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7B80 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
Time Measurement . . . . . . . . . . . . . . . . 1-7
SECTION 1 OPERATING INSTRUCTIONS
Sweep Magnification . . . . . . . . . . . . . . . 1-7
INSTALLATION . . . . . . . . . . . . . . . . . . . 1-1
Variable Hold Off . . . . . . . . . . . . . . . . . 1-7
CONTROLS, CONNECTORS,
AND INDICATORS . . . . . . . . . . . . . . . . . . 1-1 Mainframe Operating Modes . . . . . . . . . . 1-9
FUNCTIONAL CHECK . . . . . . . . . . . . . . . 1-1 APPLICATIONS . . . . . . . . . . . . . . . . . . . . . . . .1-10
Setup Procedure . . . . . . . . . . . . . . . . . . 1-1 TIME-INTERVAL MEASUREMENTS . . . . .1-10
Sweep Functions . . . . . . . . . . . . . . . . . . 1-4 Period and Frequency Measurements . . . . .1-10
Triggering Functions . . . . . . . . . . . . . . . 1-4 Rise-Time and Fall-Time Measurements . . .1-11
GENERAL OPERATING INFORMATION . . 1-5 Pulse Width Measurements . . . . . . . . . . . 1-12
Triggering Switch Logic . . . . . . . . . . . . . 1-5 DELAYED-SWEEP MEASUREMENTS . . . . .1-12
Triggering Modes . . . . . . . . . . . . . . . . . . 1-5 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 . T O AVOID
ELECTRICAL SHOCK, DO NOT PERFORM ANY SERVICING
OTHER THAN THAT CALLED OUT IN THE OPERATING IN-
STRUCTIONS UNLESS QUALIFIED TO DO SO.
71380 Instruction
TABLE OF CONTENTS (CONT.)
PAGE PAGE
SECTION 3 THEORY OF OPERATION SOLDERING TECHNIQUES . . . . . . . . . . . . 4-9
BLOCK DIAGRAM DESCRIPTION . . . . . . . . . . . 3-1 COMPONENT REMOVAL AND . . . . . . . .
REPLACEMENT. . . . . . . . . . . . 4-10
DETAILED CIRCUIT DESCRIPTION . . . . . . . . . 3-1
Circuit Boards . . . . . . . . . . . . . . . . . . . .4-10
LOGIC FUNDAMENTALS . . . . . . . . . . . . . 3-1
Switches . . . . . . . . . . . . . . . . . . . . . . .4-12
NON-DIGITAL DEVICES. . . . . . . . . . . . . . 3-2
Semiconductors . . . . . . . . . . . . . . . . . .4-12
FRONT-PANEL DISTRIBUTION O1 . . . . . 3-7
TRIGGER GENERATOR
O. . . . . . . . . .
LOGIC 03 . . . . . . . . . . . . . . . . . . . . . . . 3-9
3-7
Interconnecting Pins . . . . . . . . . . . . . . .4-13
Front-Panel Lights . . . . . . . . . . . . . . . . .4-16
ADJUSTMENT AFTER REPAIR . . . . . . . . .4-16
SWEEP GENERATOR 4O . . . . . . . . . . . .3-11
INSTRUMENT REPACKAGING . . . . . . . . .4-16
TIME/DIVISION READOUT O5 . 3-14
. . . . . . .
INTERFACE CONNECTORS AND SECTION 5 PERFORMANCE CHECK AND
POWER SUPPLY <~> . . . . . . . . . . . . . . .3-14 ADJUSTMENT
PRELIMINARY INFORMATION . . . . . . . . 5-1
SECTION 4 MAINTENANCE
TEST EQUIPMENT REQUIRED . . . . . . . . . 5-1
PREVENTIVE MAINTENANCE . . . . . . . . . . . . . 4-1
INDEX TO PERFORMANCE CHECK
CLEANING . . . . . . . . . . . . . . . . . . . . . . . 4-1 AND ADJUSTMENT PROCEDURE . . . . . . . 5-3
VISUAL INSPECTION . . . . . . . . . . . . . . . . 4-1 PRELIMINARY PROCEDURE . . . . . . . . . . 5-3
LUBRICATION . . . . . . . . . . . . . . . . . . . . 4-1
SECTION 6 REPLACEABLE ELECTRICAL PARTS
SEMICONDUCTOR CHECKS . . . . . . . . . . . 4-2
ADJUSTMENT AFTER REPAIR . . . . . . . . . 4-2 SECTION 7 INSTRUMENT OPTIONS
TROUBLESHOOTING. . . . . . . . . . . . . . . . . . . . 4-3 SECTION 8 DIAGRAMS AND CIRCUIT BOARD
ILLUSTRATIONS
TROUBLESHOOTING AIDS . . . . . . . . . . . 4-3
TROUBLESHOOTING EQUIPMENT . . . . . . 4-5 SECTION 9 REPLACEABLE MECHANICAL PARTS
TROUBLESHOOTING TECHNIQUES . . . . . 4-6
CORRECTIVE MAINTENANCE . . . . . . . . . . . . . 4-9 CHANGE INFORMATION
OBTAINING REPLACEMENT PARTS . . . . . 4-9
71380 Instruction
LIST OF ILLUSTRATIONS
FIGURE FIGURE
NO . PAGE NO . PAGE
Frontispiece . . . . . . . . . . . . . . . . . . . . . . vi 4-5 Location of pin numbers on Interface
1-1 Location of release latch . . . . . . . . . . . . . 1-1 connector . . . . . . . . . . . . . . . . . . . . . . 4-5
1-2 Front-panel controls, connectors, 4-6 71380 troubleshooting chart . . . . . . . . . . . 4-8
and indicators . . . . . . . . . . . . . . . . . . . . 1-2 4-7 Readout board removal procedure . . . . . .4-11
1-3 Effect of LEVEL control and SLOPE 4-8 Coaxial end-lead connector assembly . . . . .4-12
switch on crt display . . . . . . . . . . . . . . . 1-8 4-9 Cam switch removal procedure. . . . . . . . .4-14
1-4 Area of graticule used for most accurate 4-10 Removal procedure for typical
time measurements . . . . . . . . . . . . . . . . 1-9 push-button switch . . . . . . . . . . . . . . . .4-15
1-5 - Operation of sweep magnifier . . . . . . . . . 1-9 4-11 Exploded view of circuit-board pin
1-6 Measuring the period and determining and ferrule . . . . . . . . . . . . . . . . . . . . . .4-16
the frequency of a displayed waveform . . .1-10 4-12 Front-panel light socket assembly . . . . . . .4-16
1-7 Measuring the rise time and fall time of
a displayed waveform . . . . . . . . . . . . . . .1-11
1-8 Measuring the pulse width of a displayed The illustrations in Section 8 are located near their associat-
waveform . . . . . . . . . . . . . . . . . . . . . . .1-12 ed Diagrams on the foldout pages .
2-1 71380 dimensional drawing . . . . . . . . . . . 2-3
3-1 Basic block diagram of the 71380
8-1 Semiconductor lead configurations .
Time-Base Unit . . . . . . . . . . . . . . . . . . . 3-2
8-2 Location of circuit boards in the 7880 .
3-2 Detailed block diagram of Trigger
8-3 A1-Interface circuit board assembly .
Generator . . . . . . . . . . . . . . . . . . . . . . 3-6
8-4 A2-Trigger circuit board assembly .
3-3 Functional diagram of Trigger Source
8-5 A3-Readout circuit board assembly .
Selector . . . . . . . . . . . . . . . . . . . . . . . . 3-8
8-6 A1-Interface circuit board assembly .
3-4 Timing diagram for Gate Generator
8-7 A2-Trigger circuit board assembly .
(Q92, Q96, Q98) . . . . . . . . . . . . . . . . . . 3-9
8-8 A1-Interface circuit board assembly .
3-5 Detailed block diagram of Logic circuit . . . 3-10
8-9 A1-Interface circuit board assembly .
3-6 Detailed block diagram of Sweep
8-10 A3-Readout circuit board assembly .
Generator . . . . . . . . . . . . . . . . . . . . . .3-12
8-11 A1-Interface circuit board assembly .
4-1 Lubrication procedure for a typical
8-12 A3-Readout circuit board assembly .
cam switch . . . . . . . . . . . . . . . . . . . . . . 4-2
8-13 A1-Interface circuit board assembly .
4-2 Semiconductor lead configuration . . . . . . 4-4
8-14 A5-X-Y Switch circuit board assembly .
4-3 Inter-board multi-pin connector
8-15 Location of Sweep Timing adjustments .
assembly . . . . . . . . . . . . . . . . . . . . . . . 4-5
8-16 Location of Triggering adjustments .
4-4 End-lead multi-pin connector
assembly . . . . . . . . . . . . . . . . . . . . . . . 4-5
71380 Instruction
LIST OF TABLES
TABLE TABLE
PAGE NO . PAGE
NO .
2-1 Electrical Characteristics . . . . . . . . . . . . . 2-1 3-2 Readout Character Selection . . . . . . . . . .3.15
2-2 Environmental Characteristics . . . . . . . . . 2-3 5-1 Test Equipment . . . . . . . . . . . . . . . . . . 5-2
2-3 Physical Characteristics . . . . . . . . . . . . . . 2-3 5-2 Sweep Timing . . . . . . . . . . . . . . . . . . . . 5-10
3-1 Basic Logic Reference . . . . . . . . . . . . . . 3-3 5-3 Magnified Sweep Timing . . . . . . . . . . . . . 5-11
71380 Instruction
SAFETY SUMMARY
This manual contains safety information which the user must follow to ensure safe operation of this instrument . WARNING
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 .
WARNING
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 another person, capable of giving first aid and resusci-
tation, is present.
WARNING
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 . Avoid getting silicone grease in eyes. Wash hands thoroughly after use.
71380 Features
The 7880 Time-Base unit provides calibrated sweep rates from 5 seconds to 10 nanoseconds and triggering to 400 megahertz
for 7700-, 7800-, and 7900-series oscilloscopes . A X10 Magnifier increases each sweep rate by a factor of 10 and a VARI-
ABLE TIME/DIV control provides continuously variable sweep rates between calibrated steps . Variable hold off and alpha-
numeric 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 71380 can be operated as an independent time base or as a delayed-sweep unit with a com-
panion delaying time-base unit .
1958-1
Section 1-71380
OPERATING INSTRUCTIONS
The 71380 Time-Base unit operates with a Tektronix 7700-, 7800-, and 7900-series oscilloscope mainframes and a 7A-series
amplifier unit to form a complete oscilloscope system . This section describes the operation of the front-panel controls and
connectors, provides general operating information, a functional check procedure, and basic applications for this instrument .
INSTALLATION 2. Install an amplifier plug-in unit in a vertical compart-
ment .
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 3. Set the time-base unit controls as follows :
provide a vertical sweep on the crt. However, when used in
this manner, there are no internal triggering or retrace SLOPE (+)
blanking provisions, and the unit may not meet the specifi- MODE P-P AUTO
cations given in Section 2. COUPLING AC
SOURCE INT
POSITION Midrange
To install the unit in a plug-in compartment, push it in until TIME/DIV 1 ms
it fits firmly into the compartment. The front panel of the VARIABLE Calibrated (Pushed in)
unit should be flush with the front panel of the mainframe . (CAL IN)
Even though the gain of the mainframe is standardized, the HOLD OFF MIN (fully counter-
sweep calibration of the unit should be checked when in- clockwise)
stalled . The procedure for checking the unit is given under MAG X1 (pushed in)
Sweep Functions in the Functional Check procedure in this
section .
4. Turn on the mainframe and allow at least 20 minutes
warmup .
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
I nstructions .
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 .
RELEASE
LATCH 1958-3
Setup Procedure
1 . Install the time-base unit being checked in the A hori-
zontal compartment of the mainframe. Fig. 1-1 . Location of release latch .
Fig. 1-2. Front-panel controls, connectors, and indicators.
Operating Instructions-7B80
TRIGGERING
LEVEL Control-Selects a point on the trigger signal where triggering occurs .
SLOPE Switch-Permits sweep to be triggered on negative or positive-going portions of the trigger signal .
READY Indicator-Illuminates when sweep circuit is armed (SINGLE SWEEP Mode) .
TRIG'D Indicator-Illuminates when the display is triggered .
MODE Pushbuttons-Selects the operating mode of the triggering circuit .
COUPLING Pushbuttons-Selects the method of coupling the trigger signal to triggering circuit.
SOURCE Pushbuttons-Selects source of the trigger signal .
SWEEP
POSITION Control-Provides horizontal positioning.
FINE Control-Provides precise horizontal positioning.
MAG Pushbutton-Selects magnified X10 or unmagnified sweep.
HOLD OFF Control-Permits hold off period to be varied to improve trigger stability on repetitive complex waveforms.
TIME/DIV Selector-Selects the sweep rate of the sweep generator.
VARIABLE Control and CAL Switch-Selects calibrated or uncalibrated sweep rates. Uncalibrated sweep rates can
be continuously reduced to at least the sweep rate of the next slower position .
SWP CAL Adjustment-Compensates for basic timing changes due to the differences in sensitivity of mainframes
EXTERNAL TRIGGER INPUT
EXT TRIG ATTENUATOR-Selects attenuation factor for external trigger signals .
EXT TRIG IN Connector-Connector (BNC type) provides input for external trigger signals.
1958-4
Fig. 1-2. Front-panel controls, connectors, and indicators (coat.) .
Operating Instructions-71380
5. Set the mainframe vertical and horizontal modes to dis- 2. Press to release the MAG button (X10). Note that the
play the plug-in units used and adjust the intensity and unmagnified display within the center division of the grati-
focus for a well-defined display . See the oscilloscope main- cule is magnified to about 10 divisions.
frame and amplifier unit instruction manuals for detailed
operating instructions .
3. Press the MAG button (X1) .
Sweep Functions
Triggering Functions
NORMAL SWEEP. Perform the following procedure to ob-
tain a normal sweep and to demonstrate the function of the Perform the following procedure to obtain a triggered
related controls : sweep and to demonstrate the functions of the related
controls :
1 . Perform the preceding Setup Procedure.
1 . Obtain a display as described in the preceding Normal
Sweep procedure.
2. Connect a 0.4-volt, 1-kilohertz signal from the main-
frame calibrator to the amplifier unit input.
2. Press the AUTO MODE button and turn the LEVEL
control fully counterclockwise to obtain a free-running
3. Set the amplifier unit deflection factor for 4 divisions of sweep.
display.
3. Slowly turn the HOLD OFF control clockwise and note
4. Adjust the LEVEL control for a stable display . that a stable display can be obtained at several positions of
the HOLD OFF control. Return the HOLD OFF control to
the fully counterclockwise (MIN) position .
5 . Turn the POSITION control and note that the trace
moves horizontally .
NOTE
The HOLD OFF control varies the sweep hold-off
6. Turn the FINE control and note that the display can be time which effectively changes the repetition-rate
precisely positioned horizontally . of the horizontal sweep signal. However, its pri-
mary function is to obtain a stable display of
complex waveforms which are otherwise difficult
7. Check the display for one complete cycle per division . If to trigger.
necessary, adjust the front-panel SWP CAL screwdriver ad-
justment for one complete cycle per division over the
center 8 graticule divisions. Be sure that the timing of the 4. Press the AC, AC HF REJ, and DC COUPLING buttons
mainframe calibrator signal is accurate to within 0.25% for both the + and - positions of the SLOPE switch and
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