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                                    7B80 Features

The 7B80 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
VARIABLE 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 TRIGGERING MODE, a bright baseline trace is
displayed in the absence of a trigger signal. The 7B80 can
be operated as an independent time base or as a
delayed-sweep unit with a companion delaying time-base unit.

LIST OF ILLUSTRATIONS...................iii

LIST OF TABLES..........................iv

SAFETY SUMMARY.........................v

SECTION 1 OPERATING INSTRUCTIONS

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

Trigger Coupling..................1-6

Trigger Source...................1-6
PAGE

Trigger Slope....................1-7

Trigger Level....................1-7

Horizontal Sweep Rates.............1-7

Time Measurement................1-7

Sweep Magnification...............1-7

Variable Hold Off.................1-7

Mainframe Operating Modes..........1-9

APPLICATIONS........................1-10

TIME-INTERVAL MEASUREMENTS.....MO

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

SECTION 2 SPECIFICATION

STANDARD ACCESSORIES...........2-3
WARNING

THE REMAINING SECTIONS OF THIS MANUAL CONTAIN 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...........3-1

DETAILED CIRCUIT DESCRIPTION.........3-1

LOGIC FUNDAMENTALS.............3-1

NON-DIGITAL DEVICES..............3-2

FRONT-PANEL DISTRIBUTION <^.____3-7

TRIGGER GENERATOR ..........3-7

LOGIC ......................3-9

SWEEP GENERATOR «> ,........

TIME/DIVISION READOUT <5>.......3-14

INTERFACE CONNECTORS AND

POWER SUPPLY <6>...............3,4

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
PAGE
SOLDERING TECHNIQUES........... 4-9
COMPONENT REMOVAL AND REPLACEMENT....................4
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