Table of Contents | Lincoln Electric SVM100-A instruction

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TABLE OF CONTENTS	Section F
- 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

SQUARE WAVE TIG 255

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Lincoln Electric SVM100-A service manual Table of Contents, Troubleshooting & Repair Section

Contents

Square Wave TIG Electric Shock can kill SafetyARC Rays can burn Fumes and Gases can be dangerous Welding Sparks can cause fire or explosion Cylinder may explode if damaged May be dangerous Electric and Magnetic Fields Sûreté Pour Soudage a L’Arc Précautions DE Sûreté Master Table of Contents for ALL Sections Installation Section Table of Contents Technical Specifications Square Wave TIG Installation High Frequency Interference Protection Safety PrecautionsSelect Suitable Location Stacking Input Supply Connections Input ConnectionsGround Connection TIG Torch Connection Reconnect ProcedureOutput Connections Stick Electrode Cable Connection Table A.1 Operation Section Operating Instructions OperationGeneral Warnings Fumes and Gases Section TOC While Weld ING TIG Gtaw Single Phase Polarity Do not Switch AC & DC Recti Fier Power SourceWork Connec Coolant Tion Output Operational Features and Controls Design Features AdvantagesGeneral Description Recommended Processes and Equipment Limitations Welding Capability Control Panel Keys Controls and Settings Load Case Front Controls Table B.1 Recommended Polarity Settings for TIG Welding Accessory Operation TIG WeldingHand and Foot Amptrol Welding Operation TIG Welding Guidelines Square Wave TIG 255 12/95 TIG Welding Sequence Operation 2-STEP ModeTable B.2 Typical Current Ranges 1 for Tungsten Electrodes TIG Welding Sequence Operation 4-STEP Mode Advanced TIG Welding Features Auxiliary PowerALL Machines AC Wave Balance and Auto Balance Overload Protection Square Wave TIG Accessories Section Options / Accessories AccessoriesInstallation of Field Installed Options Undercarriage Function Maintenance Section Maintenance MaintenanceRoutine and Periodic Maintenance Safety Precautions Figure D.1 General Assembly Exploded View Square Wave TIG Theory of Operation Section Power Supply Block Logic Diagram Input Line Voltage and Main Transformer Theory of Operation Output Rectification and Feedback Control High Voltage / High Frequency Circuit DC Welding Circuit DC Welding Output AC Welding Circuit AC Welding Output SCR Operation Square Wave TIG SCR Operation Thermal Protection Troubleshooting & Repair Section HOW to USE Troubleshooting Guide 1TROUBLESHOOTING & Repair PC Board Troubleshooting Procedures Troubleshooting & Repair Output Problems Troubleshooting Guide 12/95 Square Wave TIG Troubleshooting & Repair Recommended Course of Action Problems SymptomsPossible Areas of Misadjustments Function Problems Troubleshooting Guide Troubleshooting & Repair TIG Mode Problems Troubleshooting & Repair Troubleshooting Guide TIG Welding Problems Troubleshooting & Repair Stick Welding Problems Figure F.1 Control Board Connectors PC Board Connector Locations Materials Needed Control Transformer T2 Voltage TestTest Description Control BOX Test Procedure Figure F.4 Control Board and Transformer Control Transformer T2 Voltage Test PROTECTION/SNUBBER Board Continuity Test PROTECTION/SNUBBER Board Continuity Test Table F.6 Square Wave TIG Figure F.6 PROTECTION/SNUBBER Board Test Points ARC Start Trigger Circuit Test ARC Start Trigger Circuit Test Figure F.9 PROTECTION/SNUBBER Board Test Points Static SCR Test Figure F.11 Protection Board Plug Locations Static SCR Test Active SCR Test Figure F.13 PROTECTION/SNUBBER Board Plug Locations Active SCR Test Silicon Controlled Rectifier Test Battery Test Scope Settings Normal Open Circuit Voltage Waveform DC Stick Mode Normal Open Circuit Voltage Waveform AC Stick Mode Normal Open Circuit Voltage Waveform DC TIG Mode Normal Open Circuit Voltage Waveform AC TIG Mode Machine Loaded to 200 Amps AT 50 VDC Typical Output Voltage Waveform Machine Loaded DC TIG Mode Machine Loaded to 200 Amps AT 46 VAC AC TIG Mode Auto Balance onMachine Loaded to 50 Amps AT 26VAC Typical SCR Gate Voltage Waveform Volts 5ms Volts 2ms Troubleshooting & Repair Tools Required FAN Motor and Blade Removal FAN Motor and Blade Removal Materials Required SCR Heat Sink Assembly Removal SCR Heat Sink Assembly Removal Recommended Meters for Machine Output Tests Retest After RepairInput Idle Amps Figure F.16 Transformer Lead Test Points Retest After Repair cont’d Electrical Diagrams Electrical Diagrams PTC1,PTC2 THERMISTOR-PTC,56 OHMS,90MA Control Board G2150 Control Board G2150 cont’d Square Wave TIG PROTECTION/SNUBBER Board L9255 CAPACITOR-CEMO,4700P,50V,10% Square Wave TIG Wiring Diagram Square Wave TIG 6 a 0 a 7 a 8 a 3 C Machine Schematic Square Wave TIG A C C T G2150 Y P a D Control Board Schematic Square Wave TIG 255 cont’d G2150 PROTECTION/SNUBBER Board Schematic Square Wave TIG 255 L9255 Keypad LED Board Square Wave TIG 255 L9212