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

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

viii

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

xii

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

1–3

Specifications

Trigger System

The delayed display (or the intensified zone) may also be delayed by a selected number of events. In this case, the events source is the delayed-trigger source. The delayed trigger can also be set to occur after a number of events plus an amount of time.

The triggering system supports a varied set of features for triggering the signal-acquisition system. Trigger signals recognized include:

H Edge (main- and delayed-trigger systems): This familiar type of triggering is

fully configurable for source, slope, coupling, mode (auto or normal), and holdoff.

H Logic (main-trigger system): This type of triggering can be based on pattern

(asynchronous) or state (synchronous). In either case, logic triggering is configurable for sources, for boolean operators to apply to those sources, for logic pattern or state on which to trigger, for mode (auto or normal), and for holdoff. Time qualification may be selected in pattern mode. Another class of logic trigger, setup/hold, triggers when data in one trigger source changes state within the setup and hold times that you specify relative to a clock in another trigger source.

Acquisition Control

H Pulse (main-trigger system): Pulse triggering is configurable for triggering

on runt or glitch pulses, or on pulse widths or periods inside or outside limits that you specify. It can also trigger on a pulse edge that has a slew rate faster or slower than the rate you specify. The pulse trigger is also configurable for source, polarity, mode, and holdoff.

H Video (with option 05: Video Trigger): Video triggering is compatible with

standard NTSC, PAL, SECAM, and HDTV formats. An additional feature called FlexFormat format on which to trigger.

You can choose where the trigger point is located within the acquired waveform record by selecting the amount of pretrigger data displayed. Presets of 10%, 50%, and 90% of pretrigger data can be selected in the horizontal menu, or the general purpose knob can be assigned to set pretrigger data to any value within the 0% to 100% limits.

You can specify a mode and manner to acquire and process signals that matches your measurement requirements.

(flexible format) allows the user to define the video

1–4

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

H Select the mode for interpolation (linear or sin (x)/x). This can increase the

H Use sample, envelope, and average modes to acquire signals.

H Set the acquisition to stop after a single acquisition (or sequence of

H Select channel sources for compliance with limit tests. You can direct the

On-Board User Assistance

Help and autoset can assist you in setting up the Digitizing Oscilloscope to make your measurements.

Specifications

apparent sample rate on the waveform when the maximum real-time rate is exceeded.

With the TDS 7XXA, also use high-resolution and peak-detect modes.

acquisitions if acquiring in average or envelope modes) or after a limit condition has been met.

TDS to signal you or generate hard copy output either to a printer or to a floppy-disk file based on the results. Also, you can create templates for use in limit tests.

Help

Autoset

Help displays operational information about any front-panel control. When help mode is in effect, manipulating any front-panel control causes the Digitizing Oscilloscope to display information about that control. When help is first invoked, an introduction to help is displayed on screen.

Autoset automatically sets up the Digitizing Oscilloscope for a viewable display based on the input signal.

Measurement Assistance

Once you have set up to make your measurements, the cursor and measure features can help you quickly make those measurements.

Cursor

Three types of cursors are provided for making parametric measurements on the displayed waveforms. Horizontal bar cursors (H Bar) measure vertical parameters (typically volts). Vertical bar cursors (V Bar) measure horizontal parameters (typically time or frequency). Paired cursors measure both amplitude and time simultaneously. These are delta measurements; that is, measurements based on the difference between two cursors.

Both H Bar and V Bar cursors can also be used to make absolute measurements. For the H Bars, either cursor can be selected to read out its voltage with respect to any channel’s ground reference level. For the V Bars, the cursors measure time

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

1–5

Specifications

with respect to the trigger point (event) of the acquisition. The cursors can also control the portion of the waveform on which automatic measurements are made.

For time measurements, units can be either seconds or hertz (for 1/time). With the video trigger option installed (Option 05), you can measure the video

line number using the vertical cursors. You can measure IRE amplitude (NTSC) using the horizontal cursors with or without the video trigger option installed.

Measure

Digital Signal Processing

(DSP)

Storage

Measure can automatically extract parameters from the signal input to the Digitizing Oscilloscope. Any four out of the 25 parameters available can be displayed to the screen. The waveform parameters are measured continuously with the results updated on-screen as the Digitizing Oscilloscope continues to acquire waveforms.

An important component of the multiprocessor architecture of this Digitizing Oscilloscope is Tektronix’s proprietary digital signal processor, the DSP. This dedicated processor supports advanced analysis of your waveforms when doing such compute-intensive tasks as interpolation, waveform math, and signal averaging. It also teams with a custom display system to deliver specialized display modes (See Display, later in this description.)

Acquired waveforms may be saved in any of four nonvolatile REF (reference) memories or on a 3.5 inch, DOS 3.3-or-later compatible disk. Any or all of the saved waveforms may be displayed for comparison with the waveforms being currently acquired.

The source and destination of waveforms to be saved may be chosen. You can save any of the four channels to any REF memory or move a stored reference from one REF memory to another. Reference waveforms may also be written into a REF memory location via the GPIB interface.

I/O

1–6

The oscilloscope is fully controllable and capable of sending and receiving waveforms over the GPIB interface (IEEE Std 488.1–1987/IEEE Std 488.2–1987 standard). This feature makes the instrument ideal for making automated measurements in a production or research and development environment that calls for repetitive data taking. Self-compensation and self-diagnostic features built into the Digitizing Oscilloscope to aid in fault detection and servicing are also accessible using commands sent from a GPIB controller.

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

Display

Specifications

The oscilloscope can also output copies of its display using the hardcopy feature. This feature allows you to output waveforms and other on-screen information to a variety of graphic printers and plotters from the TDS front panel, providing hard copies without requiring you to put the TDS into a system-controller environment. You can make hardcopies in a variety of popular output formats, such as PCX, TIFF, BMP, RLE, EPS, Interleaf, and EPS mono or color. You can also save hardcopies in a disk file in any of the formats above. The hardcopies obtained are based on what is displayed on-screen at the time hardcopy is invoked. The hardcopies can be stamped with date and time and spooled to a queue for printing at a later time. You can output screen information via GPIB, RS-232C, or Centronics interfaces.

The TDS 684A and 7XXA Digitizing Oscilloscopes offer flexible display options. You can customize the following attributes of your display:

H Color: Waveforms, readouts, graticule, and variable persistence with color

coding

Zoom

H Intensity: waveforms, readouts, and graticule H Style of waveform display(s): vectors or dots, intensified or nonintensified

samples, infinite persistence, and variable persistence with color coding

H Interpolation method: Sin(x)/x or Linear H Display format: xy or yt with various graticule selections including NTSC

and PAL to be used with video trigger (option 05)

This oscilloscope also provides an easy way to focus in on those waveform features you want to examine up close. By invoking zoom, you can magnify the waveform using the vertical and horizontal controls to expand (or contract) and position it for viewing.

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

1–7

Specifications

1–8

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

Nominal Traits

Ranges, Offset

This section contains a collection of tables that list the various nominal traits that describe the TDS 684A and 7XXA oscilloscopes. Electrical and mechanical traits are included.

Nominal traits are described using simple statements of fact such as “Four, all identical” for the trait “Input Channels, Number of,” rather than in terms of limits that are performance requirements.

T able 1–3: Nominal Traits — Signal Acquisition System

Name Description

Bandwidth Selections 20 MHz, 250 MHz, and FULL Samplers, Number of Four, simultaneous Digitized Bits, Number of 8 bits Input Channels, Number of Four Input Coupling DC, AC, or GND Input Impedance Selections

1 M or 50 

Volts/Div Setting Offset Range

1 mV/div – 100 mV/div

±1 V

101 mV/div – 1 V/div

1.01 V/div – 10 V/div Range, Position ±5 divisions Range, 1 M Sensitivity 1 mV/div to 10 V/div Range, 50  Sensitivity 1 mV/div to 1 V/div

Displayed vertically with 25 digitization levels (DLs) per division and 10.24 divisions dynamic range with zoom off. A DL is the smallest voltage level change of the oscilloscope input that can be resolved by the 8-bit A-D Converter. Expressed as a voltage, a DL is equal to 1/25 of a division times the volts/division setting.

The sensitivity ranges from 1 mV/div to 10 V/div (for 1 M) or to 1 V/div (for 50 ) in a 1–2–5 sequence of coarse settings with Fit-to-Screen off. Between coarse settings, the sensitivity can be finely adjusted with a resolution equal to 1% of the more sensitive coarse setting. For example, between 50 mV/div and 100 mV/div , the volts/division can be set with 0.5 mV resolution.

±10 V ±100 V

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

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Nominal Traits

T able 1–4: Nominal Traits — Time Base System

Name Description

Range, Sample-Rate

Range, Interpolated Waveform Rate

Range, Seconds/Division TDS 684A: 0.2 ns/div to 10 s/div

Record Length Selection 500 samples, 1000 samples, 2500 samples 5000 samples, 15000 samples

1,3

2,3

TDS 684A; 5 Samples/sec to 5 GSamples/sec on four channels simultaneously TDS 744A: 5 Samples/sec to 2 GSamples/sec when acquiring 1 channel

to 1 G Sample/sec when acquiring 2 channels, or to 500 MSamples/sec when acquiring 3 or 4 channels

TDS 784A: 5 Samples/sec to 4 GSamples/sec when acquiring 1 channel to 2 G Sample/sec when acquiring 2 channels, or to 1 GSamples/sec when acquiring 3 or 4 channels

TDS 684A: 10 GSamples/sec to 250 GSamples/sec TDS 744A: 1 GSamples/sec to 100 GSamples/sec TDS 784A: 2 GSamples/sec to 250 GSamples/sec

TDS 744A: 0.5 ns/div to 10 s/div TDS 784A: 0.2 ns/div to 10 s/div

The TDS 7XXA also offers: 50000 samples and, with its option 1M, 75000, 100000, 130000, 250000 (1 or 2 channels), or 500000 (1 channel) samples

The range of real-time rates, expressed in samples/second, at which a digitizer samples signals at its inputs and stores the samples in memory to produce a record of time-sequential samples.

The range of waveform rates for interpolated (or equivalent-time on the TDS 7XXA) waveform records.

The Waveform Rate (WR) is the equivalent sample rate of a waveform record. For a waveform record acquired by real-time sampling of a single acquisition, the waveform rate is the same as the real-time sample rate; for a waveform created by interpolation of real-time samples from a single acquisition or, on applicable products, the equivalent-time sampling of multiple acquisitions, the waveform rate created is faster than the real time sample rate. For all these cases, the waveform rate is 1/(Waveform Interval) for the waveform record, where the waveform interval (WI) is the time between the samples in the waveform record.

T able 1–5: Nominal Traits — Triggering System

Name Description

Range, Delayed Trigger Time Delay 16 ns to 250 s Range, Events Delay TDS 684A; 2 to 10,000,000

TDS 7XXA: 1 to 10,000,000

Range (Time) for Pulse-Glitch, Pulse-Width, Time-Qualified Runt Triggering, or Slew Rate Trigger, Delta Time

1 ns to 1 s

1–10

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

T able 1–5: Nominal Traits — Triggering System (Cont.)

Ranges, Setup and Hold for

TimeSetup/Hold Violation T rigger

Ranges, Trigger Level or Threshold

Name Description

Feature Min to max

Setup Time

Nominal Traits

–100 ns to 100 ns

Video Trigger Modes of Operation (Option 05 Video Trigger)

Hold Time Setup + Hold Time

For Setup Time, positive numbers mean a data transition before the clock edge and negative means a transition after the clock edge.

For Hold Time, positive numbers mean a data transition after the clock edge and negative means a transition before the clock edge.

Setup + Hold Time is the algebraic sum of the Setup Time and the Hold Time programmed by the user.

Source Range

Any Channel Auxiliary Line

Supports the following video standards:

H NTSC (525/60) – 2 field mono or 4 field H PAL (625/50) – 2 field mono or SECAM, 8 field H HDTV –

(787.5/60) (1050/60) (1125/60) (1250/60)

H FlexFormat

(user definable standards)

–1 ns to 100 ns 2 ns

±12 divisions from center of screen ±8 V ±400 V

T able 1–6: Nominal Traits — Display System

Name Description

Video Display Color display, 7 inch diagonal, with a display area of 5.04 inches horizontally by

Video Display Resolution 640 pixels horizontally by 480 pixels vertically Waveform Display Graticule Single Graticule: 401 × 501 pixels, 8 ×10 divisions, where divisions are 1 cm by 1 cm Waveform Display Colors Sixteen colors in infinite-persistence or variable persistence display with color coding

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

User can specify: field rate, number of lines, sync pulse width and polarity, line rate, and vertical interval timing.

3.78 inches vertically

1–11

Nominal Traits

T able 1–7: Nominal Traits — GPIB Interface, Output Ports, and Power Fuse

Name Description

Interface, GPIB GPIB interface complies with IEEE Std 488-1987 Interface, RS-232 RS-232 interface complies with EIA/TIA 574 (talk only) Interface, Centronics Centronics interface complies with Centronics interface standard C332-44 Feb 1977,

REV A Interface, Video VGA video output with levels that comply with EIA RS 343A standard. DB-15 connector Logic Polarity for Main- and Delayed-

Trigger Outputs Fuse Rating Either of two fuses1 may be used: a 0.25I × 1.25I (UL 198.6, 3AG): 6 A FAST, 250 V or

Each fuse type requires its own fuse cap.

Negative TRUE. High to low transition indicates the trigger occurred.

a 5 mm × 20 mm (IEC 127): 5 A (T), 250V.

T able 1–8: Nominal Traits — Data Handling and Reliability

Name Description

Time, Data-Retention, Nonvolatile

Memory

Floppy disk 3.5 inch, 720 K or 1.44 Mbyte, DOS 3.3-or-later compatible

The times that reference waveforms, stored setups, and calibration constants are retained.

Data is maintained by small lithium-thionyl-chloride batteries internal to the memory ICs. The amount of lithium is so small in these ICs that they can typically be safely disposed of with ordinary garbage in a sanitary landfill.

Battery life ≥ 5 years

1–12

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

Nominal Traits

T able 1–9: Nominal Traits — Mechanical

Name Description

Cooling Method Forced-air circulation with no air filter. Clearance is required. Construction Material Chassis parts constructed of aluminum alloy; front panel constructed of plastic laminate;

circuit boards constructed of glass laminate. Cabinet is aluminum and is clad in Tektronix

Blue vinyl material. Finish Type T ektronix Blue vinyl-clad aluminum cabinet Weight Standard Digitizing Oscilloscope

14.1 kg (31 lbs), with front cover.

24.0 kg (53 lbs), when packaged for domestic shipment

Rackmount Digitizing Oscilloscopes

14.1 kg (31 lbs) plus weight of rackmount parts, for the rackmounted Digitizing Oscilloscopes (Option 1R).

Rackmount conversion kit

2.3 kg (5 lbs), parts only; 3.6 kg (8 lbs), parts plus package for domestic shipping

Overall Dimensions Standard Digitizing Oscilloscope

Height: 193 mm (7.6 in), with the feet installed Width: 445 mm (17.5 in), with the handle Depth: 434 mm (17.1 in), with the front cover installed

Rackmount Digitizing Oscilloscope

Height: 178 mm (7.0 in) Width: 483 mm (19.0 in) Depth: 558.8 mm (22.0 in)

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

1–13

Nominal Traits

1–14

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

W arranted Characteristics

This section lists the various warranted characteristics that describe the TDS 684A and 7XXA Digitizing Oscilloscopes. Electrical and environmental characteristics are included.

Warranted characteristics are described in terms of quantifiable performance limits which are warranted.

NOTE. In these tables, those warranted characteristics that are checked in the procedure Performance Verification appear in boldface type under the column

Name.

As stated above, this section lists only warranted characteristics. A list of typical characteristics starts on page 1–21.

Performance Conditions

The performance limits in this specification are valid with these conditions: H The oscilloscope must have been calibrated/adjusted at an ambient tempera-

ture between +20

H The oscilloscope must be in an environment with temperature, altitude,

humidity, and vibration within the operating limits described in these specifications.

H The oscilloscope must have had a warm-up period of at least 20 minutes. H The oscilloscope must have had its signal-path-compensation routine last

executed after at least a 20 minute warm-up period at an ambient temperature within ±5

_ C of the current ambient temperature.

_ C and +30_ C.

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

1–15

Warranted Characteristics

Accuracy, Offset Analog Bandwidth, DC-50 Coupled

Analog Bandwidth, DC-50 Coupled and Bandwidth selection is FULL

Analog Bandwidth, DC-50  Coupled

selection is FULL

T able 1–10: Warranted Characteristics — Signal Acquisition System

Name Description Accuracy, DC Gain TDS 684A: ±1.5% for all sensitivities from 2 mV/div to 10 V/div

± 2.0% at 1 mV/div sensitivity

TDS 7XXA: ±1% for all sensitivities from 1 mV/div to 10 V/div with offset from 0 V to

±100V

Volts/Div Setting

1 mV/div – 100 mV/div

TDS 684A Offset Accuracy

±((0.2% ×

)

| Net Offset

| + 1.5 mV + (0.6 div x V/div))

TDS 744A Offset Accuracy

±((0.2% × | Net Offset

|) + 1.5 mV + (0.1 div x V/div setting))

TDS 784A Offset Accuracy

±((0.2% × | Net Offset

|) + 1.5 mV + (0.1 div x V/div setting))

with P6245 Probe and Bandwidth selection is FULL

101 mV/div – 1 V/div

±((0.25% × | Net Offset

)

+ 15 mV +

1.01 V/div – 10 V/div

(0.6 div x V/div)) ±((0.25% ×

| Net Offset

1 | )

+ 150 mV + ( 0.6 div x V/div))

Volts/Div 684A Bandwidth

10 mV/div –

DC – 1 GHz

1 V/div 5 mV/div –

DC – 750 MHz

9.95 mV/div 2 mV/div –

DC – 600 MHz

4.98 mV/div 1 mV/div –

DC – 500 MHz

1.99 mV/div

Volts/Div as Read Out on Screen

10 mV/div –

684A Bandwidth

(Not Applicable)

100 V/div

±((0.25% ×

| Net Offset

|) + 15 mV + (0.1 div x V/div setting))

±((0.25% × | Net Offset

|) + 150 mV + (0.1 div x V/div setting))

744A Bandwidth

DC – 500 MHz

DC – 450 MHz

744A Bandwidth

(Not Applicable)

±((0.25% ×

| Net Offset

|) + 15 mV + (0.1 div x V/div setting))

±((0.25% × | Net Offset

|) + 150 mV + (0.1 div x V/div setting))

784A Bandwidth

DC – 1 GHz

DC – 750 MHz

DC – 600 MHz

DC – 500 MHz

784A Bandwidth

(Not Applicable)

1–16

100 mV/div – 10 V/div

50 mV/div –

99.5 mV/div 20 mV/div –

49.8 mV/div 10 mV/div –

19.9 mV/div

DC – 1 GHz

DC – 750 MHz

DC – 600 MHz

DC – 500 MHz

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

DC – 500 MHz

DC – 450 MHz

DC – 1 GHz

DC – 750 MHz

DC – 600 MHz

DC – 500 MHz

T able 1–10: Warranted Characteristics — Signal Acquisition System (Cont.)

Analog Bandwidth, DC-1M  Coupled

selection is FULL

Name Description

Volts/Div as with P6139A Probe and Bandwidth selection is FULL

Read Out on

Screen

10 mV/div –

100 V/div

684A Bandwidth

500 MHz

744A Bandwidth

500 MHz

Warranted Characteristics

784A Bandwidth

500 MHz

100 mV/div –

500 MHz

10 V/div

50 mV/div –

500 MHz

99.5 mV/div

20 mV/div –

500 MHz

49.8 mV/div

10 mV/div –

400 MHz

450 MHz

500 MHz

19.9 mV/div

Crosstalk (Channel Isolation) ≥100:1 at 100 MHz and ≥30:1 at the rated bandwidth for any two channels having equal

Volts/Div settings

Delay Between Channels, Full Bandwidth

TDS 684A: ≤100 ps for any two channels with equal Volts/Div and Coupling settings

TDS 744A/784A: ≤50 ps for any two channels with equal Volts/Div and Coupling settings Input Impedance, DC–1 M Coupled 1 M ±0.5% in parallel with 10 pF ±3 pF Input Impedance, DC–50  Coupled

Input Voltage, Maximum, DC–1M,

50  ±1% with VSWR ≤1.3:1 from DC – 500 MHz, ≤1.5:1 from 500 MHz – 1 GHz

±400 V (DC + peak AC); derate at 20 dB/decade above 1 MHz AC–1 M, or GND Coupled

Input Voltage, Maximum, DC-50 or

5 V

, with peaks ≤ ±30 V

RMS

AC–50  Coupled Lower Frequency Limit, AC Coupled TDS 684A: ≤10 Hz when AC–1 M Coupled; ≤200 kHz when AC–50  Coupled

Net Offset = Offset – (Position × Volts/Div). Net Offset is the nominal voltage level at the oscilloscope input that

corresponds to the center of the A-D converter’s dynamic range. Offset Accuracy is the accuracy of this voltage level.

The limits given are for the ambient temperature range of 0_C to +30_C. Reduce the upper bandwidth frequencies by 5 MHz for the TDS 684A or by 2.5 MHz for the TDS 7XXA for each _C above +30_C.

The AC Coupled Lower Frequency Limits are reduced by a factor of 10 when 10X passive probes are used.

T able 1–11: Warranted Characteristics — Time Base System

Name Description Accuracy, Long Term Sample Rate and

Delay Time

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

TDS 684A: ±100 ppm over any ≥1 ms interval

TDS 7XXA: ±25 ppm over any ≥1 ms interval

1–17

Warranted Characteristics

Sensitivity, Edge-Type T rigger, Coupling

Sensitivity, Edge-Type T rigger, Coupling set to “DC”

Accuracy (Time) for Pulse-Glitch or

Accuracy (Time) for Pulse-Glitch or Pulse-Width Triggering

Logic Levels, Main- and Delayed-Trigger

Logic Levels, Main- and Delayed-Trigger Outputs

Output Voltage and Frequency,

Output Voltage and Frequency, Probe Compensator

T able 1–12: Warranted Characteristics — Triggering System

Name Description

Trigger Source Sensitivity

Any Channel

Auxiliary

Time Range Accuracy

1 ns to 1 ms

TDS 684A: 0.35 division from DC to 50 MHz, increasing to 1 division at 1 GHz TDS 7XXA: 0.35 division from DC to 50 MHz, increasing to 1 division at 500 MHz for the TDS 744A or to 1 division at 1 GHz for the TDS 784A

TDS 684A or 784A: 250 mV from DC to 50 MHz, increasing to 500 mV at 100 Mhz TDS 744A: 400 mV from DC to 50 MHz, increasing to 750 mV at 100 Mhz

±(20% of setting + 0.5 ns)

1.02 ms to 1 s

Input Signal Sync Amplitude for Stable Triggering, NTSC and PAL modes (Option 05 Video Trigger)

Jitter (Option 05 Video Trigger) 60 ns

The minimum sensitivity for obtaining a stable trigger. A stable trigger results in a uniform, regular display triggered on

Field selection “Odd”, “Even”, or “All”: 0.6 division to 4 divisions Field selection “Numeric”: 1 division to 4 divisions (NTSC mode)

on NTSC or PAL signal

p-p

±(100 ns + 0.01% of Setting)

the selected slope. The trigger point must not switch between opposite slopes on the waveform, and the display must not “roll” across the screen on successive acquisitions. The TRIG’D LED stays constantly lighted when the SEC/DIV setting is 2 ms or faster but may flash when the SEC/DIV setting is 10 ms or slower.

T able 1–13: Warranted Characteristics — Output Ports, Probe Compensator, and Power Requirements

Name Description

Characteristic Limits

Vout (HI) Vout (LO)

Characteristic Limits

Output Voltage

≥2.5 V open circuit; ≥1.0 V into a 50 W load to ground

≤0.7 V into a load of ≤4 mA; ≤0.25 V into a 50 W load to ground

0.5 V (base-top) ±1% into a ≥50 W load

Output Voltage, Signal Out (CH 31) For TDS 684A: 20 mV/division ±20% into a 1 MW load;

Source Voltage 90 to 250 VAC Source Frequency 45 Hz to 440 Hz

1–18

Frequency

1 kHz ±5%

10 mV/division ±20% into a 50 W load

For TDS 7XXA: 22 mV/division ±20% into a 1 MW load;

11 mV/division ±20% into a 50W load

, continuous range

RMS

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

Warranted Characteristics

T able 1–13: Warranted Characteristics — Output Ports, Probe Compensator, and Power Requirements (Cont.)

Name Description

Power Consumption ≤300 W (450 VA)

CH 3 signal out is present at the rear panel if CH 3 is selected as the trigger source for the main and/or delayed trigger systems. It is not available when a channel other than CH3 is the source for the Video Trigger when Option 05 is installed.

T able 1–14: Warranted Characteristics — Environmental

Name Description

Atmospherics Temperature (no diskette in floppy drive):

TDS 684A: Operating: +4_ C to +45_ C TDS 7XXA: Operating: +4_ C to +50_ C Nonoperating: –22_ C to +60_ C

Relative humidity (no diskette in floppy drive):

Operating: 20% to 80%, at or below +32_ C, upper limit derates to 30% relative humidity at +45_ C

Nonoperating: 5% to 90%, at or below +41_ C, upper limit derates to 30% relative humidity at 60_ C

Altitude:

To 4570 m (15,000 ft.), operating To 12190 m (40,000 ft.), nonoperating

Dynamics Random vibration (floppy diskette not installed):

0.31 g rms, from 5 to 500 Hz, 10 minutes each axis, operating

3.07 g rms, from 5 to 500 Hz, 10 minutes each axis, nonoperating

Emissions

Meets or exceeds the requirements of the following standards:

Vfg. 243/1991 Amended per Vfg. 46/1992 FCC Code of Federal Regulations, 47 CFR, Part 15, Subpart B, Class A European Community Requirements

EN 55011 Class A Radiated Emissions EN 55011 Class A Conducted Emissions EN 50081–1

EN60555–2 Power Line Harmonic Emissions

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

1–19

Warranted Characteristics

T able 1–14: Warranted Characteristics — Environmental (Cont.)

Name Description

Susceptibility

Third Party Certification Conforms to and is certified where appropriate to:

VGA output cable needs to be terminated, if connected at all, for the Instrument to meet these standards. The test will pass with LCOM part # CTL3VGAMM–5.

The GPIB cable connected to the instrument for certain of the emissions tests must be “low EMI” having a high-quality outer shield connected through a low impedance to both connector housings. Acceptable cables are Tektronix part numbers 012-0991-00, -01, -02, and -03. In order to maintain the EMI performance conforming to the above regulations, the following cables, or their equivalent, should be used: a shielded Centronics cable, 3 meters in length, part number 012-1214-00, and a shielded RS-232 cable, 2.7 meters in length, CA part number 0294-9.

Meets or exceeds the EMC requirements of the following standards:

EN 50082–1 European Community Requirements

IEC 801-2 Electrostatic Discharge

IEC 801-3 Radiated Susceptibility

IEC 801-4 Fast Transients

IEC 801-5 AC Surge

UL 1244 CSA–C22.2 No. 231

1–20

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

Typical Characteristics

Calculated Rise Time

This subsection contains tables that list the various typical characteristics which describe the TDS 684A and 7XXA Digitizing Oscilloscopes.

Typical characteristics are described in terms of typical or average performance. Typical characteristics are not warranted.

T able 1–15: Typical Characteristics — Signal Acquisition System

Name Description Accuracy, Delta Time Measurement The limits are given in the following table for signals having amplitude greater than

5 divisions, reference level = 50%, filter set to (sinX/X), acquired at 5 mV/div or greater.

For the TDS 7XXA, pulse duration < 10 div. Channel skew not included.

For the Single Shot condition, 1.4 ≤ T

the displayed rise time.

TDS 684A: For the averaged condition, 1.4 ≤ T

Interval, as described elsewhere in these specifications.

TDS 684A: Extra error in the measurement will occur for two-channel measurements due

to channel-to-channel skew . This is described elsewhere in these specifications.

Conditions Time Measurement Accuracy

Single Shot or Sample

mode (or HiRes mode

on the TDS 7XXA),

Full Bandwidth se-

lected

≥ 100 Averages, Full

Bandwidth selected.

TDS 7XXA: repetitive

Volts/Div Setting 684A Rise Time

10 mV/div – 1 V/div

TDS 684A:±( (0.20 × sample interval) + (100 ppm × | Reading |) + (0.05 × W

TDS 684A example: at 5 GS/s, 5 ns/div, measuring a 40 ns wide pulse, accuracy = ±( 40 ps + 4 ps + 5 ps) = ±49 ps.

TDS 7XXA: ±≥ 0.15 sample interval + 25 ppm × | Reading | + t/div/1000

TDS 7XXA example: at 4 Gs/s, accuracy = 37.5 ps TDS 684A: ±( 10 ps + (100 ppm × | Reading |) + (0.25 × Wi ) )

TDS 7XXA: 20 ps + (25 ppm × | Reading |) + t/div/1000

450 ps

≤ 4, where Si is the sample interval and Tr is

r/Si

≤ 40, where Wi is the Waveform

r/Wi

) )

744A Rise Time

800 ps

784A Rise Time

400 ps

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

5 mV/div – 9.95 mV/

div

2 mV/div – 4.98 mV/

div

1 mV/div – 1.99 mV/

div

600 ps

750 ps

900 ps

800 ps

890 ns

530 ps

600 ns

800 ns

1–21

Typical Characteristics

Effective Bits — TDS 684A

Effective Bits — TDS 744A

Input Frequency

The chart on the right gives the typical

9.2 divisions at 1 MHz, 50 mV/div @ 25° C

Effective Bits — TDS 784A

Input Frequency

effective bits for a sine wave adjusted to Step Response Settling Errors

Step Response Settling Errors

Volts/Div Setting

Step Amplitude

T able 1–15: Typical Characteristics — Signal Acquisition System (Cont.)

Name Description

Input Frequency Effective Bits

The chart on the right gives the typical effective bits for a 9-division p-p sine-wave input, 50 mV/div, 10 ns/div (5 GS/s), with a record length of 1000 points:

98 MHz 245 MHz 490 MHz

6.3 bits

6.0 bits

5.5 bits

The chart on the right gives the typical effective bits for a sine wave adjusted to

The chart on the right gives the typical

9.2 divisions at 1 MHz, 50 mV/div @ 25° C

Frequency Limit, Upper, 250 MHz Bandwidth Limited

Frequency Limit, Upper , 20 MHz Bandwidth Limited

990 MHz

5.2 bits

Sample Rate 2 GS/s 10 MS/s & HiRes

1 MHz – 9.2 divs 6.8 bits 9.7 bits 500 MHz 6.8 bits N/A

Sample Rate 4 GS/s 10 MS/s & HiRes

1 MHz – 9.2 divs 6.6 bits 9.7 bits 500 MHz – 8.5 divs 6.6 bits N/A 1 GHz – 6.5 divs 5.5 bits N/A

250 MHz

20 MHz

1 mV/div – 100 mV/div 101 mV/div – 1 V/div

≤2 V ≤20 V

Settling Error (%)

20 ns 100 ns 20 ms

0.5%

1.0%

0.2%

0.5%

0.1%

0.2%

The numbers given are valid 0_C to +30_C and will increase as the temperature increases due to the degradation in bandwidth. Rise time is calculated from the bandwidth. It is defined by the following formula:

TDS 684ARise Time (ns) 

Note that if you measure rise time, you must take into account the rise time of the test equipment (signal source, etc.) that you use to provide the test signal. That is, the measured rise time (RT and the rise time of the test signal source (RTgen) according to the following formula:

 RT

 RT

The values given are the maximum absolute difference between the value at the end of a specified time interval after the midlevel crossing of the step and the value one second after the midlevel crossing of the step, expressed as a percentage of the step amplitude.

1–22

gen

1.01 V/div – 10 V/div

450

BW (MHz)

≤200 V

TDS 7XXA Rise Time (ns) 

) is determined by the instrument rise time (RTi)

1.0%

400

BW (MHz)

0.5%

0.2%

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

T able 1–16: Typical Characteristics — T riggering System

Accuracy , Trigger Level or Threshold,

Accuracy , Trigger Level or Threshold, DC Coupled

Trigger Position Error ,

Trigger Position Error , Edge Triggering Sensitivity, Edge Trigger, Not DC Coupled

Name Description

Trigger Source Accuracy

(for signals having rise and fall times ≥ 20 ns)

Any Channel

Typical Characteristics

±((2% × | Setting – Net Offset |) + (0.3 div × Volts/div Setting ) + Offset Accuracy)

Input, Auxiliary Trigger

Holdoff, V ariable, Main Trigger

Lowest Frequency for Successful Operation of “Set Level to 50%” Function

Sensitivities, Logic Trigger and Events Delay , DC Coupled

Sensitivities, Pulse-T ype Runt Trigger

Sensitivities, Pulse-T ype Trigger Width and

Glitch

Auxiliary

Not calibrated or specified

The input resistance is ≥1.5 kW; the maximum safe input voltage is

±20 V (DC + peak AC).

Acquisition Mode Trigger-Position Error

Sample, Average

Envelope

±(1 Waveform Interval + 1 ns) ±(2 Waveform Intervals + 1 ns)

1,2

For all Time/Division ranges, the minimum holdof f is 250 ns and the maximum holdof f is

12 seconds. The minimum resolution is 8 ns for settings ≤ 1.2 ms.

30 Hz

Trigger Source Typical Signal Level for Stable

Triggering

Same as the DC-coupled limits for frequencies above 60 Hz. Attenuates

signals below 60 Hz. Noise Reject High Frequency Reject

Three times the DC-coupled limits.

One and one-half times the DC-coupled

limits from DC to 30 kHz. Attenuates

signals above 30 kHz. Low Frequency Reject

One and one-half times the DC-coupled

limits for frequencies above 80 kHz.

Attenuates signals below 80 kHz.

1.0 division, from DC to 500 MHz, at vertical settings > 10 mV/div and ≤ 1 V/div at the BNC input

1.0 division, at vertical settings > 10 mV/div and ≤ 1 V/div at the BNC input

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Typical Characteristics

Width, Minimum Pulse and Rearm, for

Width, Minimum Pulse and Rearm, for Pulse Triggering

The minimum pulse widths and rearm

Pulse-Type triggering.

T able 1–16: Typical Characteristics — T riggering System (Cont.)

Name Description

Width, Minimum Pulse and Rearm, for

For vertical settings > 10 mV/div and ≤ 1 V/div at the BNC input

Logic Triggering or Events Delay

Minimum

Triggering Type

Minimum Pulse Width

Minimum Re-Arm Width

Time Between Channels

Logic Not Applicable 1 ns 1 ns Events Delay 1 ns (for either + or

Not Applicable 2 ns

– pulse widths)

For vertical settings > 10 mV/div. and 3 1 V/div at the BNC input

Minimum Pulse

The minimum pulse widths and rearm widths and transition times

required for

Pulse Class

Glitch 1 ns 2 ns + 5% of Glitch Width Setting

Width

Minimum Re-Arm Width

Runt 2 ns 2 ns Time-Qualified Runt 2 ns 8.5 ns + 5% of Width Setting Width 1 ns 2 ns + 5% of Width Upper Limit Setting

8.5 ns + 5% of Delta Time Setting

Input Signal Sync Amplitude for Stable

Slew Rate 600 ps All field selections: 0.6 division to 4 divisions

Triggering, HDTV and FLEXFMT modes (Option 05 Video Trigger)

Jitter for HDTV mode

17 ns

p-p

(Option 05 Video Trigger)

Sync Width Flex Format and HDTV

min. 400 ns

modes (Option 05 Video Trigger) Sync Duty Cycle, Flex Format and HDTV

min. 50 to 1

modes (Option 05 Video Trigger) Hum Rejection

(Option 05 Video Trigger)

The trigger position errors are typically less than the values given here. These values are for triggering signals having a

NTSC and PAL: –20 dB without any trigger spec deterioration. Triggering will continue down to 0 dB with some performance deterioration.

slew rate at the trigger point of ≥ 0.5 division/ns.

The waveform interval (WI) is the time between the samples in the waveform record. Also, see the footnote for the characteristics Sample Rate Range or Interpolated Waveform Rates in Table 1–4, on page 1–10.

The minimum sensitivity for obtaining a stable trigger. A stable trigger results in a uniform, regular display triggered on the selected slope. The trigger point must not switch between opposite slopes on the waveform, and the display must not “roll” across the screen on successive acquisitions. The TRIG’D LED stays constantly lighted when the SEC/DIV setting is 2 ms or faster but may flash when the SEC/DIV setting is 10 ms or slower.

The minimum signal levels required for stable logic or pulse triggering of an acquisition, or for stable counting of a DC-coupled, events-delay signal. Also, see the footnote for Sensitivity, Edge-T ype T rigger, DC Coupled in this table. (Stable counting of events is counting that misses no events and produces no extra, phantom events.)

The minimum signal levels required for stable runt pulse triggering of an acquisition. Also, see the footnote for Sensitivity, Edge-T ype T rigger, DC Coupled in this table. (Stable counting of events is counting that misses no events.)

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Typical Characteristics

T able 1–16: Typical Characteristics — T riggering System (Cont.)

Name Description

The minimum signal levels required for stable pulse width or glitch triggering of an acquisition. Also, see the footnote for Sensitivity, Edge-T ype T rigger, DC Coupled in this table. (Stable counting of events is counting that misses no events.)

For Logic, time between channels refers to the length of time a logic state derived from more than one channel must exist to be recognized. For Events, the time is the minimum time between a main and delayed event that will be recognized if more than one channel is used.

For Slew Rate Triggering, this is the minimum transition time, defined to be the time the user’s signal spends between the two trigger threshold settings.

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Typical Characteristics

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Installation

Supplying Operating Power

NOTE. Read all information and heed all warnings in this subsection before connecting the oscilloscope to a power source.

WARNING. AC POWER SOURCE AND CONNECTION. The oscilloscope operates from a single-phase power source. It has a three-wire power cord and two-pole, three-terminal grounding type plug. The voltage to ground (earth) from either pole of the power source must not exceed the maximum rated operating voltage, 250 volts.

Before making connection to the power source, be sure the digitizing oscilloscope has a suitable two-pole, three-terminal grounding-type plug.

GROUNDING. This instrument is safety Class 1 equipment (IEC designation). All accessible conductive parts are directly connected through the grounding conductor of the power cord to the grounded (earthing) contact of the power plug.

WARNING. The power input plug must be inserted only in a mating receptacle with a grounding contact where earth ground has been verified by a qualified service person. Do not defeat the grounding connection. Any interruption of the grounding connection can create an electric shock hazard.

For electric shock protection, the grounding connection must be made before making connection to the instrument’s input or output terminals.

Power Cord Information

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

A power cord with appropriate plug configuration is supplied with each Digitizing Oscilloscope. Table 2–1 gives the color-coding of the conductors in the power cord. If you require a power cord other than the one supplied, refer to Table 2–2, Power Cord Identification.

2–1

Installation

T able 2–1: Power-Cord Conductor Identification

Conductor Color Alternate Color

Ungrounded (Line) Brown Black Grounded (Neutral) Light Blue White Grounded (Earthing) Green/Y ellow Green

T able 2–2: Power Cord Identification

Plug Configuration Normal Usage Option Number

North America 125 V

Europe 230 V

United Kingdom 230 V

Australia 230 V

North America 230 V

Switzerland 230 V

Standard

2–2

Operating Voltage

This oscilloscope operates with any line voltage from 90–250 VAC

RMS

with any line frequency from 45–440 Hz. There are two fuses, either of which may be used throughout the line voltage and frequency ranges. (The two fuses are not totally interchangeable as each requires a different fuse cap.)

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Installation

Memory Backup Power

Operating Environment

Operating Temperature

Memory modules with on-board batteries allow the TDS 684A and 7XXA Digitizing Oscilloscopes to retain some types of data upon loss of the AC power source. The stored adjustment constants, saved front-panel settings, current front-panel settings (instrument status), and waveforms saved in memory are retained.

The on-board batteries of the memory modules have a shelf life of about five years. Partial or total loss of stored settings upon power on may indicate that the memory modules need to be replaced.

The following environmental requirements are provided to ensure proper operation and long instrument life.

Operate Digitizing Oscilloscopes where the ambient air temperature is from 4_ C to +45_ C (+50_ C for the TDS 7XXA) with no diskette in the floppy drive. Store the oscilloscopes in ambient temperatures from –22_ C to +60_ C with no diskette in the floppy drive. After storage at temperatures outside the operating limits, allow the chassis to stabilize at a safe operating temperature before applying power.

Ventilation Requirements

The Digitizing Oscilloscopes are cooled by air drawn in and exhausted through their cabinet side panels by an internal fan. To ensure proper cooling of the oscilloscope, allow at least two inches clearance on both sides and 3/4 inch on the bottom of the oscilloscope. (The feet on the bottom of the oscilloscope provide the required clearance when set on flat surfaces.) The top of the oscilloscope does not require ventilation clearance.

CAUTION. If air flow is restricted, the Digitizing Oscilloscopes’s power supply may temporarily shut down.

Applying and Interrupting Power

Consider the following information when you power on or power off the instrument, or when power is interrupted due to an external power failure.

Power On

Upon power on, the oscilloscope runs a power-on self check. If it passes, the oscilloscope displays a “passed” status message and a prompt to press CLEAR MENU to continue. If it fails, the oscilloscope displays a diagnostic log that identifies the area(s) that failed and a prompt to press CLEAR MENU to

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Installation

continue. See Section 6, Maintenance, for information on diagnostics and fault isolation.

Power Off

CAUTION. DO NOT power off the oscilloscope when either running a signal path compensation or when doing any of the adjustments described in Section 5, Adjustment Procedures. To do so might result in the loss of internally stored adjustment constants.

In general, do not power off the instrument when doing operations that affect the data types listed in Table 1–1. Wait for the instrument to finish the operation when doing adjustments, saving waveforms, or saving setups.

Improper power off or unexpected loss of power to the oscilloscope can result in the following corruptions of nonvolatile RAM (NVRAM). The following table describes the messages displayed when power is restored after an abnormal power off.

T able 2–3: Effects of Corrupted Data

Corrupted Data Type Results

Adjustment Constants:

Error Log Errors logged are lost Reference Waveforms Waveform Lost Saved Setups Setup Lost

Repackaging Instructions

Use a corrugated cardboard shipping carton having a test strength of at least 275 pounds and with an inside dimension at least six inches greater than the instrument dimensions.

If the instrument is being shipped to a Tektronix Service Center, enclose the following information: the owner’s address, name and phone number of a contact person, type and serial number of the instrument, reason for returning, and a complete description of the service required.

Signal Path Compensation A signal path compensation is required. Voltage Reference A voltage reference adjustment is required

(Section 5)

Frequency Response A frequency response adjustment is required

(Section 5)

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Installed Options

Installation

Seal the shipping carton with an industrial stapler or strapping tape. Mark the address of the Tektronix Service Center and also your own return

address on the shipping carton in two prominent locations.

Your instrument may be equipped with one or more instrument options. Except for the line-cord options described by Table 2–2 (on page 2–2 of this section), all options and optional accessories are listed and described in Section 7, Options. For further information and prices of instrument options, see your Tektronix Products catalog or contact your Tektronix Field Office.

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Installation

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

Operating Instructions

Before doing service, read the following operating instructions. These instructions are at the level appropriate for servicing these Digitizing Oscilloscopes. The User Manual contains more complete operating instructions.

Additional instructions are integrated into the service procedures found in later sections of this manual. For instance, the procedures found in the section Performance Verification contain instructions for making the front-panel settings required to check each instrument characteristic included there. Also, the general instructions for operating these Digitizing Oscilloscopes’ internal diagnostic routines are found in Section 6, Maintenance. You may also find the Product Description in Section 1 useful for understanding how the oscilloscope functions.

Screen Layout

Figure 2–1 on page 2–8 shows the screen layout. This figure illustrates a full graticule. You may also select a grid, crosshair, or frame graticule from the display menu.

Basic Procedures

How to Power On

Push the principal power switch found on the rear panel of the oscilloscope, then push the ON/STBY (standby) switch to toggle the oscilloscope into operation. The switch at the rear panel is the true power disconnect switch. The ON/ STBY(standby) switch simply toggles operation on and off.

WARNING. The principal power switch at the rear panel is the true power disconnect switch. The ON/STBY (standby) switch simply toggles operation on and off. When connected to a power source and when the principal power switch is on, the internal power supplies and much of the other circuitry of these Digitizing Oscilloscopes are energized regardless of the setting of the ON/STBY switch.

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Operating Instructions

Brief status

information

Graticule and waveforms

Waveform reference

symbols shows ground levels

and waveform sources

Vertical scale, horizontal scale,

and trigger level readouts

Pop-up menu

Position of waveform

record relative to

the screen and display

General purpose

knob readout

Side menu area. Readouts for measurements move here when CLEAR MENU is pressed.

How to Use Help

How to Use the Status

Main menu display area. Readouts in lower graticule

area move here when CLEAR MENU is pressed.

Figure 2–1: Map of Display Functions

Push the HELP front-panel button to enter help mode. Front-panel knobs and buttons now display information about their function when turned or pushed. Push HELP again to exit help mode.

To get help information on a menu item, display the menu desired (if you are in help mode, exit help first). Push HELP. Now the menu buttons display information about their function when pushed.

Push the SHIFT, then the STATUS front-panel buttons to display the status menu. You will find messages reflecting the state of the acquisition system, whether it is running or stopped (and if it is stopped, why), as well as setup-related information.

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Operating Instructions

How to Set Functions

Special function controls.

Access all functions except

vertical, horizontal, and

trigger functions from this

front-panel control block.

Most functions can be set either by using one (or two) front-panel button(s) or knob(s), or by pushing a front-panel button to use a main menu, and then a side-menu button to set the function. The following steps illustrate both procedures.

1. Locate the block that contains the function to be set.

Vertical function controls. Access all

vertical functions and inputs from

this front-panel control block.

Horizontal function controls.

Access all horizontal functions

from this front-panel block.

Trigger function controls. Access all trigger functions from this front-panel block.

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Operating Instructions

2. Select the waveform source(s). Position, scale, and set trigger level for

waveform source(s) directly from the front panel. The steps that follow provide examples of possible control selections.

123

2–10

a. Input waveforms into these channels (7). Example: CH 1. b. Push any channel’s button (8) to display its waveform. The last channel

turned on determines which waveform is positioned and scaled. The indicator above the channel last selected is lighted. Example: Push CH 1; then CH 2.

c. Vertically (1) and horizontally (2) scale and position the waveform(s)

selected. Example: Set the scale to 100 mV/div and center the waveform on screen.

d. Stop and start acquiring waveforms (3). Example: Push RUN/STOP if

not acquiring.

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Operating Instructions

e. Adjust trigger level (6) to trigger the waveform(s) selected or use these

buttons (5) to either set a trigger level at the mid-amplitude level of the selected waveform or to force a single trigger. Example: Push SET

LEVEL TO 50%.

3. Set all other functions using menus. a. Choose the waveform source (8) first if setting a vertical function; else

skip to step b. Example: Push CH 2.

b. Push SHIFT (4) if the function to be set is highlighted in blue; else skip

to step c.

10 11

c. Push the front-panel button that corresponds to the menu containing the

function. A main menu (14) for selecting among related functions appears. Example: Push VERTICAL MENU.

Note the two labels: the top label is a function to choose from; the bottom label tells you the current setting for that function. Offset is currently set to 0 V.

d. Select a function from the main menu using the main-menu buttons (12).

A side menu for selecting among that the available settings for that function appears. Example: Push Coupling (13).

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Operating Instructions

e. Select the setting for the function from the side menu (9) using the

side-menu buttons (11). Example: Push AC (10).

How to Set Complex

Functions

A few functions require more than just two levels (main and side) of menus to completely specify their settings. In such cases, either the main menu, the side menu, or both are modified to supply additional choices. The procedures that follow show both schemes.

1. Set up a function using pop-up menus:

a. For some selections, pushing a main-menu button pops up a menu (18)

of subfunctions. Example: Push Type (17). Note the pop-up menu for Type is set to Edge. All the main-menu

buttons to the right of the pop-up menu are labeled with subfunctions of

Edge.

b. Pushing the button that popped up the menu (17) toggles through the

pop-up menu choices. Example: Repeatedly push Type to toggle through the pop-up menu. Notice the other main-menu button labels change accordingly. Toggle back to Edge.

c. Complete the setting of the desired mode by selecting from the main

menu and the side menu that results. Example: Push Mode & Holdoff (16), and then push Normal (15).

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Operating Instructions

2. Set up a function using the general purpose knob (20). (The examples of possible menu selections in the substeps that follow assume you’ve pushed TRIGGER MENU.)

19 20

a. Pushing some main-menu buttons displays a side menu with labels

containing readouts that can be varied. Example: Push Level (21).

b. Pushing the side-menu button Level assigns the general purpose knob to

control the readout appearing in the button label. It also copies the readout to the general purpose knob readout area in the right corner of the screen. Example: Push Level (19).

c. Use the general purpose knob (20) to adjust the trigger level to the

setting desired. Example: Turn the knob to –20 mV.

More About the General Purpose Knob. As you’ve just seen, the general purpose knob can be used to extend the number of choices available to a side menu button. The general purpose knob can also be assigned to control the following functions:

H Cursor positioning H Display intensities H Delay time

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Operating Instructions

H Gated measurements H Number of events H Template generation H Trigger position H Holdoff H Offset H Variable persistence

In all cases, the menus are used to select the function to which the general purpose knob is assigned. The following attributes apply to this knob:

H Depending on the function it is assigned to control, the general purpose knob

may vary numerical readouts, position objects (cursors) on screen, or select between icon-label settings that show up in side-menu labels.

H The general purpose knob has a readout area at the upper right corner of the

screen. (See Figure 2–1.) This readout always reflects the name and value of the function that the general purpose knob is currently controlling.

H Whenever the general purpose knob assignment is changed, a knob icon

appears immediately to the left of the general purpose knob readout to notify you of the assignment change. The icon is removed as soon as you use the general purpose knob to change the value of the function it is assigned to.

H To assign the general purpose knob to control a function, display the menu

containing the function; then select the function. (Note that not all functions can be controlled by the general purpose knob.)

H Whenever the menu is removed, the general purpose knob is not assigned

and doesn’t control any function. (An exception is the cursor function. If cursors are turned on, removing the menu leaves the knob assigned to control the cursors until reassigned by selecting another menu and function that uses the knob.)

H When the SHIFT button is lighted, the general purpose knob becomes a

coarse adjustment. When the SHIFT button is not lighted, the general purpose knob becomes a fine adjustment.

H The general purpose knob also has a SELECT button. This button is used to

toggle the knob between the control of either of the two cursors displayed when H-bar or V-bar cursors are turned on in the cursor menu.

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Operating Instructions

Display and Utility Menus. Using the techniques described for using menus, you can access and change functions in the display menu and utilities menu. In the Display menu, you can set the following functions:

H Color: waveforms, readouts, graticule H Intensity: waveforms, readouts, graticule, etc. H Style of waveform display(s): vectors or dots, intensified or nonintensified

samples, and infinite or variable persistence

H Display format: XY or YT H Graticule format: type H Waveform interpolation filter and readout options

From the Utility menu, you can configure the GPIB port (talk/listen, address, etc.) and access internal routines for self diagnostics and self compensation. Instructions for setting up communication over the GPIB are found in Section 5, Adjustment Procedures.

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Operating Instructions

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Theory of Operation

This section describes the electrical operation of the TDS 684A and 7XXA Digitizing Oscilloscopes using the major circuit blocks or modules.

This section has two main parts: H Logic Conventions describes how logic functions are discussed and

represented in this manual.

H Module Overview describes circuit operation from a functional-circuit block

perspective.

Logic Conventions

The Digitizing Oscilloscopes contain many digital logic circuits. This manual refers to these circuits with standard logic symbols and terms. Unless otherwise stated, all logic functions are described using the positive-logic convention: the more positive of the two logic levels is the high (1) state, and the more negative level is the low (0) state. Signal states may also be described as “true” meaning their active state or “false” meaning their nonactive state. The specific voltages that constitute a high or low state vary among the electronic devices.

Module Overview

General

Input Signal Path

Active-low signals are indicated by a tilde prefixed to the signal name (~RESET). Signal names are considered to be either active-high, active-low, or to have both active-high and active-low states.

This module overview describes the basic operation of each functional circuit block as shown in Figure 9-2.

The TDS 684A and 7XXA Digitizing Oscilloscopes have four channels. Each channel provides a calibrated vertical scale factor.

A signal enters the oscilloscope through a probe connected to a BNC on the A10 Attenuator/Acquisition board.

Attenuators. Circuitry in the attenuator selects the input coupling, termination, and the attenuation factor. The processor system, by way of the acquisition system, controls the attenuators. For example, if 50 W input termination is

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Theory of Operation

selected and the input is overloaded, the processor system switches the input to the 1 MW position.

Probe Coding Interface. Probe coding interface signals pass through the attenuator portion of the A10 Attenuator/Acquisition to the acquisition system, where they are sensed and controlled.

Acquisition System. The acquisition system amplifies the input signals, samples them, converts them to digital signals, and controls the acquisition process under direction of the processor system. The acquisition system includes the trigger, acquisition timing, and acquisition mode generation and control circuitry.

V oltage Controlled Oscillator (VCO). Master clocks for the acquisition system are generated by the circuitry on the A10 Acquisition board. The circuitry makes up a phased locked loop. The master clock is divided down by the A10 Acquisition circuitry under control of the processor system.

D1 Bus. The acquisition system passes the digital values representing the acquired waveform through the A14 D1 Bus to the A11 DRAM Processor/Display board. This happens after a waveform acquisition is complete if the digital signal processor in the processor system requests the waveform.

Processor System. The processor system contains a 68020 microprocessor that controls the entire instrument. It includes the firmware. It also includes a GPIB interface. You can reprogram the firmware from a remote controller using the GPIB and an external software package.

The processor also includes a digital signal processor. This signal processor processes each waveform as directed by the system processor. Waveforms and any text to be displayed are passed on to the display system. The A11 DRAM Processor/Display board contains both the processor and display systems.

Display System. Text and waveforms are processed by different parts of the display circuitry. The display system sends the text and waveform information to the tube assembly as a video signal. The display system also generates and sends vertical (VSYNC) and horizontal (HSYNC) sync signals to the tube assembly. A VGA-compatible video output is at the rear of the TDS 684A and 7XXA.

3–2

Tube Assembly

All information (waveforms, text, graticules, and pictographs) is displayed by the A30/31/32 Display system. The A30 generates the high voltages necessary to drive the display tube. It also contains the video amplifier, horizontal oscillator, and the vertical and horizontal yoke driver circuitry.

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

Theory of Operation

Front Panel

Rear Panel

Low Voltage Power Supply

The processor system sends instructions to and receives information from the Front Panel Processor on the A12 Front Panel board. The Front Panel Processor reads the front-panel switches and potentiometers. Any changes in their settings are reported to the processor system. The Front Panel Processor also turns the LEDs on and off and generates the bell signal.

Front-panel menu switches are also read by the Front Panel Processor. The processor sends any changes in menu selections to the processor system. The ON/STBY switch is one of the menu switches. However, it is not read by the Front Panel Processor, but passes through the A12 Front Panel board and the A11 DRAM Processor/Display board to the low voltage power supply.

The front panel also generates the probe compensation signals SIGNAL and GND.

The GPIB connector provides access to stored waveforms, and allows external control of the oscilloscope.

You can make hardcopies on the GPIB, RS-232 and Centronics ports.

The low voltage power supply is a switching power converter with active power factor control. It supplies power to all of the circuitry in the oscilloscope.

Fan

The principal POWER switch, located on the rear panel, controls all power to the oscilloscope including the Low Voltage Power Supply. The ON/STBY switch, located on the front panel, also controls all of the power to the oscilloscope except for part of the circuitry in the Low Voltage Power Supply.

The power supply sends a power fail (~PF) warning to the processor system if the power is going down.

The fan provides forced air cooling for the oscilloscope. It connects to +25 V from the Low Voltage Power Supply by way of the A11 DRAM Processor/Display module.

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Theory of Operation

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Performance Verification Procedures

Two types of Performance Verification procedures can be performed on this product; Brief Procedures and Performance Tests. You may not need to perform all of these procedures, depending on what you want to accomplish.

H To rapidly confirm that the oscilloscope functions and was adjusted properly,

just do the brief procedures under Self Tests, which begin on page 4–5. Advantages: These procedures are quick to do, require no external

equipment or signal sources, and perform extensive functional and accuracy testing to provide high confidence that the oscilloscope will perform properly. They can be used as a quick check before making a series of important measurements.

H To further check functionality, first do the Self Tests just mentioned; then do

the brief procedures under Functional Tests that begin on page 4–7. Advantages: These procedures require minimal additional time to perform,

require no additional equipment other than a standard-accessory probe, and more completely test the internal hardware of the oscilloscope. They can be used to quickly determine if the oscilloscope is suitable for putting into service, such as when it is first received.

H If more extensive confirmation of performance is desired, do the Perform-

ance Tests, beginning on page 4–15, after doing the Functional and Self Tests

just referenced. Advantages: These procedures add direct checking of warranted specifica-

tions. They require more time to perform and suitable test equipment is required. (See Equipment Required beginning on page 4–16.)

If you are not familiar with operating this oscilloscope, read the TDS 684A, TDS

744A, & TDS 784A Reference (070-8999-XX) or the TDS 684A, TDS 744A, & TDS 784A User Manual (070-8991-XX). These contain instructions that will

acquaint you with the use of the front-panel controls and the menu system.

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Performance Verification Procedures

Conventions

Throughout these procedures the following conventions apply:

H Each test procedure uses the following general format:

H Each procedure consists of as many steps, substeps, and subparts as required

Title of Test Equipment Required Prerequisites Procedure

to do the test. Steps, substeps, and subparts are sequenced as follows:

1. First Step a. First Substep

H First Subpart H Second Subpart

b. Second Substep

2. Second Step

H In steps and substeps, the lead-in statement in italics instructs you what to

do, while the instructions that follow tell you how to do it, as in the example step below, “Initialize the oscilloscope” by doing “Press save/recall SETUP. Now, press the main-menu button...”.

Initialize the oscilloscope: Press save/recall SETUP. Now, press the main-menu button Recall Factory Setup; then the side-menu button OK Confirm Factory Init.

H Where instructed to use a front-panel button or knob, or select from a main

or side menu, or verify a readout or status message, the name of the button or knob appears in boldface type: “press SHIFT; then UTILITY, press the main-menu button System until Cal is highlighted in the pop-up menu. Verify that the status message is Pass in the main menu under the Voltage Reference label.”

STOP. The symbol at the left is accompanied by information you must read to do the procedure properly.

4–2

H Refer to Figure 4–1: “Main menu” refers to the menu that labels the seven

menu buttons under the display; “side menu” refers to the menu that labels

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Performance Verification Procedures

the five buttons to the right of the display. “Pop-up menu” refers to a menu that pops up when a main-menu button is pressed.

Brief status information

Graticule and waveforms

Waveform reference

symbols show ground levels

and waveform sources

Vertical scale, horizontal scale,

and trigger level readouts

Pop-up menu

Position of waveform

record relative to

the screen and display

General purpose

knob readout

Side menu area. Readouts for measurements move here when CLEAR MENU is pressed.

Figure 4–1: Map of Display Functions

Main menu display area. Readouts in lower graticule

area move here when CLEAR MENU is pressed.

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Performance Verification Procedures

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

Brief Procedures

Self Tests

The Self Tests use internal routines to confirm basic functionality and proper adjustment. No test equipment is required to do these test procedures.

The Functional Tests utilize the probe-compensation output at the front panel as a test-signal source for further verifying that the oscilloscope functions properly. A probe, such as the P6245, is required to do these test procedures.

This procedure uses internal routines to verify that the oscilloscope functions and was adjusted properly. No test equipment or hookups are required.

Verify Internal Adjustment,

Self Compensation, and

Diagnostics

Equipment Required

Prerequisites Power on the Digitizing Oscilloscope and allow a 20 minute warm-up

1. Verify that internal diagnostics pass: Do the following substeps to verify

passing of internal diagnostics.

a. Display the System diagnostics menu:

H Press SHIFT; then press UTILITY. H Repeatedly press the main-menu button System until Diag/Err is

highlighted in the pop-up menu.

b. Run the System Diagnostics:

H First disconnect any input signals from all four channels. H Press the main-menu button Execute; then press the side-menu

button OK Confirm Run Test.

c. Wait: The internal diagnostics do an exhaustive verification of proper

oscilloscope function. This verification will take up to three and a half minutes on some models. At some time during the wait, a “clock” icon (shown at left) will appear on-screen. When the verification is finished, the resulting status will appear on the screen.

None

before doing this procedure.

d. Confirm no failures are found: Verify that no failures are found and

reported on-screen.

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Brief Procedures

e. Confirm the three adjustment sections have passed status:

H Press SHIFT; then press UTILITY. H Highlight Cal in the pop-up menu by repeatedly pressing the

main-menu button System. See Figure 4–2.

H Verify that the word Pass appears in the main menu under the

following menu labels: Voltage Reference, Frequency Response, and Pulse Trigger. See Figure 4–2.

f. Run the signal-path compensation: Press the main-menu button Signal

Path; then press the side-menu button OK Compensate Signal Paths.

g. Wait: Signal-path compensation may take five minutes on the

TDS 7XXA or fifteen minutes on the 684A to run. While it progresses, a “clock” icon (shown at left) is displayed on-screen. When compensation completes, the status message will be updated to Pass or Fail in the main menu. See step h.

h. Confirm signal-path compensation returns passed status: Verify that the

word Pass appears under Signal Path in the main menu. See Figure 4–2.

4–6

Highlight Cal

Verify Pass

Figure 4–2: Verifying Adjustments and Signal-Path Compensation

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

Functional Tests

Brief Procedures

2. Return to regular service: Press CLEAR MENU to exit the system menus.

The purpose of these procedures is to confirm that the oscilloscope functions properly. The only equipment required is one of the standard-accessory probes and, to check the file system, a 3.5 inch, 720 K or 1.44 Mbyte floppy disk.

CAUTION. The optional P6245 probes that can be used with this oscilloscope provide an extremely low loading capacitance (<1 pF) to ensure the best possible signal reproduction. These probes should not be used to measure signals exceeding ±8 volts, or errors in signal measurement will be observed. Above 40 volts, damage to the probe may result. To make measurements beyond ±10 volts, use either the P6139A probe (good to 500 volts), or refer to the catalog for a recommended probe.

STOP. These procedures verify functions; that is, they verify that the oscilloscope features operate. They do not verify that they operate within limits.

Therefore, when the instructions in the functional tests that follow call for you to verify that a signal appears on-screen “that is about five divisions in amplitude” or “has a period of about six horizontal divisions,” etc., do NOT interpret the quantities given as limits. Operation within limits is checked in Performance Tests, which begin on page 4–15.

STOP. DO NOT make changes to the front-panel settings that are not called out in the procedures. Each verification procedure will require you to set the oscilloscope to certain default settings before verifying functions. If you make changes to these settings, other than those called out in the procedure, you may obtain invalid results. In this case, just redo the procedure from step 1.

When you are instructed to press a menu button, the button may already be selected (its label will be highlighted). If this is the case, it is not necessary to press the button.

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Brief Procedures

Verify All Input Channels

Equipment Required

Prerequisites None

One probe such as the P6245 or P6139A

1. Install the test hookup and preset the oscilloscope controls: a. Hook up the signal source: Install the probe on CH 1. Connect the probe

tip to PROBE COMPENSATION SIGNAL on the front panel; connect the probe ground (typically black) to PROBE COMPENSA- TION GND. If using a P6245 probe, you may want to attach a Y-lead connector and two SMD KlipChips as shown in Figure 4–3.

4–8

Signal Gnd

Figure 4–3: Universal Test Hookup for Functional Tests – TDS 684A Shown

b. Initialize the oscilloscope:

H Press save/recall SETUP. H Press the main-menu button Recall Factory Setup. H Press the side-menu button OK Confirm Factory Init.

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

Brief Procedures

2. Verify that all channels operate: Do the following substeps — test CH 1

first, skipping substep a and b since CH 1 is already set up for verification

and as the trigger source from step 1. a. Select an unverified channel:

H Press WAVEFORM OFF to remove the channel just verified from

display.

H Press the front-panel button that corresponds to the channel you are

to verify.

H Move the probe to the channel you selected.

b. Match the trigger source to the channel selected:

H Press TRIGGER MENU. H Press the main-menu button Source. H Press the side-menu button that corresponds to the channel selected

(Ch2, Ch3, or Ch4).

c. Set up the selected channel:

H Set the vertical SCALE to 200 mV. H Set the horizontal SCALE to 200 ms. Press CLEAR MENU to

remove any menu that may be on the screen.

d. Verify that the channel is operational: Confirm that the following

statements are true. H The vertical scale readout for the channel under test shows a setting

of 200 mV, and a square-wave probe-compensation signal about

2.5 divisions in amplitude is on-screen. See Figure 4–1 on page 4–3 to locate the readout.

H The vertical POSITION knob moves the signal up and down the

screen when rotated.

H Turning the vertical SCALE knob counterclockwise decreases the

amplitude of the waveform on-screen, turning the knob clockwise increases the amplitude, and returning the knob to 200 mV returns the amplitude to about 2.5 divisions.

e. Verify that the channel acquires in all acquisition modes: Press SHIFT;

then press ACQUIRE MENU. Use the side menu to select, in turn, each of the three hardware acquire modes and confirm that the following statements are true. Refer to the icons at the left of each statement as you confirm those statements.

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Brief Procedures

H Sample mode displays an actively acquiring waveform on-screen.

(Note that there is noise present on the peaks of the square wave.)

H Peak Detect mode (TDS 7XXA only) displays an actively acquiring

waveform on-screen with the noise present in Sample mode “peak detected.”

H Hi Res mode (TDS 7XXA only) displays an actively acquiring

waveform on-screen with the noise that was present in Sample mode reduced.

H Envelope mode displays an actively acquiring waveform on-screen

with the noise displayed.

H Average mode displays an actively acquiring waveform on-screen

with the noise reduced.

f. Test all channels: Repeat substeps a through e until all four input

channels are verified.

3. Remove the test hookup: Disconnect the probe from the channel input and the probe-compensation terminals.

Verify the Time Base

Equipment Required

Prerequisites None

One probe such as the P6245 or P6139A

1. Install the test hookup and preset the oscilloscope controls: a. Hook up the signal source: Install the probe on CH 1. Connect the probe

tip to PROBE COMPENSATION SIGNAL on the front panel; connect the probe ground to PROBE COMPENSATION GND. See Figure 4–3 on page 4–8.

b. Initialize the oscilloscope:

H Press save/recall SETUP. H Press the main-menu button Recall Factory Setup; then press the

side-menu button OK Confirm Factory Init.

c. Modify default settings:

H Set the vertical SCALE to 200 mV. H Set the horizontal SCALE to 200 ms.

4–10

H Press CLEAR MENU to remove the menus from the screen.

2. Verify that the time base operates: Confirm the following statements.

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

Brief Procedures

a. One period of the square-wave probe-compensation signal is about five

horizontal divisions on-screen for the 200 ms horizontal scale setting (set in step 1c).

b. Rotating the horizontal SCALE knob clockwise expands the waveform

on-screen (more horizontal divisions per waveform period), counterclockwise rotation contracts it, and returning the horizontal scale to 200 ms returns the period to about five divisions.

c. The horizontal POSITION knob positions the signal left and right

on-screen when rotated.

3. Remove the test hookup: Disconnect the probe from the channel input and

the probe-compensation terminals.

Verify the Main and

Delayed Trigger Systems

Equipment Required

Prerequisites None

One probe such as the P6245 or P6139A

1. Install the test hookup and preset the oscilloscope controls: a. Hook up the signal source: Install the probe on CH 1. Connect the probe

tip to PROBE COMPENSATION SIGNAL on the front panel; connect the probe ground to PROBE COMPENSATION GND. See Figure 4–3 on page 4–8.

b. Initialize the oscilloscope:

H Press save/recall SETUP. H Press the main-menu button Recall Factory Setup. H Press the side-menu button OK Confirm Factory Init.

c. Modify default settings:

H Set the vertical SCALE to 200 mV. H Set the horizontal SCALE for the M (main) time base to 200 ms. H Press TRIGGER MENU. H Press the main-menu button Mode & Holdoff. H Press the side-menu button Normal. H Press CLEAR MENU to remove the menus from the screen.

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Brief Procedures

2. Verify that the main trigger system operates: Confirm that the following

statements are true. H The trigger level readout for the main trigger system changes with the

trigger-LEVEL knob.

H The trigger-LEVEL knob can trigger and untrigger the square-wave

signal as you rotate it. (Leave the signal untriggered, which is indicated by the display not updating.)

H Pressing SET LEVEL TO 50% triggers the signal that you just left

untriggered. (Leave the signal triggered.)

3. Verify that the delayed trigger system operates: a. Select the delayed time base:

H Press HORIZONTAL MENU. H Press the main-menu button Time Base. H Press the side-menu button Delayed Triggerable; then press the

side-menu button Delayed Only.

H Set the horizontal SCALE for the D (delayed) time base to 200 ms.

b. Select the delayed trigger level menu:

H Press SHIFT; then press DELAYED TRIG. H Press the main-menu button Level; then press the side-menu button

Level.

c. Confirm that the following statements are true:

H The trigger-level readout for the delayed trigger system changes as

you turn the general purpose knob.

H As you rotate the general purpose knob, the square-wave probe-com-

pensation signal can become triggered and untriggered. (Leave the signal untriggered, which is indicated by the display not updating.)

H Pressing the side-menu button Set to 50% triggers the probe-com-

pensation signal that you just left untriggered. (Leave the signal triggered.)

d. Verify the delayed trigger counter:

4–12

H Press the main-menu button Delay by Time. H Use the keypad to enter a delay time of 1 second. Press 1, then press

ENTER.

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

Brief Procedures

H Verify that the trigger READY indicator on the front panel flashes

about once every second as the waveform is updated on-screen.

4. Remove the test hookup: Disconnect the probe from the channel input and

the probe-compensation terminals.

Verify the File System

Equipment Required

Prerequisites None

One probe such as the P6245 or P6139A One 720 K or 1.44 Mbyte, 3.5 inch DOS-compatible disk.

You can use a disk of your own or you can use the Programming Examples Software 3.5 inch disk (Tektronix part number 063-1134-XX) contained in the TDS Family Programmer Manual (Tektronix part number 070-8709-XX).

1. Install the test hookup and preset the oscilloscope controls: a. Hook up the signal source: Install the probe on CH 1. Connect the probe

tip to PROBE COMPENSATION SIGNAL on the front panel; connect the probe ground to PROBE COMPENSATION GND. See Figure 4–3 on page 4–8.

b. Insert the test disk: Insert the disk in the disk drive to the left of the

monitor.

H Position the disk so the metal shutter faces the drive. H Position the disk so the stamped arrow is on the top right side. In

other words, place the angled corner in the front bottom location.

H Push the disk into the drive until it goes all the way in and clicks

into place.

c. Initialize the oscilloscope:

H Press save/recall SETUP. H Press the main-menu button Recall Factory Setup. H Press the side-menu button OK Confirm Factory Init.

d. Modify default settings:

H Set the vertical SCALE to 200 mV. H Set the horizontal SCALE for the M (main) time base to 200 ms.

Notice the waveform on the display now shows two cycles instead of five.

H Press CLEAR MENU to remove the menus from the screen.

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Brief Procedures

e. Save the settings:

H Press SETUP. H Press the main-menu button Save Current Setup; then press the

side-menu button To File.

H Turn the general purpose knob to select the file to save. Choose

 (or ). With this choice, you will save a file starting with , then containing 5-numbers, and a  extension. For example, the first time you run this on a blank, formatted disk or on the Example Programs Disk, the oscilloscope will assign the name  to your file. If you ran the procedure again, the oscilloscope would increment the name and call the file .

H Press the side-menu button Save To Selected File.

2. Verify the file system works:

H Press the main-menu button Recall Factory Setup and the side-menu

button OK Confirm Factory Init to restore the 500 ms time base and the five cycle waveform.

H Press the main-menu button Recall Saved Setup; then press the

side-menu button From File.

H Turn the general purpose knob to select the file to recall. For example, if

you followed the instructions above and used a blank disk, you had the oscilloscope assign the name TEK00000.SET to your file.

H Press the side-menu button Recall From Selected File. H Verify that Digitizing Oscilloscope retrieved the saved setup from the

disk. Do this by noticing the horizontal SCALE for the M (main) time base is again 200 ms and the waveform shows only two cycles just as it was when you saved the setup.

3. Remove the test hookup:

H Disconnect the probe from the channel input and the probe-compensa-

tion terminals.

H Remove the disk from the disk drive. Do this by pushing in the tab at the

bottom of the disk drive.

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

Performance Tests

This section contains a collection of procedures for checking that the TDS 684A and 7XXA Digitizing Oscilloscopes perform as warranted.

The procedures are arranged in four logical groupings: Signal Acquisition System

Checks, Time Base System Checks, Triggering System Checks, and Output Ports Checks. They check all the characteristics that are designated as checked in Specifications. (The characteristics that are checked appear in boldface type under Warranted Characteristics in Specifications.)

STOP. These procedures extend the confidence level provided by the basic procedures described on page 4–5. The basic procedures should be done first, then these procedures performed if desired.

Prerequisites

The tests in this section comprise an extensive, valid confirmation of performance and functionality when the following requirements are met:

H The cabinet must be installed on the Digitizing Oscilloscope. H You must have performed and passed the procedures under Self Tests, found

on page 4–5, and those under Functional Tests, found on page 4–7.

H A signal-path compensation must have been done within the recommended

calibration interval and at a temperature within ±5_ C of the present operating temperature. (If at the time you did the prerequisite Self Tests, the temperature was within the limits just stated, consider this prerequisite met.)

H The Digitizing Oscilloscope must have been last adjusted at an ambient

temperature between +20_ C and +30_ C, must have been operating for a warm-up period of at least 20 minutes, and must be operating at an ambient temperature between +4_ C and either +45_ C for the TDS 684A or +50_ C for the TDS 7XXA. (The warm-up requirement is usually met in the course of meeting the first prerequisite listed above.)

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Performance Tests

Equipment Required

T able 4–1: Test Equipment

Item Number and Description

These procedures use external, traceable signal sources to directly check warranted characteristics. The required equipment list follows this introduction.

Minimum Requirements Example Purpose

1. Attenuator ,10X (two required)

Ratio: 10X; impedance 50 ; connectors: female BNC input, male BNC

Tektronix part number 01 1-0059-02

output

2. Attenuator , 5X Ratio: 5X; impedance 50 ; connec-

tors: female BNC input, male BNC

Tektronix part number 01 1-0060-02

output

3. Adapter, BNC female to Clip Leads

4. Terminator, 50  Impedance 50 ; connectors: female

5. Cable, Precision 50  Coaxial (two required)

6. Connector , Dual-Banana (two required)

BNC female to Clip Leads Tektronix part number

013-0076-00 Tektronix part number

BNC input, male BNC output 50 , 36 in, male to male BNC

connectors

01 1-0049-01 Tektronix part number

012-0482-00

Female BNC to dual banana Tektronix part number

103-0090-00

7. Connector , BNC “T” Male BNC to dual female BNC Tektronix part number

103-0030-00

8. Coupler, Dual-Input Female BNC to dual male BNC Tektronix part number

067-0525-02

9. Generator , DC Calibration

10. Generator , Calibration 500 mV square wave calibrator

Variable amplitude to ±104 V; accuracy to 0.1%

Data Precision 8200 Checking DC Offset, Gain,

Tektronix PG 506A

amplitude; accuracy to 0.25%

11. Generator , Leveled Sine Wave,

200 kHz to 250 MHz; Variable amplitude from 5 mV to 4 V

into 50 

p-p

Tektronix SG 503 Leveled Sine Wave Generator

Medium-Frequency

12. Generator, Leveled Sine Wave, High-Frequency

13. Generator, Time Mark Variable marker frequency from 10 ms

14. Probe, 10X A P6139A or P6245 probe

250 MHz to 1 GHz; Variable amplitude from 500 mV to 4 V

into 50 ;

p-p

6 MHz reference

to 10 ns; accuracy within 2 ppm

Tektronix SG 504 Leveled Sine Wave Generator SG 504 Output Head

Tektronix TG 501A Time Mark Generator

Tektronix part number P6139A or P6245

with

Signal Attenuation

Signal Coupling for Probe Compensator Output Check

Signal Termination for Channel Delay Test

Signal Interconnection

Various Accuracy Tests

Checking Trigger Sensitivity

Checking Delay Between Channels

and Measurement Accuracy To check accuracy of CH 3

Signal Out Checking Trigger Sensitivity

at low frequencies

Checking Analog Bandwidth and Trigger Sensitivity at high frequencies

Checking Sample-Rate and Delay-time Accuracy

Signal Interconnection

4–16

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

T able 4–1: Test Equipment (Cont.)

Item Number and Description

Performance Tests

PurposeExampleMinimum Requirements

15. 3.5 inch, 720 K or

1.44 Mbyte, DOS-compatible floppy disk

16. Generator, Video Signal Provides PAL compatible outputs Tektronix TSG 121 Used to Test Video Option 05

17. Oscillator , Leveled Sine wave Generator

18. Pulse Generator Tektronix part number PG 502 Used to Test Video Option 05

19. Cable, Coaxial (two required)

20. Terminator, 75  (two required)

Requires a TM 500 or TM 5000 Series Power Module Mainframe.

Warning: The optional P6245 probes that may be used with this oscilloscope provide an extremely low loading capacitance (<1 pF) to ensure the best possible signal reproduction. These probes should not be used to measure signals exceeding ±8 V , or errors in signal measurement will be observed. Above 40 V, damage to the probe may result. To make measurements beyond ±8 V, use either the P6139A probe (good to 500 V), or refer to the catalog for a recommended probe.

60 Hz. Sine wave Tektronix part number SG 502 Used to Test Video Option 05

75 , 36 in, male to male BNC connectors

Impedance 75 ; connectors: female BNC input, male BNC output

Programming Examples Software Disk (Tektronix part number 063-1134-XX) that comes with the TDS Family Programmer Manual (Tektronix part number 070-8709-XX)

Tektronix part number 012-1338-00

Tektronix part number 01 1-0102-01

Checking File System Basic Functionality

Equipped Instruments Only

Equipped Instruments Only Used to Test Video Option 05

Equipped Instruments Only

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Performance Tests

4–18

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

Performance Tests

TDS 684A Test Record

Photocopy this and the next three pages and use them to record the performance test results for your TDS 684A.

TDS 684A T est Record

Instrument Serial Number: Certificate Number: Temperature: RH %: Date of Calibration: Technician:

TDS 684A Performance Test Minimum Incoming Outgoing Maximum

Offset Accuracy CH1 Offset +1 mV

+101 mV +1.01 V

CH2 Offset +1 mV

+101 mV +1.01 V

CH3 Offset +1 mV

+101 mV +1.01 V

CH4 Offset +1 mV

+101 mV

+1.01 V DC Voltage Measurement Accuracy (Averaged) CH1 5 mV Vert scale setting,

–5 Div position setting, +1 V offset

CH1 5 mV Vert scale setting,

+5 Div position setting, –1 V offset

CH1 200 mV Vert scale setting,

–5 Div position setting, +10 V offset

CH1 200 mV Vert scale setting,

+5 Div position setting, –10 V offset

CH1 1 V Vert scale setting,

–5 Div position setting, +10 V offset

CH1 1 V Vert scale setting,

+5 Div position setting, –10 V offset

CH2 5 mV Vert scale setting,

–5 Div position setting, +1 V offset

CH2 5 mV Vert scale setting,

+5 Div position setting, –1 V offset

CH2 200 mV Vert scale setting,

–5 Div position setting, +10 V offset

– 1.45 mV – 69.1 mV – 691 mV

+ 1.029 V __________ __________ + 1.0513 V

– 1.0513 V __________ __________ – 1.029 V

+ 11.420 V __________ __________ + 11.786 V

– 11.786 V __________ __________ – 11.420 V

+ 17.26 V __________ __________ + 18.76 V

– 18.76 V __________ __________ – 17.26 V

+ 1.029 V __________ __________ + 1.0513 V

– 1.0513 V __________ __________ – 1.029 V

+ 11.420 V __________ __________ + 11.786 V

__________ __________ __________

+ 1.45 mV + 69.1 mV + 691 mV

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Performance Tests

TDS 684A T est Record (Cont.)

Instrument Serial Number: Certificate Number: Temperature: RH %: Date of Calibration: Technician:

TDS 684A Performance Test MaximumOutgoingIncomingMinimum

CH2 200 mV Vert scale setting,

+5 Div position setting, –10 V offset

CH2 1 V Vert scale setting,

–5 Div position setting, +10 V offset

CH2 1 V Vert scale setting,

+5 Div position setting, –10 V offset

CH3 5 mV Vert scale setting,

–5 Div position setting, +1 V offset

CH3 5 mV Vert scale setting,

+5 Div position setting, –1 V offset

CH3 200 mV Vert scale setting,

–5 Div position setting, +10 V offset

CH3 200 mV Vert scale setting,

+5 Div position setting, –10 V offset

CH3 1 V Vert scale setting,

–5 Div position setting, +10 V offset

CH3 1 V Vert scale setting,

+5 Div position setting, –10 V offset

CH4 5 mV Vert scale setting,

–5 Div position setting, +1 V offset

CH4 5 mV Vert scale setting,

+5 Div position setting, –1 V offset

CH4 200 mV Vert scale setting,

–5 Div position setting, +10 V offset

CH4 200 mV Vert scale setting,

+5 Div position setting, –10 V offset

CH4 1 V Vert scale setting,

–5 Div position setting, +10 V offset

CH4 1 V Vert scale setting,

+5 Div position setting, –10 V offset Analog Bandwidth CH1 100 mV 424 mV __________ __________ N/A CH2 100 mV 424 mV __________ __________ N/A CH3 100 mV 424 mV __________ __________ N/A CH4 100 mV 424 mV __________ __________ N/A

– 11.786 V __________ __________ – 11.420 V

+ 17.26 V __________ __________ + 18.76 V

– 18.76 V __________ __________ – 17.26 V

+ 1.029 V __________ __________ + 1.0513 V

– 1.0513 V __________ __________ – 1.029 V

+ 11.420 V __________ __________ + 11.786 V

– 11.786 V __________ __________ – 11.420 V

+ 17.26 V __________ __________ + 18.76 V

– 18.76 V __________ __________ – 17.26 V

+ 1.029 V __________ __________ + 1.0513 V

– 1.0513 V __________ __________ – 1.029 V

+ 11.420 V __________ __________ + 11.786 V

– 11.786 V __________ __________ – 11.420 V

+ 17.26 V __________ __________ + 18.76 V

– 18.76 V __________ __________ – 17.26 V

4–20

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

Performance Tests

TDS 684A T est Record (Cont.)

Instrument Serial Number: Certificate Number: Temperature: RH %: Date of Calibration: Technician:

TDS 684A Performance Test MaximumOutgoingIncomingMinimum

Delay Between Channels Delay Between Channels N/A __________ __________ 100 ps Time Base System Long Term Sample Rate/

Delay Time @ 500 ns/10 ms Trigger System Accuracy Pulse-Glitch or Pulse-Width,

Hor. scale ≤ 1 ms

Lower Limit Upper Limit

Pulse-Glitch or Pulse-Width, Hor. scale > 1 ms

Lower Limit

Upper Limit Main Trigger, DC Coupled, Positive Slope 9.863 V __________ __________ 10.137 V Main Trigger, DC Coupled, Negative Slope 9.863 V __________ __________ 10.137 V Delayed Trigger, DC Coupled, Positive Slope 9.863 V __________ __________ 10.137 V Delayed Trigger, DC Coupled, Negative Slope 9.863 V __________ __________ 10.137 V CH1 Sensitivity, 50 MHz, Main Pass/Fail __________ __________ Pass/Fail CH1 Sensitivity , 50 MHz, Delayed Pass/Fail __________ __________ Pass/Fail CH1 AUX Trigger Input Pass/Fail __________ __________ Pass/Fail CH1 Sensitivity, 1 GHz, Main Pass/Fail __________ __________ Pass/Fail CH1 Sensitivity, 1 GHz, Delayed Pass/Fail __________ __________ Pass/Fail Output Signal Checks MAIN TRIGGER OUTPUT, 1 MW

High

Low MAIN TRIGGER OUTPUT, 50 W

High

Low DELA YED TRIGGER OUTPUT, 50 W

DELA YED TRIGGER OUTPUT, 1 MW

–2.0 Div __________ __________ +2.0 Div

2.5 ns

1 ms 1 ms

High ≥ 2.5 V __________

High ≥ 1.0 V __________

High ≥ 2.5 V __________

__________ __________

__________

__________ __________

7.5 ns

3 ms 3 ms

Low ≤ 0.7 V

Low ≤ 0.25 V

Low ≤ 0.7 V

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Performance Tests

TDS 684A T est Record (Cont.)

Instrument Serial Number: Certificate Number: Temperature: RH %: Date of Calibration: Technician:

TDS 684A Performance Test MaximumOutgoingIncomingMinimum

CH 3 SIGNAL OUTPUT, 1 M Pk-Pk ≥ 80 mV __________ __________ Pk-Pk ≤ 120 mV CH 3 SIGNAL OUTPUT, 50  Pk-Pk ≥ 40 mV __________ __________ Pk-Pk ≤ 60 mV Probe Compensator Output Signal Frequency (CH1 Freq.) 950 Hz __________ __________ 1.050 kHz Voltage (difference) 495 mV __________ __________ 505 mV

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

Performance Tests

TDS 7XXA Test Record

Photocopy this and the next three pages and use them to record the performance test results for your TDS 7XXA.

TDS 7XXA T est Record

Instrument Serial Number: Certificate Number: Temperature: RH %: Date of Calibration: Technician:

TDS 7XXA Performance Test Minimum Incoming Outgoing Maximum

Offset Accuracy CH1 Offset +1 mV

+101 mV +1.01 V

CH2 Offset +1 mV

+101 mV +1.01 V

CH3 Offset +1 mV

+101 mV +1.01 V

CH4 Offset +1 mV

+101 mV

+1.01 V DC Voltage Measurement Accuracy (Averaged) CH1 5 mV Vert scale setting,

–5 Div position setting, +1 V offset

CH1 5 mV Vert scale setting,

+5 Div position setting, –1 V offset

CH1 200 mV Vert scale setting,

–5 Div position setting, +10 V offset

CH1 200 mV Vert scale setting,

+5 Div position setting, –10 V offset

CH1 1 V Vert scale setting,

–5 Div position setting, +10 V offset

CH1 1 V Vert scale setting,

+5 Div position setting, –10 V offset

CH2 5 mV Vert scale setting,

–5 Div position setting, +1 V offset

CH2 5 mV Vert scale setting,

+5 Div position setting, –1 V offset

CH2 200 mV Vert scale setting,

–5 Div position setting, +10 V offset

– 1.6 mV – 25.1 mV – 251 mV

+ 1.0355 V __________ __________ + 1.0445 V

– 1.0445 V __________ __________ – 1.0355 V

+ 11.5385 V __________ __________ + 11.6615 V

– 11.6615 V __________ __________ – 11.5385 V

+ 17.7785 V __________ __________ + 18.2215 V

– 18.2215 V __________ __________ – 17.7785 V

+ 1.0355 V __________ __________ + 1.0445V

– 1.0445 V __________ __________ – 1.0355 V

+ 11.5385 V __________ __________ + 11.6615 V

__________ __________ __________

+ 1.6 mV + 25.1 mV + 251 mV

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

4–23

Performance Tests

TDS 7XXA T est Record (Cont.)

Instrument Serial Number: Certificate Number: Temperature: RH %: Date of Calibration: Technician:

TDS 7XXA Performance Test MaximumOutgoingIncomingMinimum

CH2 200 mV Vert scale setting,

+5 Div position setting, –10 V offset

CH2 1 V Vert scale setting,

–5 Div position setting, +10 V offset

CH2 1 V Vert scale setting,

+5 Div position setting, –10 V offset

CH3 5 mV Vert scale setting,

–5 Div position setting, +1 V offset

CH3 5 mV Vert scale setting,

+5 Div position setting, –1 V offset

CH3 200 mV Vert scale setting,

–5 Div position setting, +10 V offset

CH3 200 mV Vert scale setting,

+5 Div position setting, –10 V offset

CH3 1 V Vert scale setting,

–5 Div position setting, +10 V offset

CH3 1 V Vert scale setting,

+5 Div position setting, –10 V offset

CH4 5 mV Vert scale setting,

–5 Div position setting, +1 V offset

CH4 5 mV Vert scale setting,

+5 Div position setting, –1 V offset

CH4 200 mV Vert scale setting,

–5 Div position setting, +10 V offset

CH4 200 mV Vert scale setting,

+5 Div position setting, –10 V offset

CH4 1 V Vert scale setting,

–5 Div position setting, +10 V offset

CH4 1 V Vert scale setting,

– 11.6615 V __________ __________ – 11.5385 V

+ 17.7785 V __________ __________ + 18.2215 V

– 18.2215 V __________ __________ – 17.7785 V

+ 1.0355 V __________ __________ + 1.0445 V

– 1.0445 V __________ __________ – 1.0355 V

+ 11.5385 V __________ __________ + 11.6615 V

– 11.6615 V __________ __________ – 11.5385 V

+ 17.7785 V __________ __________ + 18.2215 V

– 18.2215 V __________ __________ – 17.7785 V

+ 1.0355 V __________ __________ + 1.0445 V

– 1.0445 V __________ __________ – 1.0355 V

+ 11.5385 V __________ __________ + 11.6615 V

– 11.6615 V __________ __________ – 11.5385 V

+ 17.7785 V __________ __________ + 18.2215 V

– 18.2215 V __________ __________ – 17.7785 V

4–24

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

Tektronix 684A, 744A User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Service Manual

Table of Contents

Specifications

Operational Information

Theory of Operation

Performance Verification

Adjustment Procedures

Maintenance

Options Electrical Parts List Diagrams Mechanical Parts LIst

List of Figures

List of Tables

General Safety Summary

Injury Precautions

Product Damage Precautions

Safety Terms and Symbols

Certifications and Compliances

Service Safety Summary

Preface

Manual Structure

Manual Conventions

Related Manuals

Introduction

Service Strategy

Service Offerings

Before You Begin

Specifications

Product Description

User Interface

Signal Acquisition System

Horizontal System

Trigger System

Acquisition Control

On-Board User Assistance

Measurement Assistance

Storage

Display

Nominal Traits

W arranted Characteristics

Performance Conditions

Typical Characteristics

Installation

Supplying Operating Power

Operating Environment

Applying and Interrupting Power

Repackaging Instructions

Installed Options

Operating Instructions

Screen Layout

Basic Procedures

Theory of Operation

Logic Conventions

Module Overview

Performance Verification Procedures

Conventions

Brief Procedures

Self Tests

Functional Tests

Performance Tests

Prerequisites

Equipment Required

TDS 684A Test Record

TDS 7XXA Test Record