Pc Board Troubleshooting Procedures - Lincoln Electric WIRE-MATIC 255 SVM 119-A Service Manual

- TROUBLESHOOTING & REPAIR SECTION -
TROUBLESHOOTING & REPAIR SECTION ........................................................................ Section F
How to use Troubleshooting Guide ....................................................................................................F-1
PC Board Troubleshooting Procedures..............................................................................................F-2
Troubleshooting Guide .......................................................................................................................F-3
Test Procedures
Main Transformer Test................................................................................................................F-10
Static SCR Rectifier Bridge Test.................................................................................................F-13
Active SCR Rectifier Assembly Test ...........................................................................................F-16
Wire Drive Motor and Tachometer Feedback Test .....................................................................F-19
Oscilloscope Waveforms ..................................................................................................................F-22
Normal Open Circuit Voltage Waveform ....................................................................................F-22
Typical Output Voltage Waveform - Machine Loaded ................................................................F-23
Abnormal Output Voltage Waveform - Machine Loaded One Output SCR Not Functioning .....F-24
Abnormal Open Circuit Voltage Output Capacitor Bank Not Functioning ..................................F-25
Typical SCR Gate Voltage Waveform ........................................................................................F-26
Replacement Procedures
Control PC Board Removal and Replacement...........................................................................F-27
Wire Drive Assembly Removal and Replacement......................................................................F-29
SCR Output Rectifier Removal and Replacement .....................................................................F-31
Capacitor Bank Removal and Replacement ..............................................................................F-33
Main Transformer Removal and Replacement...........................................................................F-35
Fan Motor and Fan Removal and Replacement ........................................................................F-37
Retest After Repair .....................................................................................................................F-40
TROUBLESHOOTING & REPAIR
TABLE OF CONTENTS
WIRE-MATIC 255