Tektronix TDS 420A User manual

Service Manual
TDS 420A, TDS 430A & TDS 460A
Digitizing Oscilloscopes
S/N B080000 and above
070-9703-06
Revsion A
Warning
The servicing instructions are for use by qualified
personnel only. To avoid personal injury, do not
perform any servicing unless you are qualified to
do so. Refer to all safety summaries prior to
performing service.
www.tektronix.com

Copyright ©Tektronix, Inc. All rights reserved.
Tektronix products are covered by U.S. and foreign patents, issued and pending. Information in this publication supercedes
that in all previously published material. Specifications and price change privileges reserved.
Tektronix, Inc., P.O. Box 500, Beaverton, OR 97077
TEKTRONIX and TEK are registered trademarks of Tektronix, Inc.

WARRANTY
Tektronix warrants that the products that it manufactures and sells will be free from defects in materials and workmanship
for a period of three (3) years from the date of shipment. If a product proves defective during this warranty period,
Tektronix, at its option, either will repair the defective product without charge for parts and labor, or will provide a
replacement in exchange for the defective product.
In order to obtain service under this warranty, Customer must notify Tektronix of the defect before the expiration of the
warranty period and make suitable arrangements for the performance of service. Customer shall be responsible for
packaging and shipping the defective product to the service center designated by Tektronix, with shipping charges prepaid.
Tektronix shall pay for the return of the product to Customer if the shipment is to a location within the country in which the
Tektronix service center is located. Customer shall be responsible for paying all shipping charges, duties, taxes, and any
other charges for products returned to any other locations.
This warranty shall not apply to any defect, failure or damage caused by improper use or improper or inadequate
maintenance and care. Tektronix shall not be obligated to furnish service under this warranty a) to repair damage resulting
from attempts by personnel other than Tektronix representatives to install, repair or service the product; b) to repair
damage resulting from improper use or connection to incompatible equipment; c) to repair any damage or malfunction
caused by the use of non-Tektronix supplies; or d) to service a product that has been modified or integrated with other
products when the effect of such modification or integration increases the time or difficulty of servicing the product.
THIS WARRANTY IS GIVEN BY TEKTRONIX IN LIEU OF ANY OTHER WARRANTIES, EXPRESS OR
IMPLIED. TEKTRONIX AND ITS VENDORS DISCLAIM ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. TEKTRONIX’ RESPONSIBILITY TO
REPAIR OR REPLACE DEFECTIVE PRODUCTS IS THE SOLE AND EXCLUSIVE REMEDY PROVIDED TO
THE CUSTOMER FOR BREACH OF THIS WARRANTY. TEKTRONIX AND ITS VENDORS WILL NOT BE
LIABLE FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES IRRESPECTIVE
OF WHETHER TEKTRONIX OR THE VENDOR HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH
DAMAGES.

Contacting Tektronix
Phone [phone]*
Address Tektronix, Inc.
Department or name (if known)
14200 SW Karl Braun Drive
P.O. Box 500
Beaverton, OR 97077
USA
Web site www.tektronix.com
Sales support 1-800-833-9200, select option 1*
Service support 1-800-833-9200, select option 2*
Technical support Email: [e-mail]
1-800-833-9200, select option 3*
1-503-627-2400
6:00 a.m. -- 5:00 p.m. Pacific time
*This phone number is toll free in North America. After office hours, please leave a
voice mail message.
Outside North America, contact a Tektronix sales office or distributor; see the
Tektronix web site for a list of offices.

TDS 420A, TDS 430A & TDS 460A Service Manual i
Table of Contents
List of Figures iii............................................
List of Tables vi.............................................
General Safety Summary ix...................................
Service Safety Summary xi....................................
Preface xiii...................................................
Introduction xvi..............................................
Before Servicing xvi.................................................
Strategy for Servicing xvi.............................................
Tektronix Service xvii................................................
Specifications
Product Description 1--1........................................
Nominal Traits 1--7............................................
Warranted Characteristics 1--15..................................
Typical Characteristics 1--23.....................................
Operating Information
Installation 2--1...............................................
Supplying Operating Power 2--1........................................
Operating Environment 2--3...........................................
Applying and Interrupting Power 2--4....................................
Repackaging Instructions 2--5..........................................
Installed Options 2--5.................................................
Operating Information 2--7.....................................
Screen Layout 2--7...................................................
Basic Procedures 2--7.................................................
Theory of Operation
Theory of Operation 3--1.......................................
Logic Conventions 3--1...............................................
Module Overview 3--1................................................
Performance Verification
Performance Verification Procedures 4--1.........................
Brief Procedures 4--5...........................................
Self Tests 4--5.......................................................
Functional Tests 4--7.................................................
Performance Tests 4--15.........................................
Prerequisites 4--15....................................................
Equipment Required 4--16..............................................
Test Record 4--18.....................................................

Table of Contents
ii TDS 420A, TDS 430A & TDS 460A Service Manual
Signal Acquisition System Checks 4--20...................................
Time Base System Checks 4--34.........................................
Trigger System Checks 4--38............................................
Output Signal Check 4--53..............................................
Sine Wave Generator Leveling Procedure 4--55.............................
Adjustment Procedures
Adjustment Procedures 5--1.....................................
Requirements for Performance 5--1......................................
Usage 5--2.........................................................
Equipment Required 5--5..............................................
Adjustment Instructions 5--7...........................................
Probe Adjustment 5--10................................................
Monitor Assembly Adjustment 5--21.....................................
Maintenance
Maintenance 6--1..............................................
Related Maintenance Procedures 6--1....................................
Preparation 6--2.....................................................
Inspection and Cleaning 6--4...........................................
Removal and Installation Procedures 6--9.........................
Preparation — Please Read 6--9........................................
Access Procedure 6--13................................................
Procedures for Module Removal and Installation 6--23.......................
Disassembly for Cleaning 6--71..........................................
Troubleshooting 6--75...........................................
Diagnostics 6--75.....................................................
Firmware Updates 6--76................................................
Troubleshooting Equipment 6--77........................................
Options
Electrical Parts List
Diagrams
Mechanical Parts List

Table of Contents
TDS 420A, TDS 430A & TDS 460A Service Manual iii
List of Figures
Figure 1--1: TDS 400A Dimensional Drawing 1--13...................
Figure 2--1: Map of Display Functions 2--8........................
Figure 4--1: Map of Display Functions 4--3........................
Figure 4--2: Verifying Adjustments and Signal Path Compensation 4--6
Figure 4--3: Universal Test Hookup for Functional Tests 4--8.........
Figure 4--4: Initial Test Hookup 4--20..............................
Figure 4--5: Initial Test Hookup 4--23..............................
Figure 4--6: Initial Test Hookup 4--26..............................
Figure 4--7: Measurement of Analog Bandwidth 4--29................
Figure 4--8: Initial Test Hookup 4--31..............................
Figure 4--9: Measurement of Channel Delay 4--33....................
Figure 4--10: Initial Test Hookup 4--34.............................
Figure 4--11: Measurement of Accuracy — Long-Term and
Delay-Time 4--37............................................
Figure 4--12: Initial Test Hookup 4--38.............................
Figure 4--13: Initial Test Hookup 4--41.............................
Figure 4--14: Measurement of Trigger Sensitivity 4--43...............
Figure 4--15: Initial Test Hookup 4--45.............................
Figure 4--16: Confirming Auxiliary Triggering at Maximum
Triggering Frequency 4--46...................................
Figure 4--18: Initial Test Hookup 4--49.............................
Figure 4--19: Adjusting Sync Pulse Amplitude 4--51..................
Figure 4--20: Measurement of Video Sensitivity 4--52.................
Figure 4--21: Initial Test Hookup 4--54.............................
Figure 4--22: Measurement of Probe Compensator Limits 4--55........
Figure 4--23: Sine Wave Generator Leveling Equipment Setup 4--56....
Figure 4--24: Equipment Setup for maximum Amplitude 4--57.........
Figure 5--1: Hookup for Probe Compensation 5--10..................
Figure 5--2: Performing Probe Compensation 5--11..................
Figure 5--3: Proper and Improper Probe Compensation 5--12..........
Figure 5--4: Exposing the Inner Probe Tip 5--13.....................
Figure 5--5: Initial Test Hookup 5--13..............................
Figure 5--6: Exposing the Probe Body 5--16.........................

Table of Contents
iv TDS 420A, TDS 430A & TDS 460A Service Manual
Figure 5--7: Initial Test Hookup 5--16..............................
Figure 5--8: Probe Test Hookup 5--18..............................
Figure 5--9: Locations of Probe Adjustments 5--19...................
Figure 5--10: Adjustments vs. Front-Corner Response 5--20...........
Figure 5--11: Monitor Adjustment Locations 5--23...................
Figure 5--12: Five and Ten Percent Luminance Patches 5--24..........
Figure 5--13: Composite Pattern for Focusing 5--25..................
Figure 6--1: Oscilloscope Orientation 6--11..........................
Figure 6--2: Cabinet and Front-Panel Mounted Modules 6--16.........
Figure 6--3: Internal Modules 6--19................................
Figure 6--4: Cables and cable routing, B010100 -- B079999 6--22.......
Figure 6--5: Cables and cable routing, B080000 & up 6--23............
Figure 6--6: Knob and shaft removal 6--25..........................
Figure 6--7: Line fuse and line cord removal 6--26...................
Figure 6--8: Front cover, rear cover, cabinet, emi gasket,
and cabinet handle and feet removal 6--28.......................
Figure 6--9: Trim ring, menu elastomer, and menu
buttons removal 6--31........................................
Figure 6--10: EMI gasket removal and installation 6--33..............
Figure 6--11: Disk drive removal 6--34.............................
Figure 6--12: A06 Front-Panel assembly, ESD shield,
and menu flex and probe code flex circuits removal 6--36..........
Figure 6--13: Disassembly of the front-panel assembly 6--37...........
Figure 6--14: A05 Attenuator removal 6--40.........................
Figure 6--15: A26 Monitor assembly removal 6--43...................
Figure 6--16: A08 Jumper board assembly, D1 Bus,
and board supports removal 6--44.............................
Figure 6--17: A03 CPU removal 6--46..............................
Figure 6--18: A02 Display assembly removal 6--48....................
Figure 6--19: A09 DSP assembly removal 6--49......................
Figure 6--20: A01 Backplane assembly and its mount removal 6--51.....
Figure 6--21: Battery removal 6--54................................
Figure 6--22: Power factor correction module
removal, B080000 & up 6--56.................................
Figure 6--23: A24 Low voltage power supply
removal, B080000 & up 6--59.................................
Figure 6--24: A25 Low voltage power supply
removal, B010100 -- B079999 6--61.............................
Figure 6--25: Fan and fan mount removal 6--64......................

Table of Contents
TDS 420A, TDS 430A & TDS 460A Service Manual v
Figure 6--26: Line filter removal 6--65..............................
Figure 6--27: Auxiliary power supply
removal, B010100 -- B079999 6--68.............................
Figure 6--28: A04 Acquisition Board Removal 6--70..................
Figure 6--29: Accessing the protection switch 6--76...................
Figure 6--30: Console port connections 6--79........................
Figure 6--31: Primary Troubleshooting Procedure 6--80...............
Figure 6--32: A03 CPU Board Connector P1 6--81....................
Figure 6--33: Module Isolation Troubleshooting Procedure 6--82.......
Figure 6--34: Low Voltage Power Supply
Troubleshooting Procedure 6--84..............................
Figure 6--35: Power Supply Overload
Troubleshooting Procedure 6--86..............................
Figure 6--36: A25 Low Voltage Power
Supply Module (Right Side) 6--87..............................
Figure 6--37: Monitor Troubleshooting Procedure 6--88...............
Figure 6--38: Horizontal and Vertical Sync Signals 6--89..............
Figure 6--39: A Video Signal with White, Black,
and Blanking Levels 6--89....................................
Figure 6--40: A26 Monitor Connector J440 6--90.....................
Figure 6--41: A07 Auxiliary Power Connectors J4 and J7 6--90.........
Figure 6--42: A02 Display Connector J2 6--91.......................
Figure 6--43: Processor/Front Panel Troubleshooting Procedure 6--92...
Figure 6--44: A06 Front Panel Board Power Connectors
J101 and J106 6--93.........................................
Figure 6--45: Attenuator/Acquisition Troubleshooting Procedure 6--94..
Figure 6--46: A08 Jumper and A05 Attenuator Boards
Signal Locations 6--95.......................................
Figure 6--47: Acquisition and Attenuator Power
Troubleshooting Procedure 6--96..............................
Figure 6--48: A04 Acquisition Board Power Connector 6--97...........
Figure 6--49: Backplane Troubleshooting Procedure 6--98.............
Figure 6--50: A01 Backplane Module 6--100..........................
Figure 6--51: I2C Isolation Troubleshooting Procedure 6--101...........
Figure 6--52: Console Troubleshooting Procedure 6--102...............
Figure 9--1: TDS 400A Interconnections, B010100 -- B079999 9--2.....
Figure 9--2: TDS 400A Interconnections, B010100 -- B079999 (Cont) 9--3
Figure 9--3: TDS 400A Block Diagram, B010100 -- B079999 9--4.......
Figure 9--4: TDS 400A Block Diagram, B010100 -- B079999 (Cont) 9--5

Table of Contents
vi TDS 420A, TDS 430A & TDS 460A Service Manual
Figure 9--5: TDS 400A Interconnections, B080000 & up 9--6..........
Figure 9--5: TDS 400A Interconnections, B080000 & up (Cont.) 9--7...
Figure 9--6: TDS 400A Block Diagram, B080000 & up 9--8...........
Figure 9--6: TDS 400A Block Diagram, B080000 & up (Cont.) 9--9....
Figure 10--1: External and front panel modules 10--7.................
Figure 10--2: Internal modules (B010100 - B079999) 10--9.............
Figure 10--3: Internal modules (B080000 - Up) 10--11..................
Figure 10--4: Cables and routing (B010100 - B079999) 10--13...........
Figure 10--5: Cables and routing (B080000 - Up) 10--15................