Tektronix 2236 User manual

Tektronix
COMMITTED TO EXCELLENCE
WARNING
THE FOLLOWING SERVICING INSTRUCTIONS ARE
FOR USE B QUALIFIED PERSONNEL ONL . TO
AVOID PERSONAL INJUR , DO NOT PERFORM AN
SERVICING OTHER THAN THAT CONTAINED IN
OPERATING INSTRUCTIONS UNLESS OU ARE
QUALIFIED TO DO SO. REFER TO THE OPERATORS
SAFET SUMMAR AND THE SERVICE SAFET
SUMMAR PRIOR TO PERFORMING AN SERVICE.
PLEASE CHECK FOR CHANGE INFORMATION
AT THE REAR OF THIS MANUAL.
2236
OSCILLOSCOPE
SERVICE
INSTRUCTION MANUAL
Tektronix, Inc.
P.O. Box 500
Beaverton, Oregon 97077 Serial Number
070-4204-00
Product Group 46 First Printing MAR 1983
Revised NOV 1986

Copyright © 1983 Tektronix, Inc. All rights reserved.
Contents of this publication may not be reproduced in any
form without the written permission of Tektronix, Inc.
Products of Tektronix, Inc. and its subsidiaries are covered
by U.S. and foreign patents and/or pending patents.
TEKTRONIX, TEK, SCOPE-MOBILE, and are
registered trademarks of Tektronix, Inc. TELEQUIPMENT
is a registered trademark of Tektronix U.K. Limited.
Printed in U.S.A. Specification and price change privileges
are reserved.
INSTRUMENT SERIAL NUMBERS
Each instrument has a serial number on a panel insert, tag,
or stamped on the chassis. The first number or letter
designates the country of manufacture. The last five digits
of the serial number are assigned sequentially and are
unique to each instrument. Those manufactured in the
United States have six unique digits. The country of
manufacture is identified as follows:
B000000 Tektronix, Inc., Beaverton, Oregon, USA
100000 Tektronix Guernsey, Ltd., Channel Islands
200000 Tektronix United Kingdom, Ltd., London
300000 Sony/Tektronix, Japan
700000 Tektronix Holland, NV, Heerenveen,
The Netherlands

2236 Service
TABLE OF CONTENTS
Page
LIST OF ILLUSTRATIONS ...................................... iv
LIST OF TABLES ..................................................... v
OPERATORS SAFET SUMMMAR ...................... vi
SERVICING SAFET SUMMAR ............................ vii
SECTION 1 SPECIFICATION
INTRODUCTION .............................. 1-1
ACCESSORIES ................................ 1-1
PERFORMANCE CONDITIONS .... 1-1
SECTION 2 OPERATING INSTRUCTIONS
PREPARATION FOR USE .............. 2-1
SAFET ...................................... 2-1
LINE VOLTAGE .......................... 2-1
POWER CORD ............................ 2-1
LINE FUSE .................................. 2-1
INSTRUMENT COOLING ............ 2-2
CONTROLS, CONNECTORS, AND
INDICATORS .................................... 2-2
DISPLA , POWER, AND PROBE
ADJUST ...................................... 2-2
VERTICAL .................................. 2-3
HORIZONTAL .............................. 2-4
TRIGGER .................................... 2-6
COUNTER, TIMER, AND
MULTIMETER ............................ 2-8
RIGHT SIDE PANEL .................... 2-9
REAR PANEL .............................. 2-9
OPERATING CONSIDERATIONS .. . 2-11
GRATICULE ................................ 2-11
GROUNDING .............................. 2-11
SIGNAL CONNECTIONS ............ 2-11
INPUT COUPLING CAPACITOR
PRECHARGING .......................... 2-11
POWER-UP CHECKS ................ 2-12
CTM MEASUREMENT
CONSIDERATIONS .................... 2-12
STATUS AND ERRORS
MESSAGES ................................ 2-12
OPERATOR’S ADJUSTMENTS .... 2-14
INTRODUCTION ........................ 2-14
BASELINE TRACE ...................... 2-14
TRACE ROTATION ...................... 2-14
PROBE COMPENSATION .......... 2-15
Page
SECTION 3 THEOR OF OPERATION
INTRODUCTION .............................. 3-1
SECTION ORGANIZATION ........ 3-1
INTEGRATED CIRCUIT
DESCRIPTIONS .......................... 3-1
GENERAL DESCRIPTION .............. 3-2
OSCILLOSCOPE ........................ 3-2
CTM ............................................ 3-3
DETAILED CIRCUIT DESCRIPTION 3-4
OSCILLOSCOPE ........................ 3-4
VERTICAL ATTENUATORS . . 3-4
Input Coupling .................... 3-4
Buffer Amplifier and Gain
Switching Network ............ 3-5
Paraphase Amplifier .......... 3-5
VERTICAL PREAMPLIFIERS . 3-5
CHANNEL SWITCH AND
VERTICAL OUTPUT .............. 3-6
Delay Line Driver ................ 3-7
Vertical Output Amplifier ... 3-7
A/B Sweep Separation
Circuit ................................ 3-8
TRIGGER AMPLIFIERS AND
SWITCHING ............................ 3-8
Internal Trigger Amplifier ... 3-9
A External Trigger Amplifier 3-9
Line Trigger Amplifier ........ 3-9
A TRIGGER GENERATOR ... 3-9
A Trigger Level Circuit .... 3-9
A Trigger Level Comparator 3-10
A Schmitt Trigger and TV
Trigger Circuit .................... 3-10
A SWEEP GENERATOR AND
LOGIC .................................... 3-10
A Miller Sweep Generator .. 3-11
A Sweep Logic .................. 3-11
ALTERNATE B SWEEP .......... 3-12
B Miller Sweep Generator . 3-12
B Trigger Level Comparator 3-13
Runs After Delay ................ 3-13
B Delay Time Position
Comparator ........................ 3-13
B Sweep Logic .................. 3-13
Alternate Display Switching
Logic .................................. 3-14
B Z-Axis Logic .................. 3-14
i

2236 Service
SECTION 3
TABLE OF CONTENTS (cont)
Page Page
THEOR OF OPERATION (cont) SECTION 3 THEOR OF OPERATION (cont)
HORIZONTAL ........................
3-14 SCOPE SWEEP S STEM
Horizontal Preamplifier .... 3-14 INTERFACE
............................
3-28
X- Amplifier ......................
3-15 Delay/Delta Time Controller-
Horizontal Output Amplifier . 3-15 Digital Section ....................
3-28
Z-AXIS AMPLIFIER ................ 3-16 Delay/Delta Time Controller-
Dc Restorer ........................
3-17 Analog Section
..................
3-29
POWER SUPPL AND PROBE Intensified Zone Controller . 3-29
ADJUST ..................................
3-18 DMM ......................................
3-29
Power Input ........................ 3-18 Input Switching Network ... 3-32
Preregulator ...................... 3-18 Input Filter
..........................
3-33
Inverter .............................. 3-19 Input Buffer
........................
3-33
Crt Supply ..........................
3-19 Rms Converter ..................
3-34
Focus Circuit ......................
3-19 Ac Compensation
.............. 3-34
Low-Voltage Supplies and Multiplexer and Voltage
Fan ....................................
3-19 Reference
..........................
3-34
Probe Adjust ......................
3-20 V/F Converter
.................... 3-34
CTM ............................................. 3-20 Ohms Reference
................
3-35
CPU S STEM ........................ 3-20 Overload Protection
..........
3-36
Microprocessor Reset ........
3-20 Serial Interface
..................
3-36
CPU Clock and Interrupt Relay Drive
........................
3-36
Timing ................................ 3-20 DMM Power Supply
.......... 3-37
Address Decoding Logic ... 3-20
ROM ..................................
3-20
Buffered Data Bus Latch .. 3-21
Counter Data Bus Switch .. 3-21
DISPLA S STEM
Display Multiplexing ..........
3-21 SECTION 4 PERFORMANCE CHECK
Display and Filament Driver 3-21 PROCEDURE
INPUT/OUTPUT PORTS INTRODUCTION
.............................. 4-1
Sample Counter Read Ports 3-21 PURPOSE
.......... ........................ 4-1
Time Counter Read Ports .. 3-22 STRUCTURE
.............................. 4-1
Pushbutton Read Port .... 3-22 TEST EQUIPMENT
....................
4-1
Oscilloscope Read Port and LIMITS AND TOLERANCES . . . . 4-1
Probe Decoder ..................
3-22 PREPARATION FOR CHECKS .. 4-2
Counter Control Latch .... 3-22 INDEX TO PERFORMANCE
DMM Control Latch ..........
3-22 CHECK STEPS
..........................
4-4
Audio Transducer .............. 3-22 VERTICAL
........................................
4-5
COUNTER S STEM .............. 3-22 HORIZONTAL
.................................. 4-9
Input Multiplexer ................ 3-22 TRIGGER
........................................
4-12
Synchronizer ......................
3-23 C TM
.................................................. 4-15
Oscillators .......................... 3-27
Phase-Locked Loop .......... 3-27
Sample and Time Counter
Chains ................................
3-27
ii

2236 Service
TABLE OF CONTENTS (cont)
Page
SECTION 5 ADJUSTMENT PROCEDURE
INTRODUCTION .............................. 5-1
PURPOSE .................................. 5-1
STRUCTURE .............................. 5-1
TEST EQUIPMENT .................... 5-1
LIMITS AND TOLERANCES .... 5-1
ADJUSTMENT INTERACTION . . 5-1
PREPARATION FOR
ADJUSTMENT ............................ 5-1
INDEX TO ADJUSTMENT
PROCEDURE STEPS ................ 5-3
POWER SUPPL AND CRT DISPLA 5-4
VERTICAL ........................................ 5-6
HORIZONTAL .................................. 5-15
TRIGGER ......................................... 5-20
C TM ................................................... 5-24
SECTION 6 MAINTENANCE
STATIC-SENSITIVE COMPONENTS 6-1
PREVENTIVE MAINTENANCE ........ 6-2
INTRODUCTION ........................ 6-2
GENERAL CARE ........................ 6-2
INSPECTION AND CLEANING . . 6-2
LUBRICATION ............................ 6-5
SEMICONDUCTOR CHECKS ... 6-5
PERIODIC READJUSTMENT ... 6-5
TROUBLESHOOTING ...................... 6-5
INTRODUCTION ........................ 6-5
TROUBLESHOOTING AIDS .... 6-5
TROUBLESHOOTING
EQUIPMENT .............................. 6-7
TROUBLESHOOTING
TECHNIQUES ............................ 6-7
CTM TROUBLESHOOTING
PROCEDURE .............................. 6-10
CORRECTIVE MAINTENANCE ___ 6-22
INTRODUCTION ........................ 6-22
MAINTENANCE PRECAUTIONS . 6-22
Page
SECTION 6 MAINTENANCE (cont)
OBTAINING REPLACEMENT
PARTS ........................................ 6-22
MAINTENANCE AIDS ................ 6-22
INTERCONNECTIONS ................ 6-22
TRANSISTORS AND
INTEGRATED CIRCUITS .... 6-24
SOLDERING TECHNIQUES .... 6-24
REMOVAL AND REPLACEMENT
INSTRUCTIONS .......................... 6-25
Cabinet .................................... 6-25
CTM Circuit Board .................. 6-25
Display Circuit Board .............. 6-27
Cathode-Ray Tube .................. 6-28
Power-Supply Shield .............. 6-29
Filter Circuit Board .................. 6-29
Alt Sweep Circuit Board ........ 6-29
Attenuator and Logic Switch
Circuit Board .......................... 6-30
Timing Circuit Board .............. 6-31
Bottom Shield, Attenuator and
Timing Circuit-Board Module .. 6-32
Front-Panel Circuit Board .... 6-32
Main Circuit Board .................. 6-34
REPACKAGING FOR SHIPMENT 6-35
SELECTABLE COMPONENTS .. 6-36
SECTION 7 OPTIONS
SECTION 8 REPLACEABLE ELECTRICAL PARTS
SECTION 9 DIAGRAMS
SECTION 10 REPLACEABLE MECHANICAL
PARTS
ACCESSORIES
CHANGE INFORMATION

2236 Service
LIST OF ILLUSTRATIONS
Figure Page Figure Page
1-1 Maximum input voltage vs frequency 3-12 Typical waveforms for the Delay function
derating curve for CH 1 OR X & DMM, CH 2 with Valt LO
.............................................. 3-30
OR .and EXT INPUT connectors ............ 1-17 3-13 Typical waveforms for the Delta Time func-
1-2 Physical dimensions of the 2236 Oscillo- tion with Valt HI
........................................ 3-31
scope ..........................................................
1-18 3-14 Typical waveforms for the Delta Time func-
tion with Valt L O ........................................ 3-32
2-1 Optional power cords
................................
2-1
2-2 Fuse holder and power cord connector ... 2-2 4-1 Test setup for DMM common mode check . 4-21
2-3 Power and display controls and indicators
and PROBE ADJUST output .................... 2-3
2-4 Vertical controls and connectors
................ 2-3 6-1 Multi-connector holder orientation
............ 6-7
2-5 Horizontal controls
....................................
2-5 6-2 Period measurement loop test waveforms . 6-19
2-6 Trigger controls, connector, and indicator . 2-6 6-3 Width measurement loop test waveforms . 6-20
2-7 Counter, timer, and multimeter controls and 6-4 DMM serial interface loops test waveforms 6-21
indicator ......................................................
2-8
2-8 Multimeter right side panel connectors .... 2-10
2-9 Rear panel connector
................................
2-10 9-1 Color codes for resistors and capacitors
2-10 Graticule measurement markings
.............. 2-11 9-2 Semiconductor lead configurations
2-11 Probe compensation
..................................
2-15 9-3 Locating components on schematic dia-
grams and circuit board illustrations
9-4 Oscilloscope basic block diagram
3-1 Block diagram of the Vertical Attenuators . 3-4 9-5 Oscilloscope detailed block diagram
3-2 Block diagram of the Channel Switching 9-6 CTM basic block diagram
circuitry ......................................................
3-6 9-7 CTM detailed block diagram
3-3 Block diagram of the A Sweep Generator 9-8 Circuit board location illustration
and Logic circuitry ......................................
3-11 9-9 A2-Attenuator board
3-4 Block diagram of the Horizontal Amplifier . 3-15 9-10 A15-Logic Switch board
3-5 Simplified diagram of the Dc Restorer 9-11 Al-Main board
circuitry ......................................................
3-17 9-12 Circuit view of Al-Main board
3-6 Simplified diagram of the Period measure- 9-13 A3-Front Panel board
ment circuitry ..............................................
3-23 9-14 Circuit view of A3-Front Panel board
3-7 Typical waveforms for the Nongated Period 9-15 A4-Timing board
function ......................................................
3-24 9-16 A5-Altn Sweep logic board
3-8 Typical waveforms for the Gated Period 9-17 A6-Filter board
function ......................................................
3-25 9-18 A12-Multimeter Control board
3-9 Simplified diagram of the Width measure- 9-19 A10-Counter/Timer/Multimeter board
ment circuitry ..............................................
3-25 9-20 A14-Hot Signal Switch board
3-10 Typical waveforms for the Width function . 3-26 9-21 A13-Display board
3-11 Typical waveforms for the Delay function 9-22 Partial A11-Counter/Timer/Multimeter board
with Valt HI ................................................
3-29 with Option 14
iv REV JAN 1985

2236 Service
LIST OF TABLES
Table Page Table Page
1-1 Electrical Characteristics
..........................
. 1-2 5-3 Deflection Accuracy Limits
......................
. 5-9
1-2 Environmental Characteristics
....................
. 1-16 5-4 Settings for Bandwidth Checks
..............
. 5-12
1-3 Physical Characteristics
..........................
. 1-17 5-5 Settings for Timing Accuracy Checks .... . 5-17
5-6 Switch Combinations for A Triggering
2-1 VERT MODE Trigger Source
....................
. 2-7 Checks ......................................................
. 5-22
2-2 Power-up Checks
......................................
. 2-12 5-7 Dc Voltage Readout Checks
....................
. 5-27
2-3 Equipment Required for 10X Probe 5-8 Ac Voltage Readout Checks
....................
. 5-27
Compensation ............................................. 2-16 5-9 Dc Probe Readout Checks
......................
. 5-28
5-10 Ac Probe Readout Checks
......................
. 5-29
4-1 Test Equipment Required
..........................
. 4-2 5-11 Resistance Readout Checks
....................
. 5-29
4-2 Deflection Accuracy Limits
........................
. 4-5
4-3 Settings for Bandwidth Checks
..............
. 4-7
4-4 Settings for Timing Accuracy Checks .... . 4-10 6-1 Relative Susceptibility to Static-Discharge
4-5 Switch Combinations for A Triggering Damage
......................................................
. 6-1
Checks ......................................................
. 4-12 6-2 External Inspection Checklist
....................
. 6-3
4-6 Dc Voltage Readout Checks
......................
. 4-17 6-3 Internal Inspection Checklist
......................
. 6-3
4-7 Ac Voltage Readout Checks
....................
. 4-17 6-4 Power Supply Limits and Ripple
................
. 6-8
4-8 Dc CH 1 Readout Checks
........................
. 4-18 6-5 Control Switches Verification Readout . . . . 6-12
4-9 Dc Probe Readout Checks ......................
. 4-18 6-6 Channel 1 Logic Verification
....................
. 6-12
4-10 Ac.CH 1 Readout Checks
........................
. 4-18 6-7 Test 1-ROM Check Test Messages
........
. 6-13
4-11 Ac Probe Readout Checks
......................
. 4-18 6-8 Test 2-Counter Error Messages
..............
. 6-14
4-12 Resistance Readout Checks
....................
. 4-19 6-9 Test 3-DMM Test Error Codes
................
. 6-16
6-10 Test 4 Extended Counter Error Messages . 6-17
5-1 Adjustment Interactions
..........................
. 5-2 6-11 Maintenance Aids
....................................
. 6-23
5-2 Power Supply Limits
................................
. 5-4 6-12 Trigger Bandwidth Alternation
................
■ 6-36
v

2236 Service
OPERATORS SAFET SUMMAR
The general safety information in this part of the summary is for tooth operating and servicing personnel. Specific warnings and
cautions will be found throughout the manual where they apply and do not appear in this summary.
Terms in This Manual
CAUTION statements identify conditions or practices that
could result in damage to the equipment or other property.
WARNING statements identify conditions or practices that
could result in personal injury or loss of life.
Terms as Marked on Equipment
CAUTION indicates a personal injury hazard not immedi
ately accessible as one reads the markings, or a hazard to
property, including the equipment itself.
Grounding the Product
This product is grounded through the grounding conductor
of the power cord. To avoid electrical shock, plug the power
cord into a properly wired receptacle before connecting to
the product input or output terminals. A protective ground
connection by way of the grounding conductor in the power
cord is essential for safe operation.
Danger Arising From Loss of Ground
Upon loss of the protective-ground connection, all accessi
ble conductive parts (including knobs and controls that may
appear to be insulating) can render an electric shock.
DANGER indicates a personal injury hazard immediately ac
cessible as one reads the marking.
Symbols in This Manual
This symbol indicates where applicable
cautionary or other information is to be found.
For maximum input voltage see Table 1-1.
Use the Proper Power Cord
Use only the power cord and connector specified for your
product.
Use only a power cord that is in good condition.
For detailed information on power cords and connectors see
Figure 2-1.
Symbols As Marked on Equipment
DANGER — High voltage.
Protective ground (earth) terminal.
ATTENTION — Refer to manual.
Power Source
This product is intended to operate from a power source
that does not apply more than 250 volts rms between the
supply conductors or between either supply conductor and
ground. A protective ground connection by way of the
grounding conductor in the power cord is essential for safe
operation.
Use the Proper Fuse
To avoid fire hazard, use only a fuse of the correct type,
voltage rating and current rating as specified in the parts list
for your product.
Do Not Operate in Explosive Atmospheres
To avoid explosion, do not operate this product in an explo
sive atmosphere unless it has been specifically certified for
such operation.
Do Not Remove Covers or Panels
To avoid personal injury, do not remove the product covers
or panels. Do not operate the product without the covers
and panels properly installed.
vi

2236 Service
SERVICING SAFET SUMMAR
FOR Q ALIFIED SERVICE PERSONNEL ONLY
Refer also to the preceding Operators Safety Summary.
Do Not Service Alone
Do not perform internal service or adjustment of this prod
uct unless another person capable of rendering first aid and
resuscitation is present.
Use Care When Servicing With Power On
Dangerous voltages exist at several points in this product.
To avoid personal injury, do not touch exposed connections
or components while power is on.
Disconnect power before removing protective panels, sol
dering, or replacing components.
Power Source
This product is intended to operate from a power source
that does not apply more than 250 volts rms between the
supply conductors or between either supply conductor and
ground. A protective ground connection by way of the
grounding connector in the power cord is essential for safe
operation.

2236 Service
viii
The 2236 Oscilloscope.