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
Copyright T ektronix, Inc. 1994, 1995. All rights reserved.
T ektronix products are covered by U.S. and foreign patents, issued and pending. Information in this publication supercedes
that in all previously published material. Specifications and price change privileges reserved.
Printed in the U.S.A.
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.
Table of Contents
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
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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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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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
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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. . . . . . . . . . . . . . . . . . . . . . . . . .
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Table of Contents
Figure 6–16: A11 Processor/Display Removal 6–37. . . . . . . . . . . . . . . . . . .
Figure 6–17: Board Bracket Removal 6–38. . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–18: A10 Acquisition Board Removal 6–41. . . . . . . . . . . . . . . . . . .
Figure 6–19: Floppy Disk Removal 6–43. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–20: Rear Chassis Removal 6–45. . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–21: A16 Low Voltage 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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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TDS 684A, TDS 744A, & TDS 784A Service Manual
List of Tables
Table of Contents
Table 1–1: Key Features of the TDS 684A and 7XXA Oscilloscopes 1–1
Table 1–2: Record Length vs. Divisions per Record, Samples per
Division and Sec/Div Sequence 1–3. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 1–3: Nominal Traits — Signal Acquisition System 1–9. . . . . . . . . .
Table 1–4: Nominal Traits — Time Base System 1–10. . . . . . . . . . . . . . . .
Table 1–5: Nominal Traits — Triggering System 1–10. . . . . . . . . . . . . . . .
Table 1–6: Nominal Traits — Display System 1–11. . . . . . . . . . . . . . . . . . .
Table 1–7: Nominal Traits — GPIB Interface, Output Ports, and
Power Fuse 1–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 1–8: Nominal Traits — Data Handling and Reliability 1–12. . . . . .
Table 1–9: Nominal Traits — Mechanical 1–13. . . . . . . . . . . . . . . . . . . . . .
Table 1–10: Warranted Characteristics
— Signal Acquisition System 1–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 1–11: Warranted Characteristics — Time Base System 1–17. . . . . .
Table 1–12: Warranted Characteristics — Triggering System 1–18. . . . .
Table 1–13: Warranted Characteristics — Output Ports, Probe
Compensator, and Power Requirements 1–18. . . . . . . . . . . . . . . . . . . .
Table 1–14: Warranted Characteristics — Environmental 1–19. . . . . . . .
Table 1–15: Typical Characteristics — Signal Acquisition System 1–21. .
Table 1–16: Typical Characteristics — Triggering System 1–23. . . . . . . .
Table 2–1: Power-Cord Conductor Identification 2–2. . . . . . . . . . . . . . . .
Table 2–2: Power Cord Identification 2–2. . . . . . . . . . . . . . . . . . . . . . . . .
Table 2–3: Effects of Corrupted Data 2–4. . . . . . . . . . . . . . . . . . . . . . . . . .
Table 4–1: Test Equipment 4–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 4–2: DC Offset Accuracy (Zero Setting) 4–28. . . . . . . . . . . . . . . . . .
Table 4–3: DC Accuracy 4–31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 4–4: Analog Bandwidth 4–35. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 5–1: Calibration Tests 5–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 5–2: Adjustments Required for Module Replaced 5–4. . . . . . . . . .
Table 5–3: Adjustments and Dependencies 5–4. . . . . . . . . . . . . . . . . . . . .
Table 5–4: Test Equipment, Fixtures, and Supplies 5–5. . . . . . . . . . . . . .
Table 5–5: GPIB Board Configuration 5–7. . . . . . . . . . . . . . . . . . . . . . . . .
Table 6–1: Relative Susceptibility to Static-Discharge Damage 6–3. . . . .
TDS 684A, TDS 744A, & TDS 784A Service Manual
vii
Table of Contents
Table 6–2: External Inspection Check List 6–5. . . . . . . . . . . . . . . . . . . . .
Table 6–3: Internal Inspection Check List 6–6. . . . . . . . . . . . . . . . . . . . . .
Table 6–4: Tools Required for Module Removal 6–11. . . . . . . . . . . . . . . . .
Table 6–5: Normal Supply Voltages (Measured on J26 and J27 on
the A11 DRAM Processor/Display Module) 6–63. . . . . . . . . . . . . . . . . .
Table 6–6: No-Load Supply Voltages (Measured on J5 and J6 on
the A17 Main LV Power Supply Module) 6–63. . . . . . . . . . . . . . . . . . . .
Table 7–1: Options 7–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 7–2: Standard Accessories 7–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 7–3: Optional Accessories 7–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 7–4: Accessory Software 7–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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.
ix
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.
x
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
xi
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
xiv
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
xv
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.
xx
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
xxi
Introduction
xxii
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
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