Tektronix 684A, 744A User Manual

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

that in all previously published material. Specifications and price change privileges reserved. Printed in the U.S.A. T ektronix, Inc., P.O. Box 1000, Wilsonville, OR 97070–1000 TEKTRONIX and TEK are registered trademarks of T ektronix, Inc.

WARRANTY

T ektronix 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, T ektronix, 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 T ektronix, with shipping charges prepaid. T ektronix shall pay for the return of the product to Customer if the shipment is to a location within the country in which the T ektronix 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. T ektronix shall not be obligated to furnish service under this warranty a) to repair damage resulting from attempts by personnel other than T ektronix representatives to install, repair or service the product; b) to repair damage resulting from improper use or connection to incompatible equipment; or c) 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 WITH RESPECT TO THIS PRODUCT IN LIEU OF ANY OTHER WARRANTIES, EXPRESSED 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 CUST OMER 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.

Specifications

General Safety Summary ix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Service Safety Summary xiii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Preface xv. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Introduction xix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Product Description 1–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

User Interface 1–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Signal Acquisition System 1–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Horizontal System 1–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Trigger System 1–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Acquisition Control 1–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

On-Board User Assistance 1–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Measurement Assistance 1–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Storage 1–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

I/O 1–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Display 1–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Nominal Traits 1–9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Warranted Characteristics 1–15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Typical Characteristics 1–21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Operational Information

Installation 2–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Supplying Operating Power 2–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Operating Environment 2–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Applying and Interrupting Power 2–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Repackaging Instructions 2–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Installed Options 2–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Operating Instructions 2–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Screen Layout 2–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Basic Procedures 2–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Theory of Operation

Logic Conventions 3–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Module Overview 3–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Performance Verification

Performance Verification Procedures 4–1. . . . . . . . . . . . . . . . . . . . . . . . . .

Conventions 4–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Brief Procedures 4–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Self Tests 4–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Functional T ests 4–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TDS 684A, TDS 744A, & TDS 784A Service Manual

Table of Contents

Adjustment Procedures

Maintenance

Performance Tests 4–15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Prerequisites 4–15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Equipment Required 4–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TDS 684A T est Record 4–19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TDS 7XXA T est Record 4–23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Signal Acquisition System Checks 4–27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Time Base System Checks 4–42. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Trigger System Checks 4–44. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Output Signal Checks 4–57. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Option 05 Video Trigger Checks 4–65. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Requirements for Performance 5–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Usage 5–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Equipment Required 5–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Adjustment Instructions 5–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Probe Adjustment for the P6139A Probe 5–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Display Assembly Adjustment 5–21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Options Electrical Parts List Diagrams Mechanical Parts LIst

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 6–15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Procedures for External Modules 6–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Procedures for Outer-Chassis Modules 6–29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Procedures for Inner-Chassis Modules 6–46. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Disassembly for Cleaning 6–53. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Troubleshooting 6–57. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Diagnostics 6–57. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Firmware Updates 6–58. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TDS 684A, TDS 744A, & TDS 784A Service Manual

List of Figures

Table of Contents

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 4–30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4–6: Measurement of DC Accuracy at Maximum Offset

and Position 4–32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4–7: Initial Test Hookup 4–34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4–8: Measurement of Analog Bandwidth 4–36. . . . . . . . . . . . . . . . .

Figure 4–9: Initial Test Hookup 4–38. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4–10: Measurement of Channel Delay – TDS 684A Shown 4–40. .

Figure 4–11: Initial Test Hookup 4–42. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4–12: Measurement of Accuracy

— Long-Term and Delay Time 4–44. . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4–13: Initial Test Hookup 4–45. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4–14: Measurement of Time Accuracy for Pulse and

Glitch Triggering 4–47. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4–15: Initial Test Hookup 4–48. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4–16: Measurement of Trigger-Level Accuracy 4–50. . . . . . . . . . . .

Figure 4–17: Initial Test Hookup 4–53. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4–18: Measurement of Trigger Sensitivity

— 50 MHz Results Shown on a TDS 684A Screen 4–54. . . . . . . . . . . .

Figure 4–19: Initial Test Hookup 4–57. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4–20: Measurement of Main Trigger Out Limits 4–59. . . . . . . . . . .

Figure 4–21: Initial Test Hookup 4–61. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4–22: Measurement of Probe Compensator Frequency 4–62. . . . .

Figure 4–23: Subsequent Test Hookup 4–63. . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4–24: Measurement of Probe Compensator Amplitude 4–64. . . . .

Figure 4–25: Jitter Test Hookup 4–66. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4–26: Jitter Test Displayed Waveform – TDS 684A Shown 4–67. .

Figure 4–27: Jitter Test When Completed – TDS 684A Shown 4–68. . . . .

Figure 4–28: Triggered Signal Range Test – 300 mV 4–70. . . . . . . . . . . . . .

Figure 4–29: Triggered Signal Range Test – 75 mV 4–71. . . . . . . . . . . . . . .

Figure 4–30: 60 Hz Rejection Test Hookup 4–72. . . . . . . . . . . . . . . . . . . . . .

TDS 684A, TDS 744A, & TDS 784A Service Manual

iii

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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4–36: Line Count Accuracy Correct Result Waveform 4–77. . . . . .

Figure 4–37: PG502 Setup for Sync Duty Cycle Test 4–79. . . . . . . . . . . . . .

Figure 4–38: Sync Duty Cycle Test: One-Div Neg Pulse Waveform 4–80. .

Figure 4–39: Sync Duty Cycle Test: Critically Adjusted Pulse 4–81. . . . . .

Figure 5–1: Accessing the Protection Switch 5–9. . . . . . . . . . . . . . . . . . . .

Figure 5–2: Hookup for Probe Compensation 5–11. . . . . . . . . . . . . . . . . . .

Figure 5–3: Performing Probe Compensation 5–12. . . . . . . . . . . . . . . . . . .

Figure 5–4: Proper and Improper Probe Compensation 5–12. . . . . . . . . . .

Figure 5–5: Exposing the Inner Probe Tip 5–13. . . . . . . . . . . . . . . . . . . . . .

Figure 5–6: Initial Test Hookup 5–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 5–7: Exposing the Probe Body 5–16. . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 5–8: Initial Test Hookup 5–17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 5–9: Locations of P6139A Probe Adjustments 5–19. . . . . . . . . . . . .

Figure 5–10: Adjustments versus Front-Corner Response 5–20. . . . . . . . .

Figure 5–11: Five and Ten Percent Luminance Patches 5–22. . . . . . . . . . .

Figure 6–1: External Modules 6–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 6–2: Outer-Chassis Modules 6–13. . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 6–3: Inner-Chassis Modules 6–14. . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 6–4: Knob Removal 6–17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 6–5: Line Fuse and Line Cord Removal 6–18. . . . . . . . . . . . . . . . . .

Figure 6–6: Rear Cover and Cabinet Removal 6–21. . . . . . . . . . . . . . . . . .

Figure 6–7: Front Cover, Trim Ring, Menu Buttons, and

Attenuator Panel Removal (Front Cover not Shown) 6–22. . . . . . . . .

Figure 6–8: A12 Front-Panel Assembly Removal 6–24. . . . . . . . . . . . . . . . .

Figure 6–9: Disassembly of Front-Panel Assembly 6–25. . . . . . . . . . . . . . .

Figure 6–10: Cabinet Modules Removal 6–28. . . . . . . . . . . . . . . . . . . . . . . .

Figure 6–11: A14 D1 Bus and Analog-Power and Digital-Power

Cables Removal 6–30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 6–12: Remove Circuit Board Assembly From Oscilloscope 6–31. .

Figure 6–13: Remove Circuit Board From Assembly 6–32. . . . . . . . . . . . .

Figure 6–14: Circuit Board Installed 6–34. . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 6–15: Circuit Board Removal 6–35. . . . . . . . . . . . . . . . . . . . . . . . . .

TDS 684A, TDS 744A, & TDS 784A Service Manual

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 Power Supply Removal 6–47. . . . . . . . . . .

Figure 6–22: Display Assembly Removal 6–49. . . . . . . . . . . . . . . . . . . . . . .

Figure 6–23: Display Driver Board Removal 6–50. . . . . . . . . . . . . . . . . . . .

Figure 6–24: Front Subpanel Removal 6–52. . . . . . . . . . . . . . . . . . . . . . . . .

Figure 6–25: Accessing the Protection Switch 6–58. . . . . . . . . . . . . . . . . . .

Figure 6–26: Primary Troubleshooting Procedure 6–59. . . . . . . . . . . . . . .

Figure 6–27: Module Isolation Troubleshooting Procedure 6–61. . . . . . . .

Figure 6–28: A16 Low Voltage Power Supply Module Isolation

Troubleshooting Procedure 6–62. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 6–29: Power Supply Voltage Measurement Locations 6–63. . . . . . .

Figure 6–30: Color Display Troubleshooting Procedure 6–64. . . . . . . . . . .

Figure 6–31: Horizontal and Vertical Sync Signals – Color Display 6–65. Figure 6–32: A Video Signal with White, Black, and

Blanking Levels – Color Display 6–65. . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 6–33: Processor/Acquisition Troubleshooting Procedure 6–66. . . .

Figure 6–34: Processor/Front Panel Troubleshooting Procedure 6–67. . . .

Figure 6–35: Attenuator/Acquisition Troubleshooting Procedure 6–68. . . Figure 6–36: A11 DRAM Processor/Display Module

(View of Right Side) 6–70. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 6–37: A11 DRAM Processor/Display Module

(View of Upper Left Corner) 6–71. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 6–38: A11 DRAM Processor/Display Module

(View of Lower Left Corner) 6–71. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 6–39: A10 Acquisition Module (View of Lower Right Corner) 6–72

Figure 9–1: Interconnections 9–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 9–2: Block Diagram 9–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 10–1: External Modules 10–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 10–2: Outer-Chassis Modules 10–9. . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 10–3: Inner-Chassis Modules 10–10. . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 10–4: Cables, Bottom View 10–11. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 10–5: Cables, Top View 10–13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 10–6: Floppy Disk 10–15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 10–7: Accessories 10–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TDS 684A, TDS 744A, & TDS 784A Service Manual

Table of Contents

TDS 684A, TDS 744A, & TDS 784A Service Manual

List of Tables

Table of Contents

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. . . . . . . . . . . . . . . .

Table 1–6: Nominal Traits — Display System 1–11. . . . . . . . . . . . . . . . . . .

Table 1–7: Nominal Traits — GPIB Interface, Output Ports, and

Power Fuse 1–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 1–8: Nominal Traits — Data Handling and Reliability 1–12. . . . . .

Table 1–9: Nominal Traits — Mechanical 1–13. . . . . . . . . . . . . . . . . . . . . .

Table 1–10: Warranted Characteristics

— Signal Acquisition System 1–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 1–11: Warranted Characteristics — Time Base System 1–17. . . . . .

Table 1–12: Warranted Characteristics — Triggering System 1–18. . . . .

Table 1–13: Warranted Characteristics — Output Ports, Probe

Compensator, and Power Requirements 1–18. . . . . . . . . . . . . . . . . . . .

Table 1–14: Warranted Characteristics — Environmental 1–19. . . . . . . .

Table 1–15: Typical Characteristics — Signal Acquisition System 1–21. .

Table 1–16: Typical Characteristics — Triggering System 1–23. . . . . . . .

Table 2–1: Power-Cord Conductor Identification 2–2. . . . . . . . . . . . . . . .

Table 2–2: Power Cord Identification 2–2. . . . . . . . . . . . . . . . . . . . . . . . .

Table 2–3: Effects of Corrupted Data 2–4. . . . . . . . . . . . . . . . . . . . . . . . . .

Table 4–1: Test Equipment 4–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 4–2: DC Offset Accuracy (Zero Setting) 4–28. . . . . . . . . . . . . . . . . .

Table 4–3: DC Accuracy 4–31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 4–4: Analog Bandwidth 4–35. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 5–1: Calibration Tests 5–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 5–2: Adjustments Required for Module Replaced 5–4. . . . . . . . . .

Table 5–3: Adjustments and Dependencies 5–4. . . . . . . . . . . . . . . . . . . . .

Table 5–4: Test Equipment, Fixtures, and Supplies 5–5. . . . . . . . . . . . . .

Table 5–5: GPIB Board Configuration 5–7. . . . . . . . . . . . . . . . . . . . . . . . .

Table 6–1: Relative Susceptibility to Static-Discharge Damage 6–3. . . . .

TDS 684A, TDS 744A, & TDS 784A Service Manual

vii

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 Power Supply Module) 6–63. . . . . . . . . . . . . . . . . . . .

Table 7–1: Options 7–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 7–2: Standard Accessories 7–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 7–3: Optional Accessories 7–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 7–4: Accessory Software 7–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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TDS 684A, TDS 744A, & TDS 784A Service Manual

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

Avoid Electric Overload

Ground the Product

Do Not Operate Without

Covers

Use Proper Fuse

Do Not Operate in

Wet/Damp Conditions

Do Not Operate in

Explosive Atmosphere

To avoid fire hazard, use only the power cord specified for this product.

To avoid electric shock or fire hazard, do not apply a voltage to a terminal that is outside the range specified for that terminal.

This product is grounded through the grounding conductor of the power cord. To avoid electric shock, the grounding conductor must be connected to earth ground. Before making connections to the input or output terminals of the product, ensure that the product is properly grounded.

To avoid electric shock or fire hazard, do not operate this product with covers or panels removed.

To avoid fire hazard, use only the fuse type and rating specified for this product.

To avoid electric shock, do not operate this product in wet or damp conditions.

To avoid injury or fire hazard, do not operate this product in an explosive atmosphere.

Keep Probe Surface Clean

To avoid electric shock and erroneous readings, keep probe surface clean.

Product Damage Precautions

Use Proper Power Source

TDS 684A, TDS 744A, & TDS 784A Service Manual

Do not operate this product from a power source that applies more than the voltage specified.

General Safety Summary

Use Proper Voltage

Setting

Provide Proper Ventilation

Do Not Operate With

Suspected Failures

Do Not Immerse in Liquids

Before applying power, ensure that the line selector is in the proper position for the power source being used.

To prevent product overheating, provide proper ventilation.

If you suspect there is damage to this product, have it inspected by qualified service personnel.

Clean the probe using only a damp cloth. Refer to cleaning instructions.

Safety Terms and Symbols

Terms in This Manual

These terms may appear in this manual:

WARNING. Warning statements identify conditions or practices that could result in injury or loss of life.

Terms on the Product

CAUTION. Caution statements identify conditions or practices that could result in damage to this product or other property.

These terms may appear on the product: DANGER indicates an injury hazard immediately accessible as you read the

marking. WARNING indicates an injury hazard not immediately accessible as you read the

marking. CAUTION indicates a hazard to property including the product.

TDS 684A, TDS 744A, & TDS 784A Service Manual

General Safety Summary

Symbols on the Product

The following symbols may appear on the product:

DANGER

High Voltage

Certifications and Compliances

CSA Certified Power

Cords

CSA Certification includes the products and power cords appropriate for use in the North America power network. All other power cords supplied are approved for the country of use.

Protective Ground

(Earth) T erminal

ATTENTION

Refer to

Manual

Double

Insulated

TDS 684A, TDS 744A, & TDS 784A Service Manual

General Safety Summary

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TDS 684A, TDS 744A, & TDS 784A Service Manual

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

Disconnect Power

Use Caution When

Servicing the CRT

Use Care When Servicing

With Power On

Do not perform internal service or adjustments of this product unless another person capable of rendering first aid and resuscitation is present.

To avoid electric shock, disconnect the main power by means of the power cord or, if provided, the power switch.

To avoid electric shock or injury, use extreme caution when handling the CRT. Only qualified personnel familiar with CRT servicing procedures and precautions should remove or install the CRT.

CRTs retain hazardous voltages for long periods of time after power is turned off. Before attempting any servicing, discharge the CRT by shorting the anode to chassis ground. When discharging the CRT, connect the discharge path to ground and then the anode. Rough handling may cause the CRT to implode. Do not nick or scratch the glass or subject it to undue pressure when removing or installing it. When handling the CRT, wear safety goggles and heavy gloves for protection.

Dangerous voltages or currents may exist in this product. Disconnect power, remove battery (if applicable), and disconnect test leads before removing protective panels, soldering, or replacing components.

To avoid electric shock, do not touch exposed connections.

X-Radiation

TDS 684A, TDS 744A, & TDS 784A Service Manual

To avoid x-radiation exposure, do not modify or otherwise alter the high-voltage circuitry or the CRT enclosure. X-ray emissions generated within this product have been sufficiently shielded.

xiii

Service Safety Summary

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TDS 684A, TDS 744A, & TDS 784A Service Manual

Preface

Manual Structure

This preface contains information needed to properly use this manual to service the TDS 684A and 7XXA Digitizing Oscilloscopes, as well as general information critical to safe and effective servicing of this oscilloscope.

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 introductions to those procedures. Be sure to read these introductions because they provide information needed to do the service correctly and efficiently. The following is a brief description of each manual section.

H Specification contains a product description of the TDS 684A and

7XXA Digitizing Oscilloscopes and tables of the characteristics and

descriptions that apply to it. H Operating Information includes general information and operating instruc-

tions at the level needed to safely power on and service this oscilloscope. A

statement of the service strategy that this manual supports, and instructions

for shipment of the Digitizing Oscilloscopes are found in this section. H Theory of Operation contains circuit descriptions that support general service

and fault isolation down to the module level. H Performance Verification contains a collection of procedures for confirming

that these Digitizing Oscilloscopes function properly and meet warranted

limits. H Adjustment Procedures contains a collection of procedures for adjusting

these Digitizing Oscilloscopes to meet warranted limits. H Maintenance contains information and procedures for doing preventive and

corrective maintenance of these Digitizing Oscilloscopes. Instructions for

cleaning, for module removal and installation, and for fault isolation to a

module are found here. H Options contains information on servicing any of the factory-installed

options that may be present in your oscilloscope.

H Electrical Parts List contains a statement referring you to Mechanical

Replaceable Parts, where both electrical and mechanical modules are listed.

TDS 684A, TDS 744A, & TDS 784A Service Manual

Preface

Manual Conventions

H Diagrams contains a block diagram and an interconnection diagram useful

for isolating failed modules.

H Mechanical Parts List includes a table of all replaceable modules, their

descriptions, and their Tektronix part numbers.

This manual uses certain conventions which you should become familiar with before doing service.

Modules

Safety

Symbols

Throughout this manual, any replaceable component, assembly, or part of these Digitizing Oscilloscopes is referred to generically as a module. In general, a module is an assembly, like a circuit board, rather than a component, like a resistor or an integrated circuit. Sometimes a single component is a module; for example, each chassis part of the oscilloscope is a module.

Symbols and terms related to safety appear in the Safety Summary found at the beginning of this manual.

Besides the symbols related to safety, this manual uses the following symbols:

STOP. The stop labels information which must be read in order to correctly do service and to avoid incorrectly using or applying service procedures.

The clock icon labels procedure steps which require a pause to wait for the oscilloscope to complete some operation before you can continue.

Various icons such as the example icon at the left are used in procedures to help identify certain readouts and menu functions on screen.

Related Manuals

xvi

The TDS 684A and 7XXA Digitizing Oscilloscopes come with the following manuals:

TDS 684A, TDS 744A, & 784A User Manual (Tektronix part number 070-8991-XX) contains a tutorial to quickly show you how to operate the TDS 684A and 7XXA Digitizing Oscilloscopes and an in depth discussion of how to more completely use their features. Applications are also discussed.

TDS 684A, TDS 744A, & TDS 784A Reference (Tektronix part number 070-8999-XX) contains a brief overview of oscilloscope operation.

TDS 684A, TDS 744A, & TDS 784A Service Manual

Preface

TDS Family (400, 5XXA, 6XXA, and 7XXA) Programmer Manual (Tektronix part number 070-8709-XX) contains information for programmed operation via the GPIB interface. Included is the complete command set, setup information, and programming examples.

TDS 684A, TDS 744A, & 784A Technical Reference (Tektronix part number 070-8990-XX) contains performance verification procedures and specifications.

TDS 684A, TDS 744A, & TDS 784A Service Manual

xvii

Preface

xviii

TDS 684A, TDS 744A, & TDS 784A Service Manual

Introduction

Service Strategy

STOP. Throughout this manual, any field-replaceable component, assembly, or part of this oscilloscope is referred to generically as a module.

This manual contains all the information needed for periodic maintenance of the TDS 684A and 7XXA Digitizing Oscilloscopes. (Examples of such information are procedures for checking performance and for readjustment.) Further, it contains all information for corrective maintenance down to the module level. This means that the procedures, diagrams, and other troubleshooting aids help isolate failures to a specific module, rather than to components of that module. Once a failure is isolated, replace the module with a fresh unit obtained from the factory.

All modules are listed in Mechanical Parts List. To isolate a failure to a module, use the fault isolation procedures found in Section 6, Maintenance Information. To remove and replace any failed module, follow the instructions in Removal and Installation Procedures, also found in Section 6.

Service Offerings

Warranty Repair Service

Repair or Calibration

Service

Tektronix provides service to cover repair under warranty as well as other services that may provide a cost-effective answer to your service needs.

Whether providing warranty repair service or any of the other services listed below, Tektronix service technicians, trained on Tektronix products, are best equipped to service your TDS 684A and 7XXA Digitizing Oscilloscopes. Tektronix technicians are appraised of the latest information on improvements to the product as well as the latest new options to the product.

Tektronix warrants this product for three years from date of purchase, excluding probes for which the warranty is one year. (The warranty appears after the title page and copyright page in this manual.) Tektronix technicians provide warranty service at most Tektronix service locations worldwide. Your Tektronix product catalog lists all service locations worldwide.

The following services may be purchased to tailor repair and/or calibration of your TDS 684A and 7XXA Digitizing Oscilloscopes to fit your requirements.

TDS 684A, TDS 744A, & TDS 784A Service Manual

xix

Introduction

Option 9C. When you order the TDS 684A and 7XXA Digitizing Oscilloscopes with option 9C, each one is shipped with a Certificate of Calibration and Test Data Report. This certificate provides traceability to the National Institute of Standards and Technology (NIST). It certifies procedures used to calibrate the oscilloscope comply with U. S. Military Standard 45662A.

At-Depot Service. Tektronix offers several standard-priced adjustment (calibration) and repair services:

H A single repair and/or adjustment. H Calibrations using equipment and procedures that meet the traceability

standards specific to the local area.

H Annual maintenance agreements that provide for either calibration and repair

or calibration only of the oscilloscope.

Of these services, the annual maintenance agreement offers a particularly cost-effective approach to service for many owners of the TDS 684A and 7XXA Digitizing Oscilloscopes. Such agreements can be purchased to span several years.

Self Service

On-Site Service. The annual maintenance agreement can be purchased with

on-site service, with repair and calibration done at your facility. This service reduces the time your oscilloscope is out of service when calibration or repair is required.

Tektronix supports repair to the module level by providing Module Exchange and Module Repair and Return.

Module Exchange. This service reduces down time for repair by allowing you to exchange most modules for remanufactured ones. Tektronix ships you an updated and tested exchange module from the Beaverton, Oregon service center, typically within 24 hours. Each module comes with a 90-day service warranty.

Module Repair and Return. This service returns to you within 10 days the same module that you shipped to Tektronix. The module shipped is repaired, tested, and returned to you from the Beaverton, Oregon service center. It is not updated to match current modules of the same type. Again, each module comes with a 90-day service warranty.

For More Information. Contact your local Tektronix service center or sales engineer for more information on any of the repair or adjustment services just described.

TDS 684A, TDS 744A, & TDS 784A Service Manual

Before You Begin

Introduction

This manual is for servicing the TDS 684A and 7XXA Digitizing Oscilloscopes. To prevent injury to yourself or damage to the oscilloscope, do the following tasks before you attempt service:

H Be sure you are a qualified service person. H Read the Safety Summary found at the beginning of this manual. H Read Service Strategy in this section and Supplying Operating Power in

section 2. When using this manual for servicing, be sure to heed all warnings, cautions, and

notes.

TDS 684A, TDS 744A, & TDS 784A Service Manual

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Introduction

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TDS 684A, TDS 744A, & TDS 784A Service Manual

Specifications

Product Description

This section begins with a general description of the traits of the TDS 684A and 7XXA Digitizing Oscilloscopes. Three sections follow, one for each of three classes of traits: nominal traits, warranted characteristics, and typical character- istics.

The TDS 684A and 7XXA Digitizing Oscilloscopes are portable, four-channel instruments suitable for use in a variety of test and measurement applications and systems. Table 1–1 lists key features.

T able 1–1: Key Features of the TDS 684A and 7XXA Oscilloscopes

Feature TDS 684A TDS 7XXA

Digitizing rate, maximum 5 GS/s on each channel

simultaneously

Analog bandwidth 1 GHz TDS 744A: 500 MHz

TDS 744A: 2 GS/s TDS 784A: 4 GS/s

TDS 784A: 1 GHz Channels Four, each with 8-bit resolution Record lengths, maximum 15,000 samples 50,000 samples

(500,000 with option 1M) Acquisition modes Sample, envelope, and

average

Trigger modes Include: edge, logic, and pulse.

Video trigger , with option 05, modes include: NTSC, SECAM, PAL, HDTV, and FlexFormat.

Display Color for distinguishing among waveforms, measurements, and

associated text

Storage 1.44 Mbyte, 3.5 inch, DOS 3.3-or-later floppy disk.

NVRAM storage for saving waveforms, hardcopies, and setups

I/O Full GPIB programmability.

Hardcopy output using GPIB, RS-232, or Centronics ports

Sample, envelope, average,

high-resolution, and

peak-detect

TDS 684A, TDS 744A, & TDS 784A Service Manual

1–1

Specifications

User Interface

Use a combination of front-panel buttons, knobs, and on-screen menus to control the many functions of the oscilloscope. The front-panel controls are grouped according to function: vertical, horizontal, trigger, and special. Set a function you adjust often, such as vertical positioning or the time base setting, directly by its own front-panel knob. Set a function you change less often, such as vertical coupling or horizontal mode, indirectly using a selected menu.

Menus

Indicators

General Purpose Knob

GUI

Pressing one (sometimes two) front-panel button(s), such as vertical menu, displays a main menu of related functions, such as coupling and bandwidth, at the bottom of the screen. Pressing a main-menu button, such as coupling, displays a side menu of settings for that function, such as AC, DC, or GND (ground) coupling, at the right side of the screen. Pressing a side-menu button selects a setting such as DC.

On-screen readouts help you keep track of the settings for various functions, such as vertical and horizontal scale and trigger level. Some readouts use the cursors or the automatic parameter extraction feature (called measure) to display the results of measurements made or the status of the instrument.

Assign the general purpose knob to adjust a selected parameter function. More quickly change parameters by toggling the SHIFT button. Use the same method as for selecting a function, except the final side-menu selection assigns the general purpose knob to adjust some function, such as the position of measurement cursors on screen, or the setting for a channel fine gain.

The user interface also makes use of a GUI, or Graphical User Interface, to make setting functions and interpreting the display more intuitive. Some menus and status are displayed using iconic representations of function settings, such as those shown here for full, 250 MHz and 20 MHz bandwidth. Such icons allow you to more readily determine status or the available settings.

Signal Acquisition System

The signal acquisition system provides four, full-featured vertical channels with calibrated vertical scale factors from 1 mV to 10 V per division. All channels can be acquired simultaneously.

Each of the full-featured channels can be displayed, vertically positioned, and offset, can have their bandwidth limited (250 MHz or 20 MHz) and their vertical coupling specified. Fine gain can also be adjusted.

1–2

TDS 684A, TDS 744A, & TDS 784A Service Manual

Horizontal System

Record Length

Specifications

Besides these channels, up to three math waveforms and four reference waveforms are available for display. (A math waveform results when you specify dual waveform operations, such as add, on any two channels. A reference waveform results when you save a waveform in a reference memory.)

There are three horizontal display modes: main only, main intensified, and delayed only. You can select among various horizontal record length settings.

A feature called “Fit to Screen” allows you to view entire waveform records within the 10 division screen area. In other words, waveforms are compressed to fit on the screen. See Table 1–2.

T able 1–2: Record Length vs. Divisions per Record, Samples per Division and Sec/Div Sequence

Divisions per Record Sample/Division (Sec/Div Sequence)

Fit to Screen ON Fit to Screen OFF 50 (1–2–5)

500 10 divs 10 divs 1000 20 divs 10 divs 2500 50 divs 10 divs 5000 100 divs 10 divs 15000 300 divs 15 divs 50000 (TDS 7XXA only) 1,000 divs 10 divs 75000 (TDS 7XXA opt. 1M only) 1,500 divs 15 divs 100000 (TDS 7XXA opt. 1M only) 2,000 divs 10 divs 130000 (TDS 7XXA opt. 1M only) 2,600 divs 13 divs 250000 (TDS 7XXA opt. 1M only,

1 or 2 channels) 500000 (TDS 7XXA opt. 1M only,

1 channel)

5,000 divs 10 divs

10,000 divs 10 divs

(Sample/Div & Sec/Div

Sequence varies)

Both the delayed only display and the intensified zone on the main intensified display may be delayed by time with respect to the main trigger. Both can be set to display immediately after the delay (delayed runs after main mode). The delayed display can also be set to display at the first valid trigger after the delay (delayed-triggerable modes).

TDS 684A, TDS 744A, & TDS 784A Service Manual

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+ 264 hidden pages