Square Wave Tig - Lincoln Electric SQUARE WAVE TIG 255 SVM100-A Service Manual

- TROUBLESHOOTING & REPAIR SECTION -
Troubleshooting & Repair Section ................................................................Section F
Safety Precautions.................................................................................................F-1
How to Use Troubleshooting Guide .......................................................................F-1
PC Board Troubleshooting Procedures .................................................................F-2
Troubleshooting Guide ................................................................................F-3 - F-15
PC Board Connector Locations ...........................................................................F-16
Test Procedures
Control Transformer Voltage Test .................................................................F-17
Protection/Snubber Board Continuity Test ....................................................F-20
Arc Start Trigger Circuit Test .........................................................................F-23
Static SCR Test .............................................................................................F-26
Active SCR Test ............................................................................................F-28
Oscilloscope Waveforms
Normal Open Circuit Voltage Waveform DC Stick Mode...............................F-31
Normal Open Circuit Voltage Waveform AC Stick Mode...............................F-32
Normal Open Circuit Voltage Waveform DC TIG Mode ................................F-33
Normal Open Circuit Voltage Waveform AC TIG Mode.................................F-34
Typical Output Voltage Waveform Machine Loaded DC TIG Mode ..............F-35
Typical Output Voltage Waveforms Machine Loaded AC TIG Mode.............F-36
Typical SCR Gate Voltage Waveform ...........................................................F-37
Abnormal Open Circuit Voltage Waveform DC Stick Mode...........................F-38
Abnormal Open Circuit Voltage Waveform AC Stick Mode ...........................F-39
Replacement Procedures
Fan Motor and Blade Removal ......................................................................F-40
SCR Heatsink Assembly Removal ................................................................F-42
Retest After Repair ..............................................................................................F-44
TABLE OF CONTENTS
Section F

SQUARE WAVE TIG 255