 volts.
At least +15 volts to —15 volts.
P-P AUTO operation
Sensitivity 0.5 div Internal, 125 millivolts
External 200 Hz to 20 MHz. Upper
frequency and amplitude limits
same as NORMAL Trigger Sensi-
tivity.
Low Frequency
Response
Must Trigger on 50 hertz, 2division
signal.
TABLE 1-2
Environmental Characteristics
This instrument will meet the electrical characteristics given
in Table T1 over the following environmental limits.
Characteristic Performance
Altitude
Non-operating To 50,000 feet and -55" C.
TABLE 1-3
Physical Characteristics
Finish Front panel is anodized aluminum.
Dimensions Fits single plug-in compartment of
7000-series oscilloscope.
Weight Approximately 2.88 pounds.
1-2

7B71 (SN B205000and Up)
SECTION 2
OPERATING INSTRUCTIONS
Change information, if any, affecting this section will be found at the rear of the manual.
General
The 7B71 delaying sweep plug-in unit operates with a
Tektronix 7000-series indicator oscilloscope and a7A-series
vertical plug-in unit to form acomplete oscilloscope
system. To use the 7B71 effectively, its operation and
capabilities should be known. This section describes the
operation of the front-panel controls, gives first-time and
general operating information and lists some basic applica-
tions for this instrument.
Installation
The 7B71 is designed to operate in the horizontal plug-in
compartments of Tektronix 7000-series oscilloscopes. The
7B71 can also be installed in avertical plug-in compartment
to provide asweep that runs vertically on the CRT. How-
ever, when used in this manner, there is no retrace blanking
or internal triggering provision and the unit may not meet
the specifications given in Section 1. The instructions in
this manual are written for use of the 7B71 in ahorizontal
plug-in compartment of the oscilloscope.
When the 7B71 is used with an oscilloscope which has
two horizontal plug-in compartments, install this unit in the
A(DELAYING TIME BASE) compartment. Then, if a
delayed-sweep unit is installed in the B(right) compart-
ment, delayed-sweep operation is available. The 7B71 will
operate properly in the Bcompartment for all horizontal
modes of operation except delaying sweep.
To install the 7B71 into aplug-in compartment, push it
in until it fits firmly into the indicator plug-in compart-
ment. To remove, pull the release latch (see Fig. 2-1) to
disengage the unit from the indicator and pull it out of the
plug-in compartment. Even though the horizontal gain of
the indicator oscilloscope is standardized to minimize
adjustment when inserting plug-in units, the sweep calibra-
tion of the 7B71 should be checked when it is inserted into
the indicator to verify measurement accuracy. The pro-
cedure for checking the unit is given under Sweep Calibra-
tion Check in this section.
FRONT-PANEL CONTROLS
General
All controls required for the operation of the 7B71 are
located on the front panel of the unit (see Fig. 2-2). To
Release
Latch
Fig. 2-1. Location of release latch.
make full use of the capabilities of this instrument, the
operator should be familiar with the function and use of
each of these controls. Abrief description of the front-
panel controls and connector is given here. More detailed
information is given under General Operating Information.
Triggering Controls
LEVEL/SLOPE Selects the amplitude point and
slope of trigger signal on which the
sweep is triggered. When the indica-
tor line on the outer ring is to the
left of center, the sweep is triggered
on the positive-going slope of the
trigger signal, as shown by the
positive-going waveform. To the
right of center, the sweep is trig-
gered on the negative-going slope of
the trigger signal as shown by the
negative-going waveform.
TRIC'D Light indicates that the sweep is
triggered and will produce adisplay
with correct setting of the POSI-
TION control and the controls on
the associated vertical unit and indi-
cator oscilloscope.
[A] 2-1

MODE COUPUNG SOURCE
PPAUTO AC INT
LEVEL/SLOPE
INOEPENDEN1
Operating lnstructions-7B71 (SN B205000 and Up)
TRIC'D 0TRIGGERING
TRIGGER
CONTROLS
AUTO ACIFREJ tIN£
NORM ACHFREJ EXT
SINGLE
SWP -I DC EXT ^10
FINE
POSITION
.ARIAIU fCAL IN
ime/divor dly time
BDELAY MODE
lA INTER DURING I-
SWEEP
CONTROLS
BSTARTS 1,.
AFTER DEUY /50
BTRIGGERABLE
AFTER DEUY
DELAY
CONTROLS DEUY TME MULT
TRIGGER
CONTROL
Fig. 2-2. Front-Panel controls and connectors.
MODE Series of push-button switches to
select the trigger mode. Selected
mode is indicated by lighted
button.
P-P AUTO: Sweep automatically
triggered at point selected by the
LEVEL/SLOPE control when
the trigger signal repetition rate
is above about 200 hertz and
within the frequency range
selected by the COUPLING
switch. Triggered sweep can be
obtained throughout the range
of the LEVEL/SLOPE control.
When the trigger repetition rate
is below the lower frequency
limit (or above upper limit for
AC HF REJ) or when the trigger
signal is inadequate, the sweep
free runs at the sweep rate
selected by the TIME/DIV
switch to produce areference
trace.
2-2 lA]