Tektronix 7704A User manual

genase
Tektronix, Inc.
P.O. Box 500
Beaverton, Oregon 97005
070-1260-00
TEKTRONIX
INSTRUCTION MANUAL
Serial Number
locce 3s
373

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Contents of this publication may not be reproduced in any
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SECTION 1
SECTION 2
SECTION 3
TABLE OF CONTENTS
TABLE OF CONTENTS
LIST OF ILLUSTRATIONS
LIST OF TABLES
OPERATING INFORMATION
PRELIMINARY INFORMATION
Operating Voltage
CONTROLS AND CONNECTORS
CIRCUIT DESCRIPTION
BLOCK DIAGRAM
Block Diagram Description
CIRCUIT OPERATION
LOGIC FUNDAMENTALS
Symbols
Logic Polarity
Input/Output Tables
Non-Digital Devices
CALIBRATOR AND ERONT PANEL <1»
MAIN INTERFACE
LOGIC CIRCUIT
TRIGGER SELECTOR
VERTICAL INTERFACE
HORIZONTAL INTERFACE
OUTPUT SIGNALS
INVERTER/RECTIFIERS<8>
LOW-VOLTAGE REGU ATORS>
READOUT SYSTEM oS
MAIN INTERCONNEC
VERTICAL AMPLIFIER
HORIZONTAL AMPLIFIER
CRT CIRCUIT
MAINTENANCE
Panel Removal
Power-Unit Removal
PREVENTIVE MAINTENANCE
Cleaning
Lubrication
Visual Inspection
Semiconductor Checks
Recalibration
TROUBLESHOOTING
Troubleshooting Equipment
Troubleshooting Techniques
7704A Service
Page
1-1
1-1
2-1
2-1
2-3
2-3
2-3
2-3
2-6
2-7
2-9
2-25
2-28
2-30
2-31
2-33
2-37
2-39
2-55
2-57
2-58
2-59
3-1
3-1
3-2
3-2
3-2
3-2
3-2
3-3
3-3

7704A Service
TABLE OF CONTENTS (cont)
Page
Special Adjustment Procedures 3-5
CORRECTIVE MAINTENANCE
Soldering Techniques 3-10
Component Replacement 3-10
Recalibration After Repair 3-19
Instrument Repackaging 3-19
SECTION 4 CALIBRATION
Calibration Interval 4-1
Tektronix Field Services 4-1
Using This Procedure 4-1
TEST EQUIPMENT REQUIRED 4-1
Special Calibration Fixtures 4-1
Calibration Equipment Alternatives 4-1
Signal Connections 4-2
CALIBRATION PROCEDURE
Index to Calibration Procedure 4-3
Preliminary Procedure for Calibration 4-4
POWER SUPPLY 4-5
Z-AXIS AND DISPLAY 4-7
VERTICAL SYSTEM 4-10
TRIGGERING 4-14
HORIZONTAL SYSTEM 4-16
CALIBRATOR 4-19
OUTPUT SIGNALS 4-21
READOUT SYSTEM 4-23
SECTION 5 ELECTRICAL PARTS LIST
SECTION 6 DIAGRAMS AND CIRCUIT BOARD ILLUSTRATIONS
Symbols and Reference Designators
SECTION 7 MECHANICAL PARTS LIST
CHANGE INFORMATION

Number
1-1
1-2A
1-2B
2-1
2-2
2-3
2-4
2-6
2-7
aoe
/ 28
2-9
2-10
2-11
2-12
2-17
2-18
2-20
) 2-21
7704A Service
LIST OF ILLUSTRATIONS
Frontispiece
Line Selector assembly on rear panel! (shown with
cover and fuses removed).
7704A front-panel controls and connectors.
7704A rear-panel controls and connectors.
7704A block diagram.
Calibrator circuit detailed block diagram.
Block diagram of Logic Circuit.
Breakdown of separate stages within Horizontal
Logic IC (U2573) showing inputs and outputs for
each stage.
(A) Logic diagram for A Sweep Lockout stage; (B)
Table of input/output combinations.
(A) Logic diagram for B Sweep Lockout stage; (B)
Table of input/output combinations.
(A) Logic diagram for Alternate Pulse Generator
stage; (B) Table of input/output combinations.
Input and output pins for Z-Axis Logic IC.
(A) Logic diagram for Z-Axis Logic stage; (B)
Table of input/output combinations.
(A) Logic diagram for Horizontal Binary stage; (B)
Table of input/output combinations.
Input and output pins for Vertical Binary IC.
(A) Logic diagram for Vertical Binary stage; (B)
Table of input/output combinations.
Input and output pins for Plug-In Binary IC.
(A) Logic diagram for Plug-In Binary stage; (B)
Table of input/output combinations.
(A) Diagram of Clock Generator stage; (B) Ide-
alized waveforms for Clock Generator stage.
(A) Logic diagram for Vertical Chopped Blanking
stage; (B) Table of input/output combinations.
Idealized waveforms for Vertical Chopped Blank-
ing stage. ,
(A) Logic diagram for Chop Counter stage; (B)
Table of input/output combinations.
Logic diagram of Vertical Mode Logic stage.
Simplified schematic of trigger selection circuitry.
Input levels at pin 4 of U2404 and U2424 (source
of triggering signal is shown in parentheses).
Page
1-1
2-12
2-13
2-14
2-16
2-17
2-18
2-19
2-20
2-23
2-24
2-25
2-26
2-27
Number
2-22
2-23
2-24
2-25
2-27
2-28
2-29
2-30
2-31
2-32
2-33
2-34
2-36
2-37
2-38
2-39
2-40
2-41
2-42
2-43
Input/output table for A and B Trigger Selector
stages.
Detailed block diagram of Vertical
circuit.
Interface
Input/output table for Vertical Plug-In Selector.
Input/output table for Vertical Trace Separation
stage.
Horizontal Interface circuit detailed block diagram.
Input/output table for Horizontal Plug-In Selector.
Output Signals detailed block diagram.
Detailed block diagram of
circuit.
Inverter/Rectifiers
Simplified schematic of Inverter, Regulator, and
Inverter Control stages.
Detailed block diagram of Low-Voltage Regulators
circuit.
Location of readout words on the CRT identifying
the originating plug-in and channel (one complete
frame shown, simulated readout).
Character Selection Matrix for 7704A Readout
System.
Typical readout display where only channel 1 of
the Right Vertical and B Horizontal! units is
displayed.
Detailed block diagram of Readout System.
Output waveforms of Timer stage.
Detail of output at pins 12, 13, 14, and 16 of
U3433.
Timer stage operation when Display-Skip condition
occurs,
Time relationship of the time-slot (TS) pulses
produced by U3445.
Typical encoding scheme for voltage-sensing plug-
in unit. Coding shown for deflection factor of 100
microvolts.
Ideafized current waveforms of: (A) Row analog
data, (B) Column analog data.
Block
U3401.
representation of memory sequence in
Typical output waveforms for Zeros Logic and
Memory stage operation (at pin 7 of U3401).
Page
2-27
2-28
2-29
2-30
2-30
2-31
2-32
2-34
2-35
2-38
2-40
2-41
2-42
2-43
2-45
2-45
2-46
2-47
2-49
2-50
2-52
2-54
ata

7704A Service
Number
2-44
2-45
2-46
2-47
2-48
3-1
3-2
3-6
3-7
3-3
4-1
4-2
4-3
LIST OF ILLUSTRATIONS (cont)
Readout word relating 10 possible character loca-
tions to the decimal point instructions that can be
encoded, and the resultant CRT display.
Flow chart for character generation by the Read-
out System,
Vertical Amplifier circuit detailed block diagram.
Horizontal
diagram.
Amplifier circuit detailed block
Detailed block diagram of CRT Circuit.
Power-unit securing screws.
Troubleshooting chart for 7704A.
Location of P4417 and P4418 on A44, Vertical
Amplifier board.
Location of adjustments on A22, Vertical Interface
board.
Location of P4315 and P4316 on A43, Horizontal
Output board.
Location of adjustments on A23, Horizontal Inter-
face board.
Disassembly and assembly of Display and Acquisi-
tion units.
Exploded-view drawing of a portion of the power
unit identifying several critical parts.
Waveform showing correct high-frequency com-
pensation of horizontal amplifier. Circle surrounds
compensated portion of waveform.
Typical display when checking X-Y phase shift.
Readout display with 03416 removed.
Electrode configuration for semiconductors used in
the 7704A.
Location of circuit boards in the 7704A.
A10—Calibrator circuit board.
Electrode configuration for semiconductors shown
on diagram 1.
Calibrator and Front Panel
A20—Main Interface circuit board.
Main Interface
A25—Logic circuit board.
Page
2-55
2-56
2-57
2-58
2-60
3-1
3-6
3-9
3-10
3-11
3-12
3-15
4-18
4-18
4-23
6-1
6-2
6-3
6-3
6-4
6-6
Number
6-7
6-14
6-15
©
6-16
6-17
Electrode configuration for semiconductors shown
on diagram 3.
Logie Circuit
A24—Trigger Selector circuit board.
Trigger Selector
A22—Vertical Interface circuit board (front view).
A22—Vertica!l Interface circuit board (rear view).
Vertical Interface
A23—Horizontal Interface circuit board.
Horizontal Interface
A33-—Signal Out circuit board.
Output Signals
A30—Power Supply Inverter circuit board.
A31—Rectifier and Filter circuit board.
Electrode configuration for semiconductors shown
on diagram 8.
Inverter/Rectifiers
A32—Regulator circuit board.
Electrode configuration for semiconductors shown
on diagram 9.
Low-Voltage Regulators.
A34—Readout circuit board.
Electrode configuration for semiconductors shown
on diagram 10.
Readout System
Main Interconnect
A44—Vertical Amplifier circuit board.
Vertical Amplifier
A43—Horizontal Output circuit board.
Efectrode configuration for semiconductors shown
on diagram 13.
Horizontal Amplifier
A41—Z-Axis circuit board.
A42-HV circuit board.
Page
6-9
6-10
6-10
6-21
6-23
6-24
6-27
6-28
6-28

Number
6-25
6-26
6-27
6-28
6-29
6-30
6-31
6-32
6-33
Nese!
7704A Service
LIST OF ILLUSTRATIONS (cont)
Electrode configuration for semiconductors shown
on diagram 14,
CRT Circuit.
+54-Volt test point focation on A32—Regulator
board (top of power unit).
+54-Volt adjustment, R3143, location in power
unit.
Power-supply test points and —50-Volt adjustment
locations on A32—Regulator board.
+150-Volt test point location on A43—Horizontal
Output board.
TP 4222, high-voltage test point location.
Location of Z-Axis and Display calibration adjust-
ments and test points on A41—Z-Axis board.
Location of Vertical System calibration adjust-
ments on A44—Vertical Amplifier board.
Location of high-frequency compensation adjust-
ments on A22—Vertical Interface board.
Location of Horizontal System calibration adjust-
ments on A43—Horizontal Output board.
Page
6-29
6-29
6-31
6-31
6-31
6-31
> 6-33
6-33
6-33
6-33
6-35
Number Page
6-35 Location of Calibrator adjustments on A10—Cali- 6-35
brator board.
6-36 Location of signal selector switches on A33—Out- 6-35
put Signals board.
6-37 Location of Readout System calibration adjust- 6-35
ments on A34—Readout board.
MECHANICAL PARTS LIST ILLUSTRATIONS
Number
4 D7704
2 A7704 Front
3 A7704 Rear
4 Cabinet
5 Accessories
6 Instrument Options
7 Repackaging
LIST OF TABLES
Number Page
2-1 Basic Logic Reference 2-3
2-2 Standard Readout Format 2-42
2-3 Channel Address Code 2-48
3-1 Power Supply Tolerance and Ripple 3-4
3-2 Fuse Ratings 3-19
4-1 Test Equipment 4-2
4-2 Power Supply Tolerance 4-6
4-3 High-Frequency Compensation 4-11

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7704A Oscilloscope System. ‘
INTRODUCTION
The TEKTRONIX 7704A Oscilloscope System is a
solid-state, high performance instrument designed for gen-
eral applications. (For rise time and bandwidth specifica-
tions of oscilloscope systems using the 7704A, see the
Operators manual). The system is composed of two individ-
ual units, the A7704 Acquisition Unit and the D7704
Display Unit.
The A7704 Acquisition Unit has four plug-in compart-
ments. The left pair of plug-in units is connected to the
vertical system; the right pair is connected to the horizontal
system. Electronic switching between the plug-ins con-
nected to each system allows a dual-trace vertical display or
a dual-sweep horizontal display.
7704A Service
The D7704 Display Unit features a CRT with small spot
size and high writing rate. In addition to the waveform, the
CRT can also display alpha-numeric information from the
plug-in units, such as deflection factor, sweep rate and
other encoded parameters. Standard graticule size is 8 X
10 centimeters.
DC supplies in the Acquisition Unit supply power for
the entire instrument. These supplies are regulated to assure
that performance is not affected by variations in line
voltage and frequency, or by changes in load due to the
varying power requirements of the plug-in units.

oe
sesso!
Section 1—7704A Service
OPERATING INFORMATION
PRELIMINARY INFORMATION
Operating Voltage
The 7704A can be operated from either a 115-volt ora
230-volt nominal fine voltage source. The Line Selector
assembly on the rear panel converts this instrument from
one operating voltage to the other. This assembly also
includes line fuses. Use the following procedure to obtain
correct instrument operation from the line voltage
available.
CAUTION
This instrument is designed for operation from a
power source with its neutral at or near earth
(ground) potential with a separate safety-earth
conductor. [t is not intended for operation from two
phases of a multi-phase system, or across the legs of a
single-phase, three-wire system.
1. Disconnect the instrument from the power source.
2. Loosen the two captive screws which hold the cover
onto the selector assembly; then pull to remove the cover.
3. To convert from 115-volt to 230-voit nominal! line
voltage, or vice versa, pull out the Selector switch bar (see
Fig. 1-1) and plug it back into the remaining hole. Change
the line-cord power plug to match the power-source
receptacle, or use a 115- to 230-volt adapter.
Power Cord Conductor Identification
Indicator
Tab
Captive
Screws
Selector
Switch bar
Conductor Color Alternate Color
Ungrounded (Line) Brown Black
Grounded (Neutral) Blue White
Grounding (Earthing) |Green-Yellow | Green-Yellow
4. Install the cover and tighten the captive screws.
REV.C, NOV. 1976
Fig. 1-1. Line Selector assembly on rear pane! (shown with cover
and fuses removed).
5. Before applying power to the instrument, check that
the indicator tab on the switch bar is protruding through
the correct hole for the desired line voltage range.
The 7704A is designed to be used with a three-wire AC
power system. If the three- to two-wire adapter is used to
connect this instrument to a two-wire AC power system, be
sure to connect the ground lead of the adapter to earth
(ground). Failure to complete the ground system may allow
the chassis of this instrument to be elevated above ground
potential and pose a shock hazard.
CONTROLS AND CONNECTORS
The major controls and connectors are located on the
front panel of the instrument. Several auxiliary functions
are provided on the rear panel. Figure 1-2 shows the front
and rear panels and provides brief descriptions of each
control and connector. For more detailed operating infor-
mation, refer to the 7704A Operators Manual.
1-1

Operating Information—7704A Service
ASTIG Screwdriver adjust-
ment to obtain a well-defined
display. Does not require re- FOCUS Adjustment for opti-
adjustment in normal use. mum display sharpness.
BEAM FINDER Compresses
and defocuses display within
graticule area regardless of dis-
play position or applied signal. .
INTENSITY Controls bright-
ness of the display (except the
readout portion). «
‘ | JI04A
TRACE
ROTATION
Screw-
OS
.
:
OSEIRLASCOPE.SYSTEM
.
driver
adjustment
to
align
:
oe
go
2
:
READOUT
Controls
bright-
trace
with
graticule.
:
;
:
:
a
ness
of
the
readout
portion
of
: the CRT display. Turns off the
readout system when in the
CCW detent position,
GRAT !LLUM Controls grati-
cule illumination.
CALIBRATOR Provides cali-
brated 40mV-4V, 1kHz
square-wave signals.
B TRIGGER SOURCE Selects
internal trigger source for B
HORIZ time base.
POWER (PULL)
B INTEN Controls brightness
of the trace produced by the B
HORIZ plug-in.
vertical
pl
gin
.
compart
‘AT704
AOBOSTION
UNIT
ment(s)
providing
the
vertical
.
deflection
signal.
HORIZONTAL MODE Selects
horizontal plug-in compart-
VERT TRACE SEPARATION A INTEN Controls brightness re eflecion agra
(B} Vertically positions the B of the trace produced by the .
HORIZ trace with respect to A HORIZ plug-in.
the A HORIZ trace (dual-
sweep modes only) .
A TRIGGER SOURCE Selects
internal trigger source for A
HORIZ time base.
Fig. 1-2A. 7704A front-panel controls and connectors.
1-2