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Service Manual
TDS 684A, TDS 744A, & TDS 784A
Digitizing Oscilloscope
070-8992-03
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 the Safety Summary prior to
performing service.
Please check for change information
at the rear of this manual.
Fourth Edition: January 1995
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Copyright Tektronix, Inc. 1994, 1995. 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. Printed in the U.S.A. Tektronix, Inc., P.O. Box 1000, Wilsonville, OR 97070–1000 TEKTRONIX and TEK are registered trademarks of Tektronix, Inc.
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WARRANTY Tektronix warrants that this product will be free from defects in materials and workmanship for a period of three (3) years from the date of shipment. If any such 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 th
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Table of Contents General Safety Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix Service Safety Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix Specifications Product Description . . . . . . . . . . . .
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Table of Contents Performance Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4–15 Prerequisites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4–15 Equipment Required . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4–16 TDS 684A Test Record . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4–19 TDS 7XXA Test Reco
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Table of Contents List of Figures 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: Measurement of DC Offset Accuracy at Zero Setting . . . 4–29 Figure 4–5: Initial Test Hookup . . . . . . . . . . . . . . . .
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Table of Contents Figure 4–31: 60 Hz Rejection Test Setup Signal . . . . . . . . . . . . . . . . . . 4–72 Figure 4–32: Subsequent 60 Hz Rejection Test Hookup . . . . . . . . . . . 4–73 Figure 4–33: 60 Hz Rejection Test Result – TDS 684A Shown . . . . . . 4–74 Figure 4–34: Line Count Accuracy Test Hookup . . . . . . . . . . . . . . . . . 4–75 Figure 4–35: Line Count Accuracy Test Setup Waveform – TDS 684A Shown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4–76 Figu
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Table of Contents Figure 6–16: A11 Processor/Display Removal . . . . . . . . . . . . . . . . . . . 6–37 Figure 6–17: Board Bracket Removal . . . . . . . . . . . . . . . . . . . . . . . . . . 6–38 Figure 6–18: A10 Acquisition Board Removal . . . . . . . . . . . . . . . . . . . 6–41 Figure 6–19: Floppy Disk Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6–43 Figure 6–20: Rear Chassis Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . 6–45 Figure 6–21: A16 Low Voltage Po
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Table of Contents vi TDS 684A, TDS 744A, & TDS 784A Service Manual
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Table of Contents List of Tables Table 1–1: Key Features of the TDS 684A and 7XXA Oscilloscopes 1–1 Table 1–2: Record Length vs. Divisions per Record, Samples per Division and Sec/Div Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1–3 Table 1–3: Nominal Traits — Signal Acquisition System . . . . . . . . . . 1–9 Table 1–4: Nominal Traits — Time Base System . . . . . . . . . . . . . . . . 1–10 Table 1–5: Nominal Traits — Triggering System . . . . . . . . . . . . . . . . 1–10 Ta
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Table of Contents Table 6–2: External Inspection Check List . . . . . . . . . . . . . . . . . . . . . 6–5 Table 6–3: Internal Inspection Check List . . . . . . . . . . . . . . . . . . . . . . 6–6 Table 6–4: Tools Required for Module Removal . . . . . . . . . . . . . . . . . 6–11 Table 6–5: Normal Supply Voltages (Measured on J26 and J27 on the A11 DRAM Processor/Display Module) . . . . . . . . . . . . . . . . . . 6–63 Table 6–6: No-Load Supply Voltages (Measured on J5 and J6 on the A17 Main LV
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General Safety Summary Review the following safety precautions to avoid injury and prevent damage to this product or any products connected to it. Only qualified personnel should perform service procedures. Injury Precautions Use Proper Power Cord To avoid fire hazard, use only the power cord specified for this product. Avoid Electric Overload To avoid electric shock or fire hazard, do not apply a voltage to a terminal that is outside the range specified for that terminal. Ground the Product Th
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General Safety Summary Use Proper Voltage Before applying power, ensure that the line selector is in the proper position for the power source being used. Setting Provide Proper Ventilation To prevent product overheating, provide proper ventilation. Do Not Operate With If you suspect there is damage to this product, have it inspected by qualified service personnel. Suspected Failures Do Not Immerse in Liquids Clean the probe using only a damp cloth. Refer to cleaning instructions. Safety Terms an
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General Safety Summary Symbols on the Product The following symbols may appear on the product: Double DANGER Protective Ground ATTENTION Insulated High Voltage (Earth) Terminal Refer to Manual Certifications and Compliances CSA Certified Power CSA Certification includes the products and power cords appropriate for use in the North America power network. All other power cords supplied are approved Cords for the country of use. xi TDS 684A, TDS 744A, & TDS 784A Service Manual
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General Safety Summary xii TDS 684A, TDS 744A, & TDS 784A Service Manual
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Service Safety Summary Only qualified personnel should perform service procedures. Read this Service Safety Summary and the General Safety Summary before performing any service procedures. Do Not Service Alone Do not perform internal service or adjustments of this product unless another person capable of rendering first aid and resuscitation is present. Disconnect Power To avoid electric shock, disconnect the main power by means of the power cord or, if provided, the power switch. Use Caution Wh
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Service Safety Summary xiv TDS 684A, TDS 744A, & TDS 784A Service Manual
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Preface This preface contains information needed to properly use this manual to service the TDS 684A and 7XXA Digitizing Oscilloscopes, as well as general informa- tion critical to safe and effective servicing of this oscilloscope. Manual Structure This manual is divided into sections, such as Specification and Theory of Operation. Further, it is divided into subsections, such as Product Description and Removal and Installation Procedures. Sections containing procedures also contain introduction
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Preface Diagrams contains a block diagram and an interconnection diagram useful for isolating failed modules. Mechanical Parts List includes a table of all replaceable modules, their descriptions, and their Tektronix part numbers. Manual Conventions This manual uses certain conventions which you should become familiar with before doing service. Modules Throughout this manual, any replaceable component, assembly, or part of these Digitizing Oscilloscopes is referred to generically as a module
