Lincoln Electric MULTI-SOURCE SVM155-A Service Manual page 29

Section F-1
-TROUBLESHOOTING & REPAIR SECTION-
Troubleshooting & Repair Section.......................................................................................Section F
How to Use Troubleshooting Guide............................................................................................F-2
PC Board Troubleshooting Procedures and Replacement.........................................................F-3
Troubleshooting Guide ................................................................................................................F-4
Test Procedures ..........................................................................................................................F-9
Control Transformer (T2) Test ...............................................................................................F-9
Input Contactor Test ...........................................................................................................F-13
Main Transformer (T1) Voltage Test ....................................................................................F-17
Static SCR Test...................................................................................................................F-21
Active SCR Test ..................................................................................................................F-25
Control Board Test..............................................................................................................F-31
Firing Board Test.................................................................................................................F-35
Multi-Source Meter Accuracy Test .....................................................................................F-39
Normal Open Circuit Voltage Waveform - No Load ...........................................................F-41
Abnormal Open Circuit Voltage Waveform 1 SCR Not Functioning - No Load.................F-42
Typical SCR Gate Voltage Waveform - No Load................................................................F-43
Replacement Procedures..........................................................................................................F-45
Input Contactor Cleaning and/or Replacement .................................................................F-45
Control Board Removal and Replacement.........................................................................F-49
Firing Board Removal and Replacement............................................................................F-51
SCR Bridge/Heat Sink Assembly Removal and Replacement...........................................F-53
Retest After Repair .............................................................................................................F-59
TABLE OF CONTENTS
MULTI-SOURCE
Section F-1