Tektronix 1502C Service Manual
Service Manual
1502C
Metallic Time-Domain Reflectometer
070-7168-04
This document applies to firmware version 5.02
and above.
Warning
The servicing instructions are for use by qualified
personnel only. To avoid personal injury, do not
perform any servicing unless you are qualified to
do so. Refer to all safety summaries prior to
performing service.
www.tektronix.com
Copyright © T ektronix, Inc. 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.
T ektronix, Inc., P.O. Box 500, Beaverton, OR 97077
TEKTRONIX and TEK are registered trademarks of T ektronix, Inc.
WARRANTY
T ektronix warrants that the products that it manufactures and sells will be free from defects in materials and workmanship
for a period of one (1) year from the date of shipment. If a 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; c) to repair any damage or malfunction
caused by the use of non-T ektronix supplies; or d) to service a product that has been modified or integrated with other
products when the effect of such modification or integration increases the time or difficulty of servicing the product.
THIS WARRANTY IS GIVEN BY TEKTRONIX IN LIEU OF ANY OTHER WARRANTIES, EXPRESS OR
IMPLIED. TEKTRONIX AND ITS VENDORS DISCLAIM ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. TEKTRONIX’ RESPONSIBILITY TO
REP AIR OR REPLACE DEFECTIVE PRODUCTS IS THE SOLE AND EXCLUSIVE REMEDY PROVIDED TO
THE CUSTOMER FOR BREACH OF THIS WARRANTY. TEKTRONIX AND ITS VENDORS WILL NOT BE
LIABLE FOR ANY INDIRECT , SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES IRRESPECTIVE
OF WHETHER TEKTRONIX OR THE VENDOR HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH
DAMAGES.
Table of Contents
General Safety Summary xi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Service Safety Summary xiii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General Information xv. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation and Repacking xvi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Contacting T ektronix xviii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating Instructions
Operating Instructions 1–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Overview 1–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Preparing to Use the 1502C 1–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Display 1–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front-Panel Controls 1–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Menu Selections 1–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
T est Preparations 1–11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cable T est Procedure 1–13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Additional Features (Menu Selected) 1–26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operator Performance Checks
Operator Performance Checks 2–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Specifications
Specifications 3–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical Characteristics 3–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Environmental Characteristics 3–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Certifications and Compliances 3–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Physical Characteristics 3–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Options and Accessories
Options and Accessories 4–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Option 04: YT–1 Chart Recorder 4–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Option 05: Metric Default 4–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Option 07: YT–1S Chart Recorder 4–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Cord Options 4–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Accessories 4–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit Descriptions
Circuit Descriptions 5–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Introduction 5–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Supply 5–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1502C MTDR Service Manual
i
Table of Contents
Processor System 5–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Option Port Interface 5–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Video Processor 5–13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Timebase 5–15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Driver/Sampler 5–23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Panel 5–25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Display Module 5–28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Calibration and Adjustments
Calibration 6–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Introduction 6–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Calibration Performance Check 6–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Display Module Check 6–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Panel Check 6–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Horizontal Scale (Timebase) Check 6–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Zero Offset Check 6–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Vertical Position (Offset) Check 6–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Noise Check 6–13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sampling Efficiency Check 6–15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Offset/Gain Check 6–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
RAM/ROM Check 6–17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Aberrations Check 6–17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Risetime Check 6–19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Jitter Check 6–21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Option 04/07: YT-1/YT -1S Chart Recorder Check 6–23. . . . . . . . . . . . . . . . . . . . . . .
Option 05: Metric Default Check 6–23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Adjustment Procedures 6–25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Visual Inspection 6–26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Supply Checks and Adjustments 6–26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Main Board ”12 VDC Check and Adjust 6–30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Impedance Check 6–35. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LCD Check and Adjustment 6–36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Zero Offset Adjust 6–39. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
After Adjustments are Completed 6–41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance
ii
Maintenance 7–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Introduction 7–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Preventive Maintenance 7–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Part Removal and Replacement 7–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Troubleshooting 7–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Control Panel Installation 7–17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installing the Case Cover Over the Chassis 7–19. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1502C MTDR Service Manual
Replaceable Electrical Parts
Replaceable Electrical Parts 8–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Parts Ordering Information 8–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Diagrams
Diagrams 9–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General Information 9–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Replaceable Mechanical Parts
Replaceable Mechanical Parts 10–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Parts Ordering Information 10–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using the Replaceable Mechanical Parts List 10–1. . . . . . . . . . . . . . . . . . . . . . . . . . .
Glossary and Index
Table of Contents
1502C MTDR Service Manual
iii
Table of Contents
List of Figures
Figure 1–1: Rear Panel Voltage Selector, Fuse, AC Receptacle 1–1. . . . .
Figure 1–2: Display Showing Low Battery Indication 1–4. . . . . . . . . . . .
Figure 1–3: 1502C Front-Panel Controls 1–5. . . . . . . . . . . . . . . . . . . . . .
Figure 1–4: Display and Indicators 1–6. . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1–5: Vp Set at .30, Cursor Beyond Reflected Pulse
(Set Too Low) 1–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1–6: Vp Set at .99, Cursor Less Than Reflected Pulse
(Set Too High) 1–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1–7: Vp Set at .66, Cursor at Reflected Pulse (Set Correctly) 1–12
Figure 1–8: 20-ft Cable at 5 ft/div 1–13. . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1–9: Short in the Cable 1–13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1–10: Open in the Cable 1–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1–11: 455-ft Cable 1–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1–12: 455-ft Cable 1–15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1–13: Reflection Adjusted to One Division in Height 1–15. . . . . . .
Figure 1–14: Return Loss 1–17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1–15: Ohms-at-Cursor 1–17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1–16: Display with VIEW INPUT Turned Off 1–18. . . . . . . . . . . . .
Figure 1–17: Display of a Stored Waveform 1–19. . . . . . . . . . . . . . . . . . . .
Figure 1–18: Display of a Stored Waveform 1–19. . . . . . . . . . . . . . . . . . . .
Figure 1–19: Waveform Moved to Top Half of Display 1–20. . . . . . . . . . . .
Figure 1–20: Current Waveform Centered, Stored Waveform Above 1–20.
Figure 1–21: Current Waveform Center, Stored Waveform Above,
Difference Below 1–21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1–22: Waveform of Three-Foot Lead-in Cable 1–22. . . . . . . . . . . . .
Figure 1–23: Cursor Moved to End of Three-Foot Lead-in Cable 1–22. . . .
Figure 1–24: Cursor Moved to End of Three-Foot Lead-in Cable 1–23. . . .
Figure 1–25: Cursor Moved to 0.00 ft 1–23. . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1–26: Incident Pulse at Three Divisions 1–24. . . . . . . . . . . . . . . . . .
Figure 1–27: Waveform of Short 75W Cable 1–24. . . . . . . . . . . . . . . . . . . .
Figure 1–28: Waveform Centered and Adjusted Vertically 1–25. . . . . . . . .
Figure 1–29: Cursor Moved to Desired Position 1–25. . . . . . . . . . . . . . . . .
Figure 1–30: Waveform Viewed in Normal Operation 1–26. . . . . . . . . . . . .
Figure 1–31: Waveform Showing Intermittent Changes 1–27. . . . . . . . . . .
Figure 1–32: Waveform Display with No Outgoing Pulses 1–27. . . . . . . . .
Figure 1–33: A Captured Single Sweep 1–29. . . . . . . . . . . . . . . . . . . . . . . .
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1502C MTDR Service Manual
Table of Contents
Figure 2–1: Start-up Measurement Display 2–2. . . . . . . . . . . . . . . . . . . .
Figure 2–2: Measurement Display with 3-foot Cable 2–2. . . . . . . . . . . .
Figure 2–3: Cursor at End of 3-foot Cable 2–3. . . . . . . . . . . . . . . . . . . . .
Figure 2–4: Flat-Line Display Out to 50,000+ Feet 2–3. . . . . . . . . . . . . .
Figure 2–5: Flat-Line Display at –2.000 ft 2–4. . . . . . . . . . . . . . . . . . . . .
Figure 2–6: Waveform Off the Top of the Display 2–4. . . . . . . . . . . . . . .
Figure 2–7: Waveform at the Bottom of the Display 2–5. . . . . . . . . . . . .
Figure 2–8: Waveform with Gain at 5.00 mr/div 2–5. . . . . . . . . . . . . . .
Figure 2–9: Top of Pulse on Center Graticule 2–7. . . . . . . . . . . . . . . . . .
Figure 2–10: Rising Edge of Incident Pulse in Left-most
Major Division 2–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 2–11: Waveform Centered, Cursor at 0.000 ft 2–8. . . . . . . . . . . . .
Figure 2–12: Pulse Centered on Display 2–8. . . . . . . . . . . . . . . . . . . . . . .
Figure 2–13: Cursor on Lowest Major Graticule that Rising
Edge Crosses 2–9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 2–14: Cursor on Highest Major Graticule that Rising
Edge Crosses 2–9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 2–15: Jitter Apparent on Leading Edge of Incident Pulse 2–10. . . .
Figure 2–16: Jitter Captured Using Max Hold 2–10. . . . . . . . . . . . . . . . . . .
Figure 5–1: System Block Diagram 5–2. . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 5–2: Waveform Accumulation Diagram 5–3. . . . . . . . . . . . . . . . .
Figure 5–3: Power Supply Block Diagram 5–4. . . . . . . . . . . . . . . . . . . . .
Figure 5–4: Processor Block Diagram 5–8. . . . . . . . . . . . . . . . . . . . . . . .
Figure 5–5: Option Port Interface Block Diagram 5–11. . . . . . . . . . . . . . .
Figure 5–6: Video Processor Block Diagram 5–13. . . . . . . . . . . . . . . . . . .
Figure 5–7: Video Processor Output 5–15. . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 5–8: Timebase Block Diagram 5–16. . . . . . . . . . . . . . . . . . . . . . . .
Figure 5–9: Timebase Control 5–17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 5–10: Combined Effects of Time Delay 5–18. . . . . . . . . . . . . . . . . .
Figure 5–11: Calibration of Delay Zero and 50-ns Analog Delay 5–19. . . .
Figure 5–12: Driver/Sampler Block Diagram 5–24. . . . . . . . . . . . . . . . . . .
Figure 5–13: Front Panel Block Diagram 5–26. . . . . . . . . . . . . . . . . . . . . . .
Figure 5–14: Display Module Block Diagram 5–29. . . . . . . . . . . . . . . . . . .
Figure 5–15: SBE Cell 5–30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 5–16: Row Driver Block Diagram 5–31. . . . . . . . . . . . . . . . . . . . . .
Figure 5–17: Column Driver Block Diagram 5–32. . . . . . . . . . . . . . . . . . . .
Figure 5–18: Row Timing Diagram 5–33. . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 5–19: Column Timing Diagram 5–35. . . . . . . . . . . . . . . . . . . . . . . .
1502C MTDR Service Manual
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Table of Contents
Figure 5–20: Shift Register 5–36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 5–21: CPU and Display Memory Interface 5–39. . . . . . . . . . . . . . . .
Figure 6–1: Typical Start-Up Display 6–2. . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–2: Waveform on the Display 6–2. . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–3: Setup Menu 6–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–4: Main Menu 6–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–5: Diagnostics Menu 6–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–6: Front Panel Diagnostic Display 6–5. . . . . . . . . . . . . . . . . . . .
Figure 6–7: Front Panel Diagnostic Display 6–6. . . . . . . . . . . . . . . . . . . .
Figure 6–8: Front Panel Diagnostic Display 6–6. . . . . . . . . . . . . . . . . . . .
Figure 6–9: Front Panel Diagnostic Display 6–7. . . . . . . . . . . . . . . . . . . .
Figure 6–10: Waveform on the Display with No Cable Attached 6–8. . . .
Figure 6–11: Display with 3-ft Cable and Stored Waveform 6–8. . . . . . . .
Figure 6–12: Cursor on Rising Edge of Pulse 6–9. . . . . . . . . . . . . . . . . . .
Figure 6–13: Cursor at 0.000 ft n 6–9. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–14: Cursor on Rising Edge of Pulse 6–9. . . . . . . . . . . . . . . . . . .
Figure 6–15: Flatline Display to >2,000 ft 6–10. . . . . . . . . . . . . . . . . . . . . .
Figure 6–16: Incident Pulse at –2.000 ft 6–11. . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–17: Incident Pulse at –2.000 ft with 3-ft Cable Connected 6–11. .
Figure 6–18: Incident Pulse at –2.000 ft with Max Hold 6–11. . . . . . . . . . .
Figure 6–19: Waveform at Top of the Display 6–12. . . . . . . . . . . . . . . . . .
Figure 6–20: Waveform at Bottom of the Display 6–13. . . . . . . . . . . . . . . .
Figure 6–21: Waveform at Centered 6–13. . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–22: Cursor Moved to 100.000 ft 6–14. . . . . . . . . . . . . . . . . . . . . .
Figure 6–23: Noise with Gain at 5.00 mr 6–14. . . . . . . . . . . . . . . . . . . . . .
Figure 6–24: Noise Diagnostic Display 6–15. . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–25: Service Diagnostic Menu 6–15. . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–26: Sampling Efficiency Diagnostic 6–16. . . . . . . . . . . . . . . . . . .
Figure 6–27: Service Diagnostic Menu 6–16. . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–28: Service Diagnostic Menu 6–17. . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–29: Waveform with Cursor at –2.000 ft 6–18. . . . . . . . . . . . . . . . .
Figure 6–30: Waveform at 50 mr/div 6–18. . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–31: Waveform at 5 mr/div 6–19. . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–32: Incident Pulse at Center of Display 6–19. . . . . . . . . . . . . . . . .
Figure 6–33: Incident Pulse Centered, Vertical Increased 6–20. . . . . . . . . .
Figure 6–34: Cursor on Rising Edge at First Horizontal Graticule 6–20. . .
Figure 6–35: Cursor on Rising Edge at Last Horizontal Graticule 6–21. . .
Figure 6–36: Rising Edge at Center of Display 6–22. . . . . . . . . . . . . . . . . .
vi
1502C MTDR Service Manual
Table of Contents
Figure 6–37: Rising Edge with Scale at 1.0 mr/div 6–22. . . . . . . . . . . . . . .
Figure 6–38: Rising Edge with Max Hold on 6–22. . . . . . . . . . . . . . . . . . . .
Figure 6–39: Head Alignment Chart Print 6–23. . . . . . . . . . . . . . . . . . . . . .
Figure 6–40: Circuit Board Locations in the Instrument 6–25. . . . . . . . . . .
Figure 6–41: Power Supply Board 6–27. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–42: Power Supply Test Points TP1020 and TP1010 6–27. . . . . .
Figure 6–43: Power Supply Test Point TP2030 6–28. . . . . . . . . . . . . . . . .
Figure 6–44: Connector Plug P5040 and Pins J5040 on Bottom of
Main Board 6–29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–45: Power Supply Test Point TP1020 6–29. . . . . . . . . . . . . . . . .
Figure 6–46: Power Supply Test Point TP2030 6–30. . . . . . . . . . . . . . . . .
Figure 6–47: Location of Main Board in Instrument 6–30. . . . . . . . . . . . . .
Figure 6–48: Main Board Probe Points 6–31. . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–49: Waveform on Display 6–31. . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–50: Battery Connections to Power Supply Board 6–32. . . . . . . . .
Figure 6–51: CR2012 on Power Supply Board 6–33. . . . . . . . . . . . . . . . . .
Figure 6–52: Display Showing Power is Battery 6–33. . . . . . . . . . . . . . . . .
Figure 6–53: Display Showing Battery Voltage is Low 6–33. . . . . . . . . . . .
Figure 6–54: R2012 on Power Supply Board 6–34. . . . . . . . . . . . . . . . . . . .
Figure 6–55: Driver/Sampler Board Location 6–35. . . . . . . . . . . . . . . . . . .
Figure 6–56: TP1030 on Driver/Sampler Board 6–35. . . . . . . . . . . . . . . . .
Figure 6–57: R1018 on Front Panel Board 6–36. . . . . . . . . . . . . . . . . . . . . .
Figure 6–58: LCD Pattern with Contrast Too Light 6–36. . . . . . . . . . . . . . .
Figure 6–59: LCD Pattern with Contrast Too Dark 6–37. . . . . . . . . . . . . . .
Figure 6–60: LCD Pattern Adjusted for Sharpness 6–37. . . . . . . . . . . . . . .
Figure 6–61: Waveform with Contrast Too Light 6–38. . . . . . . . . . . . . . . . .
Figure 6–62: Waveform with Contrast Adjusted Correctly 6–38. . . . . . . . .
Figure 6–63: Driver/Sampler Board Location 6–39. . . . . . . . . . . . . . . . . . .
Figure 6–64: Incident Pulse at –2.000 ft 6–40. . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–65: R1042 on Driver/Sampler Board 6–40. . . . . . . . . . . . . . . . . .
1502C MTDR Service Manual
Figure 7–1: Location of Voltage Selector and Fuse Holder on
Rear Panel 7–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 7–2: Power Supply Module and P/O Rear Panel 7–4. . . . . . . . . .
Figure 7–3: Main Board 7–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 7–4: EPROM on Main Board 7–7. . . . . . . . . . . . . . . . . . . . . . . . .
Figure 7–5: Lithium Battery on Main Board 7–8. . . . . . . . . . . . . . . . . . .
Figure 7–6: Display Module/Front Panel Board Screw Locations 7–10. . .
Figure 7–7: Display Module/Front Panel Board Showing Hex Nuts 7–10.
vii
Table of Contents
Figure 7–8: Location of Default Jumper on Front Panel Board 7–11. . . . .
Figure 7–9: Default Jumper Positions 7–11. . . . . . . . . . . . . . . . . . . . . . . .
Figure 7–10: Main Board TP1041 and TP3040 7–16. . . . . . . . . . . . . . . . . .
Figure 7–11: Main Board TP3041 and TP4040 7–16. . . . . . . . . . . . . . . . . .
Figure 7–12: Main Board TP6010 and TP7010 7–16. . . . . . . . . . . . . . . . . .
Figure 7–13: Main Board TP9011 and TP9041 7–17. . . . . . . . . . . . . . . . . .
Figure 7–14: Front Panel CABLE Connector 7–17. . . . . . . . . . . . . . . . . . .
Figure 7–15: Installing the Case Cover Over the Chassis 7–19. . . . . . . . . .
Figure 9–1: Special Schematic Symbols 9–3. . . . . . . . . . . . . . . . . . . . . .
Figure 9–2: Component Locator – Main Board 9–13. . . . . . . . . . . . . . . . .
Schematics – Main Board 9–14. . . . . . . . . . . . . . . . . . . . . . . .
Figure 9–3: Component Locator – Front Panel Board 9–23. . . . . . . . . . . .
Schematics – Front Panel 9–24. . . . . . . . . . . . . . . . . . . . . . . .
Figure 9–4: Component Locator – Power Supply Board 9–26. . . . . . . . . .
Schematics – Power Supply 9–27. . . . . . . . . . . . . . . . . . . . . .
Figure 9–5: Component Locator – Driver/Sampler Board 9–29. . . . . . . . .
Schematics – Driver/Sampler 9–30. . . . . . . . . . . . . . . . . . . . .
Figure 10–1: Cabinet 10–13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 10–2: Frame, Assemblies and Front Panel Controls 10–15. . . . . . . . .
Figure 10–3: Power Supply 10–17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
viii
1502C MTDR Service Manual
List of Tables
Table of Contents
Shipping Carton Test Strength xv. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuse / Voltage Ratings 1–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Vp of Various Dielectric Types 1–11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operator Performance Checks – Equipment Required 2–1. . . . . . . . . . . . . . .
Specifications: Electrical Characteristics 3–1. . . . . . . . . . . . . . . . . . . . . . . . .
Specifications: Environmental Characteristics 3–3. . . . . . . . . . . . . . . . . . . . .
Certifications and Compliances 3–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Specifications: Physical Characteristics 3–5. . . . . . . . . . . . . . . . . . . . . . . . . .
Option Port Wiring Configuration 5–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Row Driver Latch Bits 5–34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Column Driver Latch Bits 5–36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Controller Periods 5–37. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Calibration Performance Check – Equipment Required 6–1. . . . . . . . . . . . . .
Adjustment Procedures – Equipment Required 6–25. . . . . . . . . . . . . . . . . . . .
Main Board Voltages, Tolerances, Test Point Locations 6–28. . . . . . . . . . . . . .
Maintenance – Equipment Required 7–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Cord Conductor Color Code 7–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sealing Materials 7–18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1502C MTDR Service Manual
ix
Table of Contents
x
1502C MTDR 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. To avoid potential hazards, use this
product only as specified.
Only qualified personnel should perform service procedures.
To Avoid Fire or Personal Injury
Power Source
Use Proper Power Cord. Use only the power cord specified for this product and
certified for the country of use.
Use Proper V oltage Setting. Before applying power, ensure that the line selector is
in the proper position for the power source being used.
This product is intended to operate from a power source that will not apply more than
250 volts RMS between the supply conductors or between the supply conductor and
ground. A protective ground connection, by way of the grounding conductor in the
power cord, is essential for safe operation.
Ground the Product. 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.
The standard power cord (161–0288–00) is rated for outdoor use. All other optional
power cords are rated for indoor use only.
Observe All Terminal Ratings. To avoid fire or shock hazard, observe all ratings
and markings on the product. Consult the product manual for further ratings
information before making connections to the product.
Do not apply a potential to any terminal, including the common terminal, that
exceeds the maximum rating of that terminal.
1502C MTDR Service Manual
Replace Batteries Properly. Replace batteries only with the proper type and rating
specified.
Recharge Batteries Properly. Recharge batteries for the recommended charge
cycle only.
Use Proper AC Adapter. Use only the AC adapter specified for this product.
Do Not Operate Without Covers. Do not operate this product with covers or panels
removed.
Use Proper Fuse. Use only the fuse type and rating specified for this product.
Avoid Exposed Circuitry. Do not touch exposed connections and components
when power is present.
xi
General Safety Summary
Do Not Operate With Suspected Failures. If you suspect there is damage to this
product, have it inspected by qualified service personnel.
Do Not Operate in an Explosive Atmosphere.
Symbols and Terms
T erms 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.
CAUTION. Caution statements identify conditions or practices that could result in
damage to this product or other property.
T erms on the Product. 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.
Symbols on the Product. The following symbols may appear on the product:
xii
CAUTION
Refer to Manual
WARNING
High Voltage
Double
Insulated
Protective Ground
(Earth) Terminal
1502C MTDR 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 Care When Servicing
With Power On
Disposal of Batteries
Do not perform internal service or adjustments of this product unless another person
capable of rendering first aid and resuscitation is present.
T o avoid electric shock, disconnect the main power by means of the power cord or
the power switch.
Dangerous voltages or currents may exist in this product. Disconnect power, remove
battery, and disconnect test leads before removing protective panels, soldering, or
replacing components.
To avoid electric shock, do not touch exposed connections.
This instrument contains a lead-acid battery . Some states and/or local jurisdictions
might require special disposition/recycling of this type of material in accordance
with Hazardous Waste guidelines. Check your local and state regulations prior to
disposing of an old battery.
T ektronix Factory Service will accept 1502C batteries for recycling. If you choose
to return the battery to us for recycling, the battery cases must be intact, the battery
should be packed with the battery terminals insulated against possible short-circuits,
and should be packed in shock-absorbant material.
1502C MTDR Service Manual
Tektronix, Inc.
Attn: Service Department
P.O. Box 500
Beaverton, Oregon 97077 U.S.A.
For additional information, phone:1-800-TEK-WIDE
xiii
Service Safety Summary
xiv
1502C MTDR Service Manual
General Information
Product Description
Battery Operation
Options
The Tektronix 1502C Metallic-cable Time-Domain Reflectometer (MTDR) is a
cable test instrument that uses radar principles to determine the electrical
characteristics of metallic cables.
The 1502C generates a half-sine wave signal, applies it to the cable under test, and
detects and processes the reflected voltage waveform. These reflections are
displayed in the 1502C liquid crystal display (LCD), where distance measurements
may be made using a cursor technique. Impedance information may be obtained
through interpreting waveform amplitude.
The waveform may be temporarily stored within the 1502C and recalled or may be
printed using the optional dot matrix strip chart recorder, which installs into the
front-panel Option Port.
The 1502C may be operated from an AC power source or an internal lead-gel
battery, which supplies a minimum of eight hours operating time (see the
Specifications chapter for specifics).
Options available for the 1502C are explained in the Options and Accessories
chapter of this manual.
Standards, Documents,
and References Used
Changes and History
Information
1502C MTDR Service Manual
Terminology used in this manual is in accordance with industry practice.
Abbreviations are in accordance with ANSI Y1.1–19722, with exceptions and
additions explained in parentheses in the text. Graphic symbology is based on ANSI
Y32.2–1975. Logic symbology is based on ANSI Y32.14–1973 and manufacturer’s
data books or sheets. A copy of ANSI standards may be obtained from the Institute
of Electrical and Electronic Engineers, 345 47th Street, New York, NY 10017.
Changes that involve manual corrections and/or additional data will be incorporated
into the text and that page will show a revision date on the inside bottom edge.
History information is included in any diagrams in gray.
xv
General Information
Installation and Repacking
Unpacking and InItial
Inspection
Power Source and Power
Requirements
Before unpacking the 1502C from its shipping container or carton, inspect for signs
of external damage. If the carton is damaged, notify the carrier. The shipping carton
contains the basic instrument and its standard accessories. Refer to the replaceable
parts list in the Service Manual for a complete listing.
If the contents of the shipping container are incomplete, if there is mechanical
damage or defect, or if the instrument does not meet operational check requirements,
contact your local T ektronix Field Office or representative. If the shipping container
is damaged, notify the carrier as well as Tektronix.
The instrument was inspected both mechanically and electrically before shipment.
It should be free if mechanical damage and meet or exceed all electrical
specifications. Procedures to check operational performance are in the Performance
Checks appendix. These checks should satisfy the requirements for most receiving
or incoming inspections.
The 1502C is intended to be operated from a power source that will not apply more
than 250 volts RMS between the supply conductors or between either supply
conductor and ground. A protective ground connection, by way of the grounding
conductor in the power cord, is essential for safe operation.
The AC power connector is a three-way polarized plug with the ground (earth) lead
connected directly to the instrument frame to provide electrical shock protection. If
the unit is connected to any other power source, the unit frame must be connected
to earth ground.
Repacking for Shipment
xvi
Power and voltage requirements are printed on the back panel. The 1502C can be
operated from either 115 VAC or 230 VAC nominal line voltage at 45 Hz to 440 Hz,
or a 12 VDC supply, or an internal battery.
Further information on the 1502C power requirements can be found in the Safety
Summary in this section and in the Operating Instructions chapter.
When the 1502C is to be shipped to a T ektronix Service Center for service or repair,
attach a tag showing the name and address of the owner, name of the individual at
your firm who may be contacted, the complete serial number of the instrument, and
a description of the service required. If the original packaging is unfit for use or is
not available, repackage the instrument as follows:
1. Obtain a carton of corrugated cardboard having inside dimensions that are at
least six inches greater than the equipment dimensions to allow for cushioning.
The test strength of the shipping carton should be 275 pounds (102.5 kg). Refer
to the following table for test strength requirements:
1502C MTDR Service Manual
General Information
SHIPPING CARTON TEST STRENGTH
Gross Weight (lb)
0 – 10 200
11 – 30 275
31 – 120 375
121 – 140 500
141 – 160 600
CAUTION. The battery pack should be removed fr om the instrument before shipping.
If it is necessary to ship the battery, it should be wrapped and secured separately
before being packed with the instrument.
2. Install the front cover on the 1502C and surround the instrument with
polyethylene sheeting to protect the finish.
Carton Test Strength (lb)
3. Cushion the instrument on all sides with packing material or urethane foam
between the carton and the sides of the instrument.
4. Seal with shipping tape or an industrial stapler.
If you have any questions, contact your local Tektronix Field Office or
representative.
1502C MTDR Service Manual
xvii
General Information
Contacting Tektronix
Product
Support
Service
support
Toll-free
Number
Postal
Address
For questions about using Tektronix measurement products, call
toll free in North America:
1-800-833-9200
6:00 a.m. – 5:00 p.m. Pacific time
Or contact us by e-mail:
tm_app_supp@tek.com
For product support outside of North America, contact your local
Tektronix distributor or sales office.
T ektronix offers a range of services, including Extended Warranty
Repair and Calibration services. Contact your local Tektronix
distributor or sales office for details.
For a listing of worldwide service centers, visit our web site.
In North America:
1-800-833-9200
An operator can direct your call.
Tektronix, Inc.
Department or name (if known)
P.O. Box 500
Beaverton, OR 97077
USA
Web site www.tektronix.com
xviii
1502C MTDR Service Manual
Operating Instructions
Overview
Handling
Powering the 1502C
The 1502C front panel is protected by a watertight cover, in which the standard
accessories are stored. Secure the front cover by snapping the side latches outward.
If the instrument is inadvertently left on, installing the front cover will turn off the
POWER switch automatically.
The carrying handle rotates 325° and serves as a stand when positioned beneath the
instrument.
Inside the case, at the back of the instrument, is a moisture-absorbing canister
containing silica gel. In extremely wet environments, it might be be necessary to
periodically remove and dry the canister. This procedure is explained in the 1502C
Service Manual.
The 1502C can be stored in temperatures ranging from –62° C to +85° C. However,
if the temperature is below –40° C or above +55° C, the battery pack should be
removed and stored separately. Battery storage temperature should be –40° C to
+55° C.
In the field, the 1502C can be powered using the internal battery . For AC operation,
check the rear panel for proper voltage setting. The voltage selector can be seen
through the window of the protective cap. If the setting differs from the voltage
available, it can be easily changed. Simply remove the protective cap and select the
proper voltage using a screwdriver.
1502C MTDR Service Manual
REMOVE
CAP TO
SELECT
VOLTAGE
REMOVE
CAP TO
REPLACE
FUSE
Voltage
Selector
Line Fuse
AC Power
Cord Receptacle
Figure 1–1: Rear Panel Voltage Selector, Fuse, AC Receptacle
1–1
Operating Instructions
The 1502C is intended to be operated from a power source that will not apply more
than 250 V RMS between the supply conductors or between either supply conductor
and ground. A protective ground connection by way of the grounding conductor in
the power cord is essential for safe operation.
The AC power connector is a three-way polarized plug with the ground (earth) lead
connected to the instrument frame to provide electrical shock protection. If the unit
is connected to any other power source, the unit frame must be connected to an earth
ground. See Safety and Installation section.
CAUTION. If you change the voltage selector, you must change the line fuse to the
appropriate value as listed near the fuse holder and in the table below.
FUSE RATING VOLTAGE RATING
250 V NOMINAL RANGE
0.3 A T 115 VAC (90 – 132 VAC)
0.15 A T 230 VAC (180 – 250 VAC)
Care of the Battery Pack
Battery Charging
CAUTION. Read these instructions concerning the care of the battery pack. They
contain instructions that reflect on your safety and the performance of the
instrument.
The 1502C can be powered by a rechargeable lead-gel battery pack that is accessible
only by removing the case from the instrument. When AC power is applied, the
battery pack is charged at a rate that is dependent on the battery charge state.
The battery pack will operate the 1502C for a minimum of eight continuous hours
(including making 30 chart recordings) if the LCD backlight is turned off.
The battery pack will charge fully in 16 hours when the instrument is connected, via
the power cord, to an AC power source with the instrument turned off. The
instrument may be turned on and operated while the batteries are charging, but this
will increase the charging time. For longest battery life, a full charge is preferred
over a partial charge.
For maximum capacity , the batteries should be charged within a temperature range
of +20° C to +25° C. However, the batteries can be charged within a temperature
range of 0° C to +40° C and operated in temperatures ranging from –10° C to +55° C.
1–2
1502C MTDR Service Manual
Battery Removal
Operating Instructions
CAUTION. Do not charge battery pack below 0° C or above +40° C. Do not
discharge battery pack below –10° C or above +55° C. If r emoving the battery pack
during or after exposure to these extreme conditions, turn the instrument off and
remove the AC power cord.
The battery pack should be stored within a temperature range of –35° C to +65° C.
However, the self-discharge rate will increase as the temperature increases.
If the instrument is stored with the battery pack installed, the battery pack should
be charged every 90 days. A fully charged battery pack will lose about 12% of its
capacity in three to four months if stored between +20° C and +25° C.
NOTE. The battery pack in the 1502C is inside the instrument case with no external
access. Refer removal and replacement to qualified service personnel.
1. Ensure that the instrument power is off.
2. If the instrument is connected to an AC power source, remove the AC power
cable from the source and from the instrument.
3. If installed, remove the chart recorder, or other device, from the option port.
4. Loosen the four screws on the back of the case and set the instrument face-up
on a flat surface.
5. Swing the handle out of the way of the front panel.
6. Break the chassis seal by pushing downward with both hands on the handle
pivots on each side of the case.
7. Grasp the case with one hand and tilt the chassis out with the other. Lift by
grasping the outside perimeter of the front panel.
CAUTION. Do not lift the instrument by the front-panel controls. The controls will
be damaged if you do so.
8. Remove the top shield from the instrument by gently lifting the rear edge near
the sides of the instrument.
9. Unplug the battery cable positive lead at the battery.
1502C MTDR Service Manual
10. Unplug the battery cable negative lead at the battery.
11. Unplug the battery cable at the power supply.
12. Remove the cable.
1–3
Operating Instructions
13. Remove the two screws mounting the battery clamp to the chassis.
14. Carefully remove the clamp without touching the battery terminals.
15. Lift the battery out.
To re-install or replace the battery, repeat the above steps in reverse order.
Low Battery
If the battery is low, it will be indicated on the LCD (bat/low). If this is the case,
protective circuitry will shut down the 1502C within minutes. Either switch to AC
power or work very fast. If the instrument is equipped with a chart recorder, using
the recorder will further reduce the battery level, or the added load might shut down
the instrument.
bat/low 0.000 ft
O
N
O
F
F
O
F
F
O
F
F
1 avg
500 mr 500 ft
Low Battery
Indicator
Figure 1–2: Display Showing Low Battery Indication
Protection circuits in the charger prevent deep discharge of the batteries during
instrument operation. The circuits automatically shut down the instrument
whenever battery voltage falls below approximately 10 V. If shutdown occurs, the
batteries should be fully recharged before further use.
1–4
Low Temperature
Operation
NOTE. Turn the POWER switch off after instrument shutdown to prevent continued
discharge of the batteries.
Under low AC voltage conditions, AC fuse ratings might be exceeded if the battery
if fully discharged and a chart r ecor ding is being made. Allow the battery to charge
for about one hour before attempting to make a chart recording, or use AC only.
When operating the 1502C in an environment below +10° C, a heater will activate.
The element is built into the LCD module and will heat the display to permit normal
operation. Depending on the surrounding temperature, it might take up to 15
minutes to completely warm the crystals in the LCD. Once warmed, the display will
operate normally.
1502C MTDR Service Manual
Preparing to Use the 1502C
Check the power requirements, remove the front cover, and you are ready to test
cables. The following pages explain the front-panel controls.
Operating Instructions
11
12
10
13
8
7
9
0.2 ft
METALLIC TDR
CABLE TESTER
POSITION
POSITION
Vp
.5
.4
.3
.04
.6
.9
.05
.03
.7
.8
.06
.02
.07
.08
.01
.09
.00
POWER
(PULL ON)
1
MENU
VIEW
INPUT
VIEW
STORE
VIEW
DIFF
STORE
DO NOT APPLY
EXT VOLTAGE
Tektronix
1502B
ac 0.00 ft
O
N
O
F
F
O
F
F
O
F
F
1 avg
NOISE FILTER VERT SCALE DIST/DIV
HORZ
VERT
2
500 mr
SET REF
3 4 5 6
Figure 1–3: 1502C Front-Panel Controls
CAUTION. Do not connect live circuits to the CABLE connector. V oltages exceeding
5 volts can damage the driver or sampler circuits.
Bleed the test cable of any residual static charge before attaching it to the
instrument. To bleed the cable, connect the standard 50W terminator and standar d
female-to-female BNC connector together, then temporarily attach both to the
cable. Remove the connectors before attaching the cable to the instrument.
When testing receiving antenna cables, avoid close proximity to transmitters.
Voltages may appear on the cable if a nearby transmitter is in use, resulting in
damage to the instrument. Before testing, be sure that there are no RF voltages
present, or disconnect the cable at both ends.
1502C MTDR Service Manual
1–5
Operating Instructions
Display
Power
Type CursorWaveform
Front-Panel to Cursor
Distance Window
Front-Panel Controls
NOISE FILTER
HORZ
VERT SET REF
View Input
Indicator
View Store
Indicator
View Difference
Indicator
Store
Indicator
ac
O
N
O
F
F
O
F
F
O
F
F
1 avg
Selected
Noise Filter
500 mr 0.2 ft
Selected Selected
Vertical Scale Distance per
Division
0.000 ft
Figure 1–4: Display and Indicators
1. CABLE: A female BNC connector for attaching a cable to the 1502C for
testing.
2. NOISE FILTER: If the displayed waveform is noisy, the apparent noise can
be reduced by using noise averaging. A veraging settings are between 1 and 128.
The time for averaging is directly proportional to the averaging setting chosen.
A setting of 128 might take the instrument up to 35 seconds to acquire and
display a waveform. The first two positions on the NOISE FILTER control are
used for setting the vertical and horizontal reference points. The selected value
or function is displayed above the control on the LCD.
Grid
1–6
VERT SCALE
DIST/DIV
3. VERT SCALE: This control sets the vertical sensitivity, displayed in mr per
division, or the vertical gain, displayed in dB. Although the instrument defaults
to millirho, you may choose the preferred mode from the Setup Menu. The
selected value is displayed above the control on the LCD.
4. DIST/DIV: Determines the number of feet (or meters) per division across the
display. The minimum setting is 0.1 ft/div (0.025 meters) and the maximum
setting is 200 ft/div (50 meters). The selected value is displayed above the
control on the LCD.
A standard instrument defaults to ft/div. A metric instrument (Option 05)
defaults to m/div, but either may be changed temporarily from the menu. The
default can be changed by changing an internal jumper (see 1502C Service
Manual and always refer such changes to qualified service personnel).
1502C MTDR Service Manual
Operating Instructions
.3
.4 .5
POWER
(PULL ON)
n
o
n
o
Vp
.03
.6
.7
.02
.8
.01
.9 .00
POSITION
POSITION
MENU
.04 .05
5. Vp: The two Velocity of Propagation controls are set according to the
.06
.07
.08
.09
propagation velocity factor of the cable being tested. For example, solid
polyethylene commonly has a Vp of 0.66. Solid polytetraflourethylene (T eflon
) is approximately 0.70. Air is 0.99. The controls are decaded: the left control
is the first digit and the right control is the second digit. For example, with a Vp
of 0.30, the first knob would be set to .3 and the second knob to .00.
6. POWER: Pull for power ON and push in for power OFF . When the front cover
is installed, this switch is automatically pushed OFF.
n
7.
POSITION: This is a continuously rotating control that positions the
o
displayed waveform vertically, up or down the LCD.
n
o
8.
POSITION: This is a continuously rotating control that moves a vertical
cursor completely across the LCD graticule. In addition, the waveform is also
moved when the cursor reaches the extreme right or left side of the display. A
readout (seven digits maximum) is displayed in the upper right corner of the
LCD, showing the distance from the front panel BNC to the current cursor
location.
9. MENU: This pushbutton provides access to the menus and selects items chosen
from the menus.
VIEW
INPUT
VIEW
STORE
VIEW
DIFF
STORE
Menu Selections
Main Menu
10. VIEW INPUT: When pushed momentarily, this button toggles the display of
the waveform acquired at the CABLE connector. This function is useful to stop
displaying a current waveform to avoid confusion when looking at a stored
waveform. This function defaults to ON when the instrument is powered up.
11. VIEW STORE: When pushed momentarily, this button toggles the display of
the stored waveform.
12. VIEW DIFF: When pushed momentarily , this button toggles the display of the
current waveform minus the stored waveform and shows the difference between
them.
13. STORE: When pushed momentarily, the waveform currently displayed will be
stored in the instrument memory . If a waveform is already stored, pushing this
button will erase it. The settings of the stored waveform are available from the
first level menu under View Stored Waveform Settings.
There are several layers of menu, as explained below.
The Main Menu is entered by pushing the MENU button on the front panel.
1. Return to Normal Operations puts the instrument into normal operation
mode.
1502C MTDR Service Manual
1–7
Operating Instructions
2. Help with Instrument Controls explains the operation of each control. When
a control or switch is adjusted or pushed, a brief explanation appears on the
LCD.
3. Cable Information has these choices:
a. Help with Cables gives a brief explanation of cable parameters.
b. V elocity of Propagation V alues displays a table of common dielectrics and
their Vp values. These are nominal values. The manufacturer’s listed
specifications should be used whenever possible.
c. Impedance Values displays impedances of common cables. In some cases,
these values have been rounded off. Manufacturer’s specifications should
be checked for precise values.
d. Finding Unknown Vp Values describes a procedure for finding an
unknown Vp.
4. Setup Menu controls the manner in which the instrument obtains and displays
its test results.
a. Acquisition Control Menu has these choices:
i. Max Hold Is: On/Off. Turn Max Hold on by pushing MENU then
STORE. In this mode, waveforms are accumulated on the display . Max
Hold can be deactivated by pushing STORE or the mode exited by
using the Setup Menu.
ii. Pulse Is: On/Off. Turns the pulse generator off so the 1502C does not
send out pulses.
iii. Single Sweep Is: On/Off. This function is much like a still camera; it
will acquire one waveform and hold it.
b. Ohms-at-Cursor is: On/Off. When activated, the impedance at thee point
of the cursor is displayed beneath the distance window on the display.
c. Vertical Scale Is: dB/mr. This offers you a choice as to how the vertical
gain of the instrument is displayed. You may choose decibels or millirho.
When powered down, the instrument will default to millirho when powered
back up.
d. Distance/Div Is: ft/m. Offers you a choice of how the horizontal scale is
displayed. You may choose from feet per division or meters per division.
When powered up, the instrument will default to feet unless the internal
jumper has been moved to the meters position. Instructions on changing this
default are contained in the 1502C Service Manual.
1–8
e. Light Is: On/Off. This control turns the electroluminescent backlight
behind the LCD on or off.
1502C MTDR Service Manual
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