Tektronix 1502B User manual

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Service Manual
1502B
Metallic Time-Domain Reflectometer
070-6267-04
This document applies for firmware version 5.02
and above.
Warning
The servicing instructions are for use by qualified
personnel only. To avoid personal injury, do not
performanyservicingunlessyouarequalifiedtodo
so.RefertotheSafetySummarypriortoperforming
service.
First Printing: June 1996
Revised: February 1998

  
)+0 15:;9<4-5; 4)5<.)+;<9-, *@ $-2;9651? 0): ) :-91)3 5<4*-9 65 ) 7)5-3 15:-9; 69 ;)/ 69 :;)47-, 65 ;0-
+0)::1: $0- .19:; 3-;;-9 15 ;0- :-91)3 5<4*-9 ,-:1/5);-: ;0- +6<5;9@ 6. 4)5<.)+;<9- $0- 3):; .1=- ,1/1;: 6. ;0-
:-91)3 5<4*-9 )9- )::1/5-, :-8<-5;1)33@ )5, )9- <518<- ;6 -)+0 15:;9<4-5; $06:- 4)5<.)+;<9-, 15 ;0-
%51;-, #;);-: 6. 4-91+) 0)=- :1? <518<- ,1/1;: $0- +6<5;9@ 6. 4)5<.)+;<9- 1: 1,-5;1.1-, ): .6336>:
 $-2;9651? 5+ -)=-9;65 9-/65 %#
 $-2;9651? %51;-, 15/,64 ;, 65,65 5/3)5,
 #65@$-2;9651? )7)5
 $-2;9651? 633)5, & --9-5=--5 $0- -;0-93)5,:
5:;9<4-5;: 4)5<.)+;<9-, .69 $-2;9651? *@ -?;-95)3 =-5,69: 6<;:1,- ;0- %51;-, #;);-: )9- )::1/5-, )
;>6A,1/1; )370) +6,- ;6 1,-5;1.@ ;0- +6<5;9@ 6. 4)5<.)+;<9- -/ ! .69 )7)5  .69 652 65/  .69
:9)-3 -;+
$-2;9651? 5+ !  6?  -)=-9;65 9-/65  %#
!915;-, 15 %#
67@91/0; $-2;9651? 5+  33 91/0;: 9-:-9=-, $-2;9651? 796,<+;: )9- +6=-9-, *@ %# )5, .69-1/5
7);-5;: 1::<-, )5, 7-5,15/ $$" ( )5, $ )9- 9-/1:;-9-, ;9),-4)92: 6. $-2;9651? 5+
   
$01: -8<174-5; 0): *--5 ;-:;-, )5, .6<5, ;6 +6473@ >1;0 ;0- 3141;: .69 )
3)::  ,1/1;)3 ,-=1+- 7<9:<)5; ;6 !)9;  6. ;0-  "<3-: $0-:- 3141;: )9-
,-:1/5-, ;6 796=1,- 9-):65)*3- 796;-+;165 )/)15:; 0)94.<3 15;-9.-9-5+- 15 )
+644-9+1)3 -5=19654-5; $01: -8<174-5; /-5-9);-, <:-: )5, +)5 9),1);-
9),16 .9-8<-5+@ -5-9/@ )5, 1. 56; 15:;)33-, )5, <:-, 15 )++69,)5+- >1;0 ;0-
15:;9<+;165: 4)@ +)<:- 0)94.<3 15;-9.-9-5+- ;6 9),16 +644<51+);165: 7A
-9);165 6. ;01: -8<174-5; 15 ) 9-:1,-5;1)3 )9-) 1: 312-3@ ;6 +)<:- 0)94.<3 15;-9.-9A
-5+- 15 >01+0 +):- ;0- <:-9 >133 *- 9-8<19-, ;6 +699-+; ;0- 15;-9.-9-5+- ); 01:
6>5 -?7-5:-
0)5/-: 69 46,1.1+);165 56; -?79-::3@ )7796=-, *@ $-2;9651? +)5 )..-+;
-41::165 +64731)5+- )5, +6<3, =61, ;0- <:-9: )<;0691;@ ;6 67-9);- ;01:
-8<174-5;
$0-  -;)331+ $14-A64)15 "-.3-+;64-;-9 >): ,-:1/5-, )5, 4)5<.)+;<9-, *@
$-2;9651? 5+
 # '13:65 =-
-5, 9-/65  %#
!065- AA

Certificate of the Manufacturer/Importer
Bescheinigung des Herstellers/Importeurs
NOTICE to the user/operator:
e hereby certify that the Tektronix 1502B Metallic TDR complies with the RF
Interference Suppression requirements of Amtsbl.ĆVfg 1046/1984. The German
Postal Service was notified that the equipment is being marketed. The German
Postal Service has the right to reĆtest the series and to verify that it complies.
TEKTRONIX
Hiermit wird bescheinigt, dadas Tektronix 1502B Metallic TDR Übereinstimmung
mit den Bertimmungen der AmtsblattĆVerfügung 1046/1984 funkentstört ist. Der
Deutschen Bundespost wurde das Inverkehrbringen dieses Gerätes angezeigt
und die Bereschtigung zur Überprufung der Serie auf Einhalten der
Bestimmungen eingeraümt.
TEKTRONIX
The German Postal Service requires that this equipment, when used in a test setup,
may only be operated if the requirements of Postal Regulation, Vfg. 1046/1984, Par.
2, Sect. 1.7.1 are complied with.
Dieses Gerät darf in Meaufbauten nur betrieben werden, wenn die
Voraussetzungen des Par. 2, Ziff. 1.7.1 der Vfg. 1046/1984 eingehalten werden.
NOTICE to the user/operator:
The German Postal Service requires that systems assembled by the operator/user
of this instrument must also comply with Postal Regulation, Vfg. 243/1991, Par. 2,
Sect. 1.
HINWEIS für den Benutzer/Betreiber:
Die vom Betreiber zusammengestellte Anlage, innerhalb derer dieses Gerät
eingesetzt wird, muß ebenfalls den Voraussetzungen nach Par. 2, Ziff. 1 der Vfg.
243/1991, genügen.
HINWEIS für den Benutzer/Betriber:

WARRANTY
!               
   "       "      
"  !            
         !    
       "   " !     
!   "          
             
  " !     !  "    
             "    !
         "    
!  "       "  
 "   "  "      "     
    !         
"        "    !
              
                
              
 "    
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
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.

1502B MTDR Service Manual i
Table of Contents
List of Figures iii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
List of Tables viii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General Safety Summary ix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Service Safety Summary xi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General Information xiii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation and Repacking xiv. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating Instructions 1–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Overview 1–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Preparing to Use the 1502B 1–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Display 1–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front-Panel Controls 1–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Menu Selections 1–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Test Preparations 1–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cable Test Procedure 1–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Additional Features (Menu Selected) 1–25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operator Performance Checks 2–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Specifications 3–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical Characteristics 3–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Environmental Characteristics 3–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Physical Characteristics 3–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Options and Accessories 4–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Option 03: Battery Pack 4–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Option 04: YT–1 Chart Recorder 4–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Option 05: Metric Default 4–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Option 07: YT–1S Chart Recorder 4–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Cord Options 4–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Accessories 4–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit Descriptions 5–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Introduction 5–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Supply 5–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Processor System 5–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Option Port Interface 5–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Video Processor 5–13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Timebase 5–15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Elapsed Time Indicator (SN <B020511 only) 5–22. . . . . . . . . . . . . . . . . . . . . . . . . . .
Driver/Sampler 5–23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Panel 5–25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Display Module 5–29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Contents
ii 1502B MTDR Service Manual
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 6–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Aberrations Check 6–17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Risetime Check 6–19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Jitter Check 6–21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Option 03: Battery Pack Check 6–23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Option 04/07: YT-1/YT-1S Chart Recorder Check 6–23. . . . . . . . . . . . . . . . . . . . . . .
Option 05: Metric Default Check 6–23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Adjustment Procedures 6–24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Visual Inspection 6–25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Supply Checks and Adjustments 6–25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Main Board ”12 VDC Check and Adjust 6–29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Impedance Check 6–34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LCD Check and Adjustment 6–35. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Zero Offset Adjust 6–38. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
After Adjustments are Completed 6–40. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance 7–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Introduction 7–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Preventive Maintenance 7–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Part Removal and Replacement 7–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Troubleshooting 7–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Control Panel Installation 7–20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Top and Bottom EMI Shield Installation 7–21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installing the Case Cover Over the Chassis 7–22. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Replaceable Electrical Parts 8–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Diagrams 9–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Replaceable Mechanical Parts 10–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Contents
1502B MTDR Service Manual iii
List of Figures
Figure 1–1: Rear Panel Voltage Selector, Fuse, AC Receptacle 1–1. . . . .
Figure 1–2: Display Showing Low Battery Indication 1–3. . . . . . . . . . . .
Figure 1–3: 1502B Front-Panel Controls 1–4. . . . . . . . . . . . . . . . . . . . . .
Figure 1–4: Display and Indicators 1–5. . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1–5: Vp Set at .30, Cursor Beyond Reflected Pulse
(Set Too Low) 1–11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1–6: Vp Set at .99, Cursor Less Than Reflected Pulse
(Set Too High) 1–11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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 1–12. . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1–9: Short in the Cable 1–13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1–10: Open in the Cable 1–13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1–11: 455-ft Cable 1–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1–12: 455-ft Cable 1–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1–13: Reflection Adjusted to One Division in Height 1–15. . . . . . .
Figure 1–14: Return Loss 1–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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 1–18. . . . . . . . . . . . . . . . . . . .
Figure 1–18: Display of a Stored Waveform 1–18. . . . . . . . . . . . . . . . . . . .
Figure 1–19: Waveform Moved to Top Half of Display 1–19. . . . . . . . . . . .
Figure 1–20: Current Waveform Centered, Stored Waveform Above 1–20.
Figure 1–21: Current Waveform Center, Stored Waveform Above,
Difference Below 1–20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1–22: Waveform of Three-Foot Lead-in Cable 1–21. . . . . . . . . . . . .
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 1–22. . . .
Figure 1–25: Cursor Moved to 0.00 ft 1–23. . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1–26: Incident Pulse at Three Divisions 1–23. . . . . . . . . . . . . . . . . .
Figure 1–27: Waveform of Short 75WCable 1–24. . . . . . . . . . . . . . . . . . . .
Figure 1–28: Waveform Centered and Adjusted Vertically 1–24. . . . . . . . .
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 1–26. . . . . . . . . . .
Figure 1–32: Waveform Display with No Outgoing Pulses 1–27. . . . . . . . .
Figure 1–33: A Captured Single Sweep 1–28. . . . . . . . . . . . . . . . . . . . . . . .

Contents
iv 1502B MTDR Service Manual
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 5–31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 5–16: Row Driver Block Diagram 5–31. . . . . . . . . . . . . . . . . . . . . .
Figure 5–17: Column Driver Block Diagram 5–32. . . . . . . . . . . . . . . . . . . .
Figure 5–18: Row Timing Diagram 5–34. . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 5–19: Column Timing Diagram 5–35. . . . . . . . . . . . . . . . . . . . . . . .

Contents
1502B MTDR Service Manual v
Figure 5–20: Shift Register 5–37. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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 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 mr6–14. . . . . . . . . . . . . . . . . . . . . .
Figure 6–24: Noise Diagnostic Display 6–15. . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–25: Service Diagnostic Menu 6–15. . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–26: Service Diagnostic Menu 6–16. . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–27: Service Diagnostic Menu 6–17. . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–28: Waveform with Cursor at –2.000 ft 6–18. . . . . . . . . . . . . . . . .
Figure 6–29: Waveform at 50 mr/div 6–18. . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–30: Waveform at 5 mr/div 6–19. . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–31: Incident Pulse at Center of Display 6–19. . . . . . . . . . . . . . . . .
Figure 6–32: Incident Pulse Centered, Vertical Increased 6–20. . . . . . . . . .
Figure 6–33: Cursor on Rising Edge at First Horizontal Graticule 6–20. . .
Figure 6–34: Cursor on Rising Edge at Last Horizontal Graticule 6–21. . .
Figure 6–35: Rising Edge at Center of Display 6–22. . . . . . . . . . . . . . . . . .
Figure 6–36: Rising Edge with Scale at 1.0 mr/div 6–22. . . . . . . . . . . . . . .

Contents
vi 1502B MTDR Service Manual
Figure 6–37: Rising Edge with Max Hold on 6–22. . . . . . . . . . . . . . . . . . . .
Figure 6–38: Head Alignment Chart Print 6–23. . . . . . . . . . . . . . . . . . . . . .
Figure 6–39: Circuit Board Locations in the Instrument 6–24. . . . . . . . . . .
Figure 6–40: Power Supply Board 6–26. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–41: Power Supply Test Points TP1020 and TP1010 6–26. . . . . .
Figure 6–42: Power Supply Test Point TP2030 6–27. . . . . . . . . . . . . . . . .
Figure 6–43: Connector Plug P5040 and Pins J5040 on Bottom of
Main Board 6–28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–44: Power Supply Test Point TP1020 6–28. . . . . . . . . . . . . . . . .
Figure 6–45: Power Supply Test Point TP2030 6–29. . . . . . . . . . . . . . . . .
Figure 6–46: Location of Main Board in Instrument 6–29. . . . . . . . . . . . . .
Figure 6–47: Main Board Probe Points 6–30. . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–48: Waveform on Display 6–30. . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–49: Battery Pack Port Jacks on Frame 6–31. . . . . . . . . . . . . . . . . .
Figure 6–50: CR2012 on Power Supply Board 6–31. . . . . . . . . . . . . . . . . .
Figure 6–51: Display Showing Power is Battery 6–32. . . . . . . . . . . . . . . . .
Figure 6–52: Display Showing Battery Voltage is Low 6–32. . . . . . . . . . . .
Figure 6–53: R2012 on Power Supply Board 6–33. . . . . . . . . . . . . . . . . . . .
Figure 6–54: Driver/Sampler Board Location 6–34. . . . . . . . . . . . . . . . . . .
Figure 6–55: TP1030 on Driver/Sampler Board 6–34. . . . . . . . . . . . . . . . .
Figure 6–56: R1018 on Front Panel Board 6–35. . . . . . . . . . . . . . . . . . . . . .
Figure 6–57: LCD Pattern with Contrast Too Light 6–35. . . . . . . . . . . . . . .
Figure 6–58: LCD Pattern with Contrast Too Dark 6–36. . . . . . . . . . . . . . .
Figure 6–59: LCD Pattern Adjusted for Sharpness 6–36. . . . . . . . . . . . . . .
Figure 6–60: Waveform with Contrast Too Light 6–37. . . . . . . . . . . . . . . . .
Figure 6–61: Waveform with Contrast Adjusted Correctly 6–37. . . . . . . . .
Figure 6–62: Driver/Sampler Board Location 6–38. . . . . . . . . . . . . . . . . . .
Figure 6–63: Incident Pulse at –2.000 ft 6–39. . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–64: R1042 on Driver/Sampler Board 6–39. . . . . . . . . . . . . . . . . .
Figure 7–1: Location of Voltage Selector and Fuse Holder on
Rear Panel 7–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 7–2: Desiccant Cartridge on Rear of Chassis 7–4. . . . . . . . . . . . .
Figure 7–3: Power Supply Module and P/O Rear Panel 7–5. . . . . . . . . .
Figure 7–4: DC (Battery) Banana Plugs 7–8. . . . . . . . . . . . . . . . . . . . . . .
Figure 7–5: Main Board 7–9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 7–6: Elapsed Time Indicator on Main Board 7–9. . . . . . . . . . . . .
Figure 7–7: EPROM on Main Board 7–10. . . . . . . . . . . . . . . . . . . . . . . . .
Figure 7–8: Lithium Battery on Main Board 7–10. . . . . . . . . . . . . . . . . . .

Contents
1502B MTDR Service Manual vii
Figure 7–9: Display Module/Front Panel Board Screw Locations 7–12. . .
Figure 7–10: Display Module/Front Panel Board Showing Hex Nuts 7–13.
Figure 7–11: Location of Default Jumper on Front Panel Board 7–13. . . . .
Figure 7–12: Default Jumper Positions 7–14. . . . . . . . . . . . . . . . . . . . . . . .
Figure 7–13: Main Board TP1041 and TP3040 7–15. . . . . . . . . . . . . . . . . .
Figure 7–14: Main Board TP3041 and TP4040 7–15. . . . . . . . . . . . . . . . . .
Figure 7–15: Main Board TP6010 and TP7010 7–16. . . . . . . . . . . . . . . . . .
Figure 7–16: Main Board TP9011 and TP9041 7–16. . . . . . . . . . . . . . . . . .
Figure 7–17: Front Panel CABLE Connector 7–16. . . . . . . . . . . . . . . . . . .
Figure 7–18: Installing Top and Bottom EMI Shields 7–21. . . . . . . . . . . . .
Figure 7–19: Installing the Case Cover Over the Chassis 7–22. . . . . . . . . .
Figure 9–1: Special Schematic Symbols 9–3. . . . . . . . . . . . . . . . . . . . . .
Figure 9–2: Component Locator – Main Board 9–15. . . . . . . . . . . . . . . . .
Schematics – Main Board 9–16-24. . . . . . . . . . . . . . . . . . . . . .
Figure 9–3: Component Locator – Front Panel Board 9–25. . . . . . . . . . . .
Schematics – Front Panel 9–26-27. . . . . . . . . . . . . . . . . . . . . .
Figure 9–4: Component Locator – Power Supply Board 9–28. . . . . . . . . .
Schematics – Power Supply 9–29. . . . . . . . . . . . . . . . . . . . . .
Figure 9–5: Component Locator – Driver/Sampler Board 9–30. . . . . . . . .
Schematics – Driver/Sampler 9–31. . . . . . . . . . . . . . . . . . .
Schematics – Power Fuse Jack 9–32. . . . . . . . . . . . . . . . . . . .
Figure 10–1: Cabinet 10–17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 10–2: Frame, Assemblies and Front Panel Controls 10–18. . . . . . . . .
Figure 10–3: Power Supply 10–19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 10–4: Battery Pack 10–20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Contents
viii 1502B MTDR Service Manual
List of Tables
Shipping Carton Test Strength xv. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuse / Voltage Ratings 1–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Vp of Various Dielectric Types 1–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operator Performance Checks – Equipment Required 2–1. . . . . . . . . . . . . . .
Specifications: Electrical Characteristics 3–1. . . . . . . . . . . . . . . . . . . . . . . . .
Specifications: Environmental Characteristics 3–3. . . . . . . . . . . . . . . . . . . . .
Specifications: Physical Characteristics 3–4. . . . . . . . . . . . . . . . . . . . . . . . . .
Option Port Wiring Configuration 5–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Row Driver Latch Bits 5–33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Column Driver Latch Bits 5–36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Controller Periods 5–37. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Calibration Performance Check – Equipment Required 6–1. . . . . . . . . . . . . .
Adjustment Procedures – Equipment Required 6–24. . . . . . . . . . . . . . . . . . . .
Main Board Voltages, Tolerances, Test Point Locations 6–27. . . . . . . . . . . . . .
Maintenance – Equipment Required 7–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Cord Conductor Color Code 7–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sealing Materials 7–20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1502B MTDR Service Manual ix
General Safety Summary
The safety information in this summary is for operating personnel. Specific
warnings and cautions will be found throughout the manual where they apply, but
might not appear in this summary. For specific service safety information, see page
xiii.
Terms 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.
Terms 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 in the Manual:
WARNINGor CAUTION
Information
Symbols on the Product:
DANGER
High Voltage ProtectiveGround (Earth)Terminal ATTENTION Referto
Manual
Double
Insulated
Thisproductisintendedtooperatefromapowersourcethatwillnotapplymorethan
250voltsRMSbetweenthesupplyconductorsor between the supply conductor and
Safety Terms and Symbols
Power Source

General Safety Summary
x1502B MTDR Service Manual
ground. A protective ground connection, by way of the grounding conductor in the
power cord, is essential for safe operation.
This product is grounded through the grounding conductor of the power cord. To
avoid electrical shock, plug the power cord into a properly wired receptacle before
connectingto the product input oroutputterminals.A protective ground connection
by way of the grounding conductor in the power cord is essential for safe operation.
Upon loss of the protective-ground connection, all accessible conductive parts
(including knobs and controls that appear to be insulating) can render an electric
shock.
Use only the power cord and connector specified for this product. Do not use this
instrument without a rated AC line cord.
Thestandardpowercord(161–0288–00)isratedforoutdooruse. Allotheroptional
power cords are rated for indoor use only.
Use only a power cord that is in good condition.
Refer cord and connector changes to qualified service personnel.
To avoid fire hazard, use only a fuse of the correct type.
Refer fuse replacement to qualified service personnel.
To avoid explosion, do not operate this product in an explosive atmosphere unless
it has been specifically certified for such operation.
To avoidpersonalinjury, donotremovetheproductcoversorpanels.Donotoperate
the product without the covers and panels properly installed.
Grounding the Product
Danger Arising from Loss
of Ground
Use the Proper Power
Cord
Use the Proper Fuse
Do Not Operate in
Explosive Atmosphere
Do Not Remove Covers or
Panels

1502B MTDR Service Manual xi
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.
Donot perform internal service oradjustmentsofthisproductunlessanother 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
the power switch.
Dangerousvoltagesorcurrentsmayexistinthisproduct.Disconnectpower,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 NiCad battery pack. 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 pack.
Tektronix Factory Service will accept 1502B batteries for recycling. If you choose
to return the battery to us for recycling, the battery cases must be intact, the battery
shouldbepackedwiththebatteryterminalsinsulatedagainstpossibleshort-circuits,
and should be packed in shock-absorbant material.
Send batteries, post-paid, to:
Tektronix, Inc.
Attn: Bend Service
100 S.E. Wilson Ave.
Bend, OR 97702
For additional information, phone: [phone].
Do Not Service Alone
Disconnect Power
Use Care When Servicing
With Power On
Disposal of Batteries

Service Safety Summary
xii 1502B MTDR Service Manual

1502B MTDR Service Manual xiii
General Information
The Tektronix 1502B Metallic-cable Time-Domain Reflectometer (MTDR) is a
cable test instrument that uses radar principles to determine the electrical
characteristics of metallic cables.
The 1502B 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 1502B 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 1502B and recalled or may be
printed using the optional dot matrix strip chart recorder, which installs into the
front-panel Option Port.
The 1502B may be operated from an AC power source or a battery pack consisting
of nine NiCad C-cells, which supply a minimum of five hours operating time (see
the Specifications chapter for specifics).
Options available for the 1502B are explained in the Options and Accessories
chapter of this manual.
Terminology used in this manual is in accordance with industry practice.
Abbreviations are in accordance with ANSI Y1.1–19722, with exceptions and
additionsexplainedinparenthesesinthetext.GraphicsymbologyisbasedonANSI
Y32.2–1975.Logic symbology is based onANSIY32.14–1973andmanufacturer’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.
Changesthatinvolvemanualcorrections and/oradditionaldata willbeincorporated
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.
Product Description
Battery Pack
Options
Standards, Documents,
and References Used
Changes and History
Information

General Information
xiv 1502B MTDR Service Manual
Installation and Repacking
Before unpacking the 1502B 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
damageordefect,oriftheinstrumentdoesnotmeetoperationalcheckrequirements,
contactyourlocal Tektronix Field Officeor 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.Procedurestocheckoperational performance are in the Performance
Checks appendix. These checks should satisfy the requirements for most receiving
or incoming inspections.
The 1502B 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.
Power and voltage requirements are printed on the back panel. The 1502B 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 a battery pack.
Further information on the 1502B power requirements can be found in the Safety
Summary in this section and in the Operating Instructions chapter.
When the 1502B is to be shipped to a Tektronix 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:
Unpacking and InItial
Inspection
Power Source and Power
Requirements
Repacking for Shipment

General Information
1502B MTDR Service Manual xv
SHIPPING CARTON TEST STRENGTH
Gross Weight (lb) Carton Test Strength (lb)
0 – 10 200
11 – 30 275
31 – 120 375
121 – 140 500
141 – 160 600
CAUTION.TheOption03batterypackshouldberemovedfromtheinstrumentbefore
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 1502B and surround the instrument with
polyethylene sheeting to protect the finish.
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.