Tektronix 7B92A User manual

°
Tektronix, Inc .
P.O
. Box 500
Beaverton, Oregon

97077
COMMITl"ED TO
EXCELLENCE
RLSASS
~HE K
F'4R HANGS
IN~~R ATION
AT THE
REAR ~~'
THIS MANUAL
.
I N

TF~ U ~T I Q
N

M

loJ,~ L
Serial Number __ ._
070-1751-02

First Printing
JUN 1978
Product
Group 42

Revised
JUN 1987

LIST
OF ILLUSTRATIONS
............  ,.. 

iii
SAFETY
SUMMARY . . . ..................................
.

v
Page
SECTION
1

OPERATING
INSTRUCTIONS
INTRODUCTION
..........................
...... . .
. . . . . . 1-1
INSTALLATION ........................ .
. ...... .... .... 1-1
FRONT-PANEL
CONTROLS,
CONNECTORS, AND
INDICATORS .....

1-2
Main Triggering Controls ......................,.....,,, ,

1-2
Sweep Controls . . . . ..............................,,,. ,

1-4
Delayed Triggering Controls
..........................,, 1-5
Front-Panel I nputs

..........................,,.,,,,,, , ,

1-5
FUNCTIONAL CHECK .............................,.. . . . .

1-5
Setup Procedure ......................... ....  ,
1-6
Sweep Functions .........................     ,

1-6
Triggering
Functions ...................... ...... ... .., ,

1-7
GENERAL OPERATING
INFORMATION .......... . . . ... . . ... . .

1-8
Main Triggering .........................
... . . . . ..... . .

1-8
Main Trigger Modes ..................... . . . . . ...... ,,.,

1-8
Main Trigger Coupling ..............,... . . .   ,.,.  ,

1-9
Main Trigger
Source

................... ... .  , ... 

1-10
Input
Impedance ...................... ... .... .... .  . ,

1-10
Trigger Slope

.......................
... ....... . . .....

1-10
Trigger Level .......................
... ...... .... .....

1-10
Selecting Sweep Rates ................ . . ............,,,.

1-12
TimeMeasurement

.................. . .  .,.  ... 

1-12
Display Modes

.................
. . . . ..................

1-12
Delay
Time Multiplier ......... . . . ... ........,. 

1-13
Delayed Sweep Triggering

. .... ..... . . ...........,,,,,.,,

1-13
SECTION 2

SPECIFICATION ........ ... ...........,..  , .  . 

2-1
WARNING
THE FOLLOWING SERVICING INSTRUCTIONS
AREFOR USE BY QUALIFIED PER-
SONNEL ONLY . T O AVOID PERSONAL INJURY,
DO
NOT PERFORM
ANY SERVICING
OTHER THAN THAT
CONTAINED IN OPERATING INSTRUCTIONS
UNLESS YOUARE
QUALIFIED TO DOSO .
SECTION 3

THEORY OF OPERATION
Block Diagram Description ................ .......,..,,,,. . .
3-1
Detailed Circuit Description .............. ................ , ,

3-1
Main Trigger Generator ............... ............... ,,,

3-1
Delaying Sweep Generator ............. ....... . . ..... ....

3-3
Delayed Trigger Generator ............. ....... . . .,,,, .,.
3-4
Delayed
Sweep Generator

............ ........ , . ,,,,. .,,,

3-6
Horizontal Logic ................. . . ..... . . . . . ..... ...,
3-6
Output Amplifier

................
. . . .... . . .... .... .....

3-7
Readout . .
. . . .........................
..............
3-7

SECTION 4

MAINTENANCE

Page
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 .............. ............. ... 4-6
Troubleshooting Techniques

.............. ............. . .

4-6
Corrective Maintenance .................... ........ . .... . .

4-8
Obtaining Replacement Parts .............. ............. . .

4-8
Soldering Techniques

................... .............. .

4-8
Component Removal and Replacement ....... .............. . 4-9
Adjustment After Repair .................. ....... . ...... .

4-11
Repackaging For Shipment

............... .... . ......... .

4-11
SECTION 5

PERFORMANCE
CHECK/CALIBRATION
Preliminary Information ... . ................. . . . . . . . . ....

5-1
Test Equipment Required . ... .................... . . . . ....

5-1
Part I Performance Check

. . ... ..................... . . .....

5-4
Outline for Part I Performance Check

.................. .....

5-6
A
.
Trigger Sensitivity . ..... ... . ................... ....

5-4
B .
Horizontal System
. .... ......................... ... 5-4
Preliminary Procedure ....... ... . .................... ... 5-4
A . Trigger Sensitivity . ....... ........................ ...

5-5
B . Horizontal System . . . . .... . . ...................... ...

5-10
Part II Calibration

....... . .... . . . . ................... .... 5-16
Outline for Part
II Calibration

. . . . . . . . ................. ....

5-16
A . Trigger Sensitivity (SN 8070000-above) ............... ...

5-16
B . Trigger Sensitivity (SN ~069999-below) ................ . .

5-16
C . Horizontal System . ........... ................... . . 5-17
Preliminary Procedure . .......... ................... . .

5-17
A . Trigger
Sensitivity (SN ~070000-above) . . ................. .

5-18
B . Trigger Sensitivity (SN ~069999-below) . . ................. .

5-25
C . Horizontal System ................ .................. . 5-33
SECTION 6

OPTIONS
SECTION 7

REPLACEABLE ELECTRICAL
PARTS
SECTION 8

DIAGRAMS AND CIRCUIT BOARD ILLUSTRATIONS
SECTION 9

REPLACEABLE MECHANICAL PARTS
Change Information
TS (coot)

REV APR
1984
L .I ~°
Figure No .

Page
Frontispiece

7B92A Dual Time Base
1-1

Location of Variable and Mainframe Selector multi-pin connectors .

......

1-1
1-2

Location of release latch . . . . . . . . . . . ..........................

1-2
1-3

Front-panel controls and connectors .

...........................

1-3
1-4

Effect
of
MAIN TRIGGERING LEVEL and
SLOPE
controls
on
crt
display . . .

1-11
1-5

Area of graticule used for most accurate time measurements .

..........

1-12
1-6

Typical alternate sweep display .

. . . . ...........................

1-13
2-1

Dimensional drawing .

........ . . . ........................... 2-5
4-1

Lubrication procedure for a typical cam switch .

....................

4-2
4-2

Semiconductor lead configurations .

. . . ........................ .

4-4
4-3

Inter-board multi-pin connector assembly . ....................... .

4-5
4-4

End-lead multi-pin connector assembly .

........................ .

4-5
4-5

Location of pin numbers of Interface connector .

.................. .

4-5
5-1

Main Triggering level range . . ................................ .

5-6
5-2

Delayed Triggering level range .

.............................. . 5-6
5-3

Variable Time/Division range . .................................

5-13
5-4

Fast delay time accuracy . . ............................... . . . .

5-14
5-4A

AC
HF
REJ Balance ......... . . . ................... ..... ........ ....
5-19
5-5

DC
balance . (Circle denotes correct trigger point .) ..................

5-19
5-6

Trigger Sensitivity . (Circle denotes correct trigger point .)

.............

5-19
5-7

Main Triggering level range . (Circle denotes triggering limits .)

.........

5-19
5-8

Delayed Triggering level range . (Circle denotes triggering limits .)

.......

5-21
5-9

DC balance . (Circle denotes correct trigger point .) ... ...............

5-26
5-10

Trigger sensitivity
.
(Circle denotes correct trigger
point .)

.............

5-26
5-11

Main Triggering level range . (Circle denotes triggering limits .)

.........

5-27
5-12

Delayed Triggering level range . (Circle denotes triggering limits .)

.......

5-29
5-13

Correct DTM Scale and Delay Start adjustment (circle) .

..............

5-34
5-14

Variable Time/Division range . ................. ................

5-38
5-15

Fast delay time accuracy . .................... ................

5-39

7B92A
Figure
No .
LIST
OF
ILLUSTRATIONS
(cont)
The
illustrations
in
Section 8 are located near
their
associated diagrams on
the foldout pages .
8-1

Circuit board locations
8-2

Block diagram
8-3

A3 Coupling Switch circuit board
8-4

A5 Delayed Triggering Switch circuit board
8-5

A2 Source Switch circuit board
8-6

A4 Mode Switch circuit board
8-7

A1 External Input circuit board
8-8

A8 Main Trigger circuit board (SN 8070000-above)
8-9

A8 Main Trigger circuit board (SN 8069999-below)
8-10

A9 Delayed
Trigger
circuit board (SN B096951-above)
8-11

A9 Delayed
Trigger
circuit board (SN 870000-B096950)
8-12

A9 Delayed Trigger circuit board (SN 8069999-below)
8-13

A6 Interface circuit board (SN B095741-above)
8-14

A6
Interface circuit
board (SN
8095740-below)
8-15

A7 Logic circuit board (SN 8059999-below)
8-16

A7 Logic circuit board (SN 8060000-above)
8-17

A12 Readout circuit board
8-18

Location of Sweep Timing adjustments
8-19

Location of Main Trigger adjustments (SN 8069999-below)
8-20

Location of Delayed Trigger adjustments (SN 8069999-below)
8-21

Location of Main Trigger adjustments (SN B070000-above)
8-22

Location of Delayed Trigger adjustments (SN 8070000-above)

This manual contains safety information that 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
.
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 couldcause 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 infernal
adjustments must be referred to qualified
service personnel .
Do
Not Service orAdjust Alone
Do
not service or make internal adjustments
to this instrument unless another person,
capable
of giving first aid and resuscitation, 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 theinstrument 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 .

7B92A
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DUAL
TIME BASE
7B92A

OPERATING
INSTRUCTIONS
INTRODUCTION

INSTALLATION
The
7B92A Dual Time Base unit
provides normal,

The 7B92A is designed
to operate in the horizontal
delayed,
intensified, and alternate sweep operation
for

plug-in compartment of the oscilloscope . This instrument
TEKTRONIX

7000-Series

Oscilloscopes .

Calibrated

can also be installed in a vertical plug-in compartment to
sweep rates from
0 .2 second to 0 .5 nanosecond and

provide a
vertical sweep on the crt . However, when used in
triggering
to 500 megahertz are provided . The 7B92A is

this manner,
there are no internal triggering or retrace
intended for
use
with
high-frequency 7000-Series

blanking
provisions, and the unit may not meet the
Oscilloscope systems ; however,
most 7B92A functions

specifications given in the
Specification section of this
are compatible with all 7000-Series Oscilloscopes
.

manual .
Other features include lighted
pushbutton switches,

Before proceeding with installation, check the
settings
compatibility

with

indicator
oscilloscopes

having

an

of the
Time/Div Variable Selectormulti-pin
connector and
alphanumeric readout system, and 0 to 9
.8
times
con-

the Mainframe
Selector multi-pin
connector (see Fig . 1-1 ) .
tinuous
sweep delay . A VARIABLE control allows con-

The Time/Div
Variable Selector determines whether
the
tinuously
variable sweep rates between calibrated steps .

front-panel Time/Div VARIABLE
control operates in con-
Also, when operating in
the AUTO MAIN TRIGGERING

junction with the delaying or
delayed sweeps . The Main-
Mode, a bright base line
is displayed in the absence of a

frame Selector adapts the
7B92A to the oscilloscope
trigger signal .

mainframe being used . The two
mainframe selections are :
This section
describes the operation of the front-panel
controls and
connectors, and provides a functional check
and general operating information
for this instrument .
REV B, JUN 1978
NOTE
The ALT OFF position,
which allows fhe lnfensified
mode of operation, is
applicable to instruments SN
8060000-ab o ve .
1 . 7800 and
7900-Series Oscilloscopes .
2
.
All other 7000-Series Oscilloscopes
.
NO TE
The 7871 will not
delay the 7892A for displaying
alternating Delaying
and Delayed sweeps . lnsfead, it
causes a sweep lock-up to
occurunder the following
conditions ;
with the 7871 in the A
horizontal com-
Fig . 1-1 . Location of Variable
and Mainframe Selector multi-pin
connectors .
Section 1-7B92A
i~s2-oz

Operating Instructions-7B92A
To install the 7B92A in a plug-in compartment, push
it
in until it fits firmly into the compartment .
The front panel
of the 7B92A should be flush
with the front panel of the
oscilloscope . Eventhough
the gain of the oscilloscope is
standardized,
the sweep calibration of the 7B92A should
be
checked when installed . The procedure for checking
the unit is given under Sweep Calibration in the
Operating
Checkout procedure in this section .
To remove the 7B92A, pull the release latch (see
Fig .
1-2) to disengagethe unit from the oscilloscope,
and pull it
out of the plug-in compartment .
partmentandthe7B92AintheBhorizontalcompart-

shows
the Time/Div Variable and Mainframe Selectors .
meni, the sweep locks up if the 7B92A is in its

Fig . 1-3 shows the front-panel controls, connectors,
and
Alternate mode and the Mainframe
Horizontal mode

i ndicators .
i s Alf . Lock-up can be avoided by
changing the
Mainframe
Horizontal mode to Chop or B . This
allows both 7B92A
sweeps to be displayed .
RELEASE
LATCH

t X52-t s
Fig .
1-2
.
Location of release latch .
MAIN TRIGGERING Controls
LEVEL Control
Selects amplitude point on trigger signal where
sweep triggering occurs
when the MAIN
TRIGGERING MODE AUTO,
NORM,
or
SINGLE
SWEEP switches are pressed . When the MAIN
TRIGGERING MODE HF SYNC switch is pressed,
the LEVEL control adjusts the frequency of the
trigger generator to
synchronize with the frequency
(or sub-harmonic) of the
triggering signal to provide
a
stable display .
SLOPE Control
Permits triggering on the positive or
negative slope
of the trigger signal (except in HF
SYNC)
.
O
TRIG'D Indicator
When lit,
indicates that the sweep is triggered and
will produce a display with correct setting of the
POSITION control and the controls on the
associated amplifier plug-in units) and os-
cilloscope .
MODE Switches
Select the desired MAIN TRIGGERING mode .
Selected mode is indicated
by lighted pushbutton .
AUTO :
Selects a triggered sweep initiated by the
applied trigger signal at a point determined by the
LEVEL control and SLOPE control when the trigger
signal repetition rate is above30
hertz and within the
frequency
range selected by the COUPLING
switches .
When the LEVEL control is outside the
amplitude range, the trigger repetition rate is outside
the frequency range selected by the COUPLING
switches, or the trigger signal is inadequate, the
sweep free-runs to provide a reference
trace .
FRONT-PANEL CONTROLS,
CONNECTORS, AND INDICATORS

HFSYNC
:
sweep initiated by trigger signals with
repetition rates above 100 megahertz and within the
All controls, connectors, and indicators required forthe

range selected by the COUPLING
switch . Stable
operation of the 7B92A, except the Time/Div Variable and

display can be obtained when the
LEVEL control
Mainframe Selectors, are located on the
front panel . A

adjusts the frequency of the
trigger generator to the
brief description of
the front-panel controls, connectors,

frequency (or sub-harmonic) of the trigger signal .
and indicators is given here . More detailed information is

When the LEVEL control is adjusted to frequencies
given under
General Operating Information . Fig . 1-1

between sub-harmonics, the sweep free-runs .
REV B, JUN 1978

REV
B, JUN 1978
POSITION
iRIG .D

,MAIN
TRIGGERIN
/EL
MODE COUPLIR6
SOURCE
0
H f S1'~C

AC
Lf
REJ

UNf
a~ a
EIORY

AC NF
REJ
RESET
CRRTRAST

V<'~tiaFiL~
WALIN
\

TIME/DIV OR DLY TIME
tJW ~
~`~
1f

y . ' E1J
k
i
t OR
O~~O
.
.W
s

.e
i

~ .5

1
r" .
RRRRCE
Fig . 1-3
. Front-panel controls and
connectors .
_
AC INT
IN _
lp
DC ~` EXT ,
OU

YT
19
u
LEVEL
.

0
DLY'D TRIG III

REAIII TRIG III
\

aUT 5SQ

.

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
L
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DELATTIRIE

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_
TEKTRONIX®
4Y 
DUAL TIME
BASE

YY
7B92A
Operating Instructions-7B92A
1752-17
NORM :
Sweep initiated by the applied trigger
signal

a trigger is received and the
sweep is completed . The
at a point
selected by the LEVEL control and
SLOPE

SINGLE SWEEP-RESET
switch must be pressed
control
over the frequency range selected by the

again before another
sweep can be displayed .
COUPLING switches
. Triggered sweep can be ob-
tained only over the amplitude range
of the applied
trigger signal . When the
LEVEL control is either
outside the amplitude range,
the trigger repetition

O
COUPLING Switches
rate is outside the frequency range selected by the
COUPLING switches,
or the trigger signal is inade-

Select trigger signal coupling .
Selected coupling is
quate, there is no trace .

indicated
by
lighted
pushbutton .
SINGLE SWEEP-RESET :
When the SINGLE
SWEEP-RESET switch is pressed, a single
trace will

AC : Rejects do and attenuates
ac
signals
below
be presented
when thenext trigger pulse is received
.

about 30
hertz . Accepts signals between 30 hertz
The
SINGLE SWEEP-RESET switch remains lit
until

and 500 megahertz .