Tektronix 2445 User manual

Tektronix
2445
OSCILLOSCOPE
SERVICE
INSTRUCTION MANUAL

Tektronix
COMMITTED TO EXCELLENCE
WARNING
T E FOLLOWING SERVICING INSTRUCTIONS
ARE FOR USE BY QUALIFIED PERSONNEL ONLY.
TO AVOID PERSONAL INJURY, DO NOT
PERFORM ANY SERVICING OT ER T AN T AT
CONTAINED IN OPERATING INSTRUCTIONS
UNLESS YOU ARE QUALIFIED TO DO SO. REFER
TO OPERATORS SAFETY SUMMARY AND
SERVICE SAFETY SUMMARY PRIOR TO
PERFORMING ANY SERVICE.
PLEASE C ECK FOR C ANGE INFORMATION
AT T E REAR OF T IS MANUAL.
2445
OSCILLOSCOPE
SERVICE
INSTRUCTION MANUAL
Tektronix, Inc.
P.O. Box 500
Beaverton, Oregon 97077 Serial Number _ ____________________
070-3829-00
Product Group 38 First Printing JAN 1983

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.

2445 Service
TABLE OF CONTENTS
Page
LiST OF ILLUSTRATIONS ........................................... iv
LIST OF TABLES..............................................................v
OPERATORS SAFETY SUMMARY..............................vi
SERVICING SAFETY SUMMARY ................................ vii
SECTION 1 SPECIFICATION
INTRODUCTION..................................1-1
PERFORMANCE CONDITIONS .. . 1-1
SECTION 2 OPERATING INFORMATION
PREPARATION FOR USE ....................... 2-1
SAFETY CONSIDERATIONS .......... 2-1
LINE VOLTAGE SELECTION .... 2-1
Page
OPERATOR'S C ECKS
AND ADJUSTMENTS ............................... 2-17
INTRODUCTION ................................. 2-17
INITIAL SETUP .................................... 2-17
TRACE ROTATION
ADJUSTMENT ...................................... 2-17
ASTIGMATISM ADJUSTMENT . . . 2-18
AUTO DC BALANCE
ADJUSTMENT ...................................... 2-18
PROBE LOW-FREQUENCY
COMPENSATION ................................. 2-18
MATC ING C ANNEL 2
DELAY ................................................... 2-19
AMPLITUDE C ECK .......................... 2-20
TIMING C ECK .................................... 2-20
SECTION 3 T EORY OF OPERATION
LINE FUSE ........................................ 2-1
POWER CORD ................................... 2-1
INSTRUMENT COOLING ............... 2-2
START-UP...........................................2-2
REPACKAGING FOR
S IPMENT ........................................ 2-2
CONTROLS, CONNECTORS,
AND INDICATORS.................................2-4
POWER AND DISPLAY .................... 2-4
VERTICAL ........................................ 2-5
ORIZONTAL AND DELTA
MEASUREMENT .............................. 2-7
TRIGGER...........................................2-10
REAR PANEL ................................... 2-12
READOUT DISPLAY.......................2-13
OPERATING CONSIDERATIONS. . . . 2-15
GRATICULE......................................2-15
TIME AND VOLTAGE
MEASUREMENTS............................2-15
GROUNDING ................................... 2-15
SIGNAL CONNECTIONS..................2-16
INPUT-COUPLING
CAPACITOR PREC ARGING .... 2-16
EXTERNALTRIGGERING.............2-16
INTRODUCTION ................................... 3-1
SECTION ORGANIZATION ............. 3-1
YBRID AND INTEGRATED
CIRCUIT DESCRIPTIONS ............... 3-1
BLOCK DIAGRAM............................3-1
BLOCK DESCRIPTION .................... 3-1
DETAILED CIRCUIT
DESCRIPTION ........................................ 3-5
INTRODUCTION .............................. 3-5
PROCESSOR AND DIGITAL
CONTROL...........................................3-5
ANALOG CONTROL.......................3-9
FRONT-PANEL CONTROLS .......... 3-12
ATTENUATORS AND
PREAMPLIFIERS .............................. 3-14
DISPLAY SEQUENCER,
TRIGGERS, AND SWEEPS ............... 3-17
VERTICAL C ANNEL SWITC
AND OUTPUT AMPLIFIERS .......... 3-23
READOUT .... ....... 3-27
IG VOLTAGE POWER
SUPPLY AND CRT............................3-35
LOW VOLTAGE POWER
SUPPLY ............................................. 3-40

2445 Service
TABLE OF CONTENTS (cont)
Page
SECTION 3 T EORY OF OPERATION (cont)
LOW VOLTAGE
REGULATORS....................................3-45
POWER DISTRIBUTION ..................... 3-47
INTERCONNECTIONS ....................... 3-47
SECTION 4 PERFORMANCE C ECK AND
FUNCTIONAL VERIFICATION
PROCEDURE
INTRODUCTION ................................... 4-1
PREPARATION ......................... .. 4-1
VERTICAL..............................................4-4
TRIGGERING.........................................4-14
ORIZONTAL ........................................... 4-18
CALIBRATOR, EXTERNAL
Z-AXIS AND GATE OUTPUTS.............4-26
ADDITIONAL FUNCTIONAL
VERIFICATION......................................4-28
SECTION 5 ADJUSTMENT PROCEDURE
INTRODUCTION ................................... 5-1
PARTIAL PROCEDURES ............... 5-1
POWER SUPPLIES.................................5-2
CRT ADJUSTMENTS .................... .. 5-4
DAC REF, C 1 AND C 2
INPUT CAPACITANCE, AND
VERTICAL READOUT JITTER
ADJUSTMENTS ...................................... 5-7
AUTOMATIC CALIBRATION
CONSTANTS, ORIZONTAL
AND VERTICAL GAIN,
CENTERING, AND TRANSIENT
RESPONSE ADJUSTMENTS ............... 5-9
CAL 01— ORIZONTAL .................. 5-9
CAL 02-VERTICAL ......................... 5-12
CAL 03-TRIGGERING ....................... 5-14
CAL 04—C 2 DELAY
ENABLE/DiSABLE.
. ......................... 5-15
Page
DYNAMIC CENTERING,
CRT TERMINATION,
VERTICAL GAIN,
VERTICAL CENTERING,
TRANSIENT RESPONSE, F ADJ,
READOUT JITTER,
DC BALANCE, AND
X-Y P ASE DIFFERENTIAL
ADJUSTMENTS.........................................5-16
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.................................6-4
SEMICONDUCTOR C ECKS .......... 6-4
PERIODIC READJUSTMENT .......... 6-4
TROUBLES OOTING............................6-5
INTRODUCTION .............................. 6-5
TROUBLES OOTING A ID S .......... 6-5
TROUBLES OOTING
EQUIPMENT......................................6-6
TROUBLES OOTING
TEC NIQUES ................................... 6-6
DIAGNOSTIC ROUTINES ............... 6-9
CORRECTIVE MAINTENANCE .......... 6-18
INTRODUCTION ................................. 6-18
MAINTENANCE
PRECAUTIONS....................................6-18
OBTAINING REPLACEMENT
PARTS...................................................6-18
MAINTENANCE A ID S ....................... 6-18
INTERCONNECTIONS ....................... 6-19
TRANSISTORS, INTEGRATED
CIRCUITS, AND YBRID
CIRCUITS..............................................6-20
SOLDERING TEC NIQUES.............6-20
REMOVAL AND
REPLACEMENT
INSTRUCTIONS.................. .. ............ 6-22

2445 Service
TABLE OF CONTENTS (cont)
SECTION 7 OPTIONS
INTRODUCTION ..........
OPTION 2 2 ....................
OPTION 1 R ....................
POWER CORD OPTIONS
FUTURE OPTIONS. . . .
Page
SECTION 8 REPLACEABLE ELECTRICAL PARTS
, „ SECTION 9 DIAGRAMS
7-1
71 SECTION 10 REPLACEABLE MEC ANICAL PARTS
71 ACCESSORIES
7-1
7-2 C ANGE INFORMATION

2445 Service
LIST OF ILLUSTRATIONS
Figure Pa9e
The 2445 Oscilloscope .................................................................................................................... v'*i
2-1 Line selector switch, line fuse, and detachable power cord...........................................................2-2
2-2 Power and display controls.............................................................................................................2-4
2-3 Vertical controls and C 1 OR X and C 2 connectors.................................................................2-5
2-4 Channel 3 and Channel 4 controls and connectors and CALIBRATOR o u tput ....................... 2-6
2-5 orizontal and delta measurement controls..................................................................................2-7
2-6 Trigger controls and indicators...........................................................................................................2-10
2-7 Rear-panel controls and connectors....................................................................................................2-13
2-8 Readout display locations...................................................................................................................2-14
2-9 Graticule measurement markings......................................................................................................2-15
2- 10 Probe low-frequency compensation....................................................................................................2-19
3- 1 Block diagram....................................................................................................................................3-2
3-2 Address decoding............................................................................................................................ 3-7
3-3 Accept address tim ing.....................................................................................................................3-11
3-4 Front-Panel Switch m a trix.................................................................................................................3-13
3-5 Scale Illumination circu it...................................................................................................................3-17
3-6 Sweep generator..................................................................................................................................3-22
3-7 Developing the readout display.........................................................................................................3-28
3-8 Readout display priorities................................................................................................................... 3-32
3-9 Timing of Refresh Prioritizer..............................................................................................................3-33
3-10 Dc Restorer circ u it.............................................................................................................................3-38
3-11 Timing relationships of the Inverter Drive signals.............................................................................3-41
3-12 Simplified schematic of control network..........................................................................................3-42
6-1 Multipin connector orientation......................................................................................................6-6
6-2 Rear panel removal..............................................................................................................................6-23
6-3 Ribbon cable removal...........................................................................................................................6-24
9-1 Color codes for resistors and capacitors.
9-2 Semiconductor lead configurations.
9 3 Locating components on schematic diagrams and circuit board Illustration',
9-4 2445 block diagram.
9-5 A5—Control board.
9-6 A6—Front Panel and A7—Front Panel Variable boards.
9-7 Circuit view of A6—Front Panel.
9-8 A1—Main and A8—Scale Illumination boards.
9-9 A14—Dynamic Centering board.
9-10 A4— Readout board.
9-11 A9— igh Voltage board.
9-12 A2—Regulator and A3—Inverter boards,
9-13 A10—Fan Motor board.

2445 Service
LIST OF TABLES
Table Page
1-1 Electrical Characteristics.................................................................................................................. 1-2
1-2 Environmental Characteristics........................................................................................................ i-1u
1- 3 Mechanical Characteristics................................................................................................................ 1-11
2- 1 Voltage, Fuse, and Power-Cord Data..............................................................................................2-3
3- 1 Intensity Control...............................................................................................................................3-20
3-2 Trigger Source Selection.....................................................................................................................3-21
3-3 Vertical Display Selection................................................................................................................3-24
3-4 orizontal Display Selection...........................................................................................................3-25
3-5 Blanking and Intensity Control Selection.......................................................................................3-26
3-6 Readout Display Mode Selection...................................................................................................... 3-31
3- 7 Operation of Prioritizer Shift Register .............................................................................................. 3-32
4- 1 Test Equipment Required...................................................... .. . . . . . . ..................................... 4-2
4-2 Accuracy Limits (vertical)................................................................................................................4-7
4-3 C 3 and C 4 Accuracy Limits......................................................................................................4-8
4-4 C 1 or C 2 Triggering Conditions.................................................................................................4-15
4-5 C 3 or C 4 Triggering Conditions.................................................................................................4-15
4-6 Settings for A and B Timing Accuracy Checks and A Cursor Accuracy Limits ............................. 4-20
4-7 orizontal Timing Accuracy Checked Against the Graticule.........................................................4-21
4-8 Delta Time Display Accuracy..............................................................................................................4-22
4- 9 Delayed Sweep Delta Time Accuracy...............................................................................................4-23
5- 1 Power Supply Voltage and Ripple Tolerances...............................................................................5-3
5-2 orizontal Timing................................................................................................................................5-11
5-3 orizontal Timing................................................................................................................................5-12
5-4 Vertical Calibration Signals.................................................................................................................5-13
5- 5 Vertical Calibration Signals.................................................................................................................5-13
6- 1 Susceptibility to Static Discharge Damage....................................................................................6-1
6-2 External Inspection Check L is t......................................................................................................6-2
6-3 Internal Inspection Check List.........................................................................................................6-3
6-4 Sequence of Diagnostic Tests and Exerciser Routines.......................................................................6-11
6-5 Kernel Test Failure Codes...................................................................................................................6-13
6-6 Front-Panel LED Option Codes.........................................................................................................6-13
6-7 Front-Panel LED Device Codes.........................................................................................................6-13
6-8 Potentiometer Code Numbers............................................................................................................6-15
6-9 DAC Multiplexer "D " Codes..............................................................................................................6-15
6-10 Pots and Switches Column and Row Code Definitions.....................................................................6-16
6-11 Maintenance A ids................................................................................................................................6-19
V

2445 Service
OPERATORS SAFETY SUMMARY
The general safety information in this part of the summary is for both 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 jn damage to the equipment or other
property.
WARNING statements identify conditions or practices
that could result in personal injury or loss of life.
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 con
necting 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.
Terms as Marked on Equipment
CAUTION indicates a personal injury hazard not imme
diately accessible as one reads the markings, or a hazard to
property, including the equipment itself.
DANGER indicates a personal injury hazard immediately
accessible as one reads the marking.
Danger Arising From Loss of Ground
Upon loss of the protective-ground connection, all acces
sible conductive parts (including knobs and controls that
may appear to be insulating) can render an electric shock.
Symbols in This Manual
This symbol indicates where applicable
A cautionary or other information is to be
found. For maximum input voltage see
Table 1-1.
Symbols as Marked on Equipment
*DANGER — igh 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 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 Table 2-1.
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
explosive atmosphere unless it has been specifically cer
tified 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.

2445 Service
SERVICING SAFETY SUMMARY
FOR QUALIFIED SERVICE PERSONNEL ONLY
Refer also to the preceding Operators Safety Summary.
Do Not Service Alone
Do not perform internal service or adjustment of this
product 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 connec
tions or components while power is on.
Disconnect power before removing protective panels,
soldering, 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 conductor in the power cord is essential for
safe operation.