Lincoln Electric SVM100-A service manual Stick Welding Problems

Page 56

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F-15

TROUBLESHOOTING & REPAIR

 

 

TROUBLESHOOTING GUIDE

 

Observe Safety Guidelines

 

 

 

 

 

 

 

 

detailed in the beginning of this manual.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PROBLEMS

 

POSSIBLE AREAS OF

RECOMMENDED

 

(SYMPTOMS)

 

 

 

MISADJUSTMENT(S)

 

 

COURSE OF ACTION

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

STICK WELDING PROBLEMS

 

 

 

 

 

 

 

Stick electrode “Blasts Off” when

 

 

1. Weld current is set too high

 

 

1.

Possible faulty SCR bridge.

 

 

arc is struck.

 

 

 

for recommended electrode

 

 

 

See Static and Active SCR

 

 

 

 

 

 

size. Reduce preset current

 

 

 

Tests.

 

 

 

 

 

 

adjustment.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2.

Control board may be faulty.

 

 

 

 

 

 

 

 

 

 

Replace.

 

 

 

 

 

 

 

 

 

 

 

Cannot adjust AC Wave Balance

 

 

1. This is a normal condition.

 

 

None

 

 

when welding in the Stick Mode.

 

 

Wave balance keys are

 

 

 

 

 

 

 

 

 

 

 

automatically disabled in the

 

 

 

 

 

 

 

 

 

 

 

Stick Mode.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Machine welds at a very low output

 

 

1. If welding in the Remote

 

 

1.

Check the SCR bridge. See

 

 

regardless of the preset current set-

 

 

Control Mode, the remote

 

 

 

Static and Active SCR Tests.

 

 

ting - arc is stable.

 

 

 

amptrol may be defective or

 

 

 

 

 

 

 

 

 

 

 

not installed properly.

 

 

2.

Check polarity switch (S2)

 

 

 

 

 

 

2. If the output is low when the

 

 

 

connections and operation.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

machine is in the Local

 

 

3.

Check the control transformer

 

 

 

 

 

 

Control Mode, the problem

 

 

 

(T2). See Control Transformer

 

 

 

 

 

 

could be internal to the

 

 

 

Voltage Test.

 

 

 

 

 

 

machine.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4.

The Control board may be

 

 

 

 

 

 

 

 

 

 

faulty. Replace.

 

 

 

 

 

 

 

 

 

 

 

 

Variable or sluggish welding arc

 

 

1. Check work and electrode

 

 

1.

Check polarity switch (S2) for

 

 

when welding in the Stick Mode.

 

 

cables for loose or poor

 

 

 

wear or loose connentions.

 

 

 

 

 

 

connections.

 

 

 

 

 

 

 

 

 

 

 

2. The weld cables may be too

 

 

2.

Check interior connections of

 

 

 

 

 

 

 

 

 

the heavy current carrying

 

 

 

 

 

 

small or too long to permit the

 

 

 

leads.

 

 

 

 

 

 

desired current to flow.

 

 

 

 

 

 

 

 

 

 

 

3. The preset current adjustment

 

 

 

 

 

 

 

 

 

 

 

may be set too low.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact the Lincoln Electric Service Department for technical troubleshooting assistance before you proceed call 216-383-2531 or 1-800-833-9353.

SQUARE WAVE TIG 255

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Contents Square Wave TIG Safety Electric Shock can killARC Rays can burn Fumes and Gases can be dangerousCylinder may explode if damaged Welding Sparks can cause fire or explosionElectric and Magnetic Fields May be dangerousPrécautions DE Sûreté Sûreté Pour Soudage a L’ArcMaster Table of Contents for ALL Sections Table of Contents Installation SectionInstallation Technical Specifications Square Wave TIGSafety Precautions High Frequency Interference ProtectionSelect Suitable Location StackingInput Supply Connections Input ConnectionsGround Connection TIG Torch Connection Reconnect ProcedureOutput Connections Table A.1 Stick Electrode Cable ConnectionOperation Section Operation Operating InstructionsGeneral Warnings Fumes and GasesSection TOC Polarity Do not Switch AC & DC Recti Fier Power Source While Weld ING TIG Gtaw Single PhaseWork Connec Coolant Tion OutputDesign Features Advantages Operational Features and ControlsGeneral Description Recommended Processes and EquipmentWelding Capability LimitationsControls and Settings Control Panel KeysCase Front Controls LoadAccessory Operation TIG Welding Table B.1 Recommended Polarity Settings for TIG WeldingHand and Foot Amptrol Welding Operation TIG Welding GuidelinesSquare 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 Auxiliary Power Advanced TIG Welding FeaturesALL Machines AC Wave Balance and Auto BalanceOverload Protection Square Wave TIG Accessories Section Accessories Options / AccessoriesInstallation of Field Installed Options Undercarriage FunctionMaintenance Section Maintenance MaintenanceRoutine and Periodic Maintenance Safety PrecautionsFigure D.1 General Assembly Exploded View Square Wave TIG Power Supply Block Logic Diagram Theory of Operation SectionTheory of Operation Input Line Voltage and Main TransformerOutput Rectification and Feedback Control High Voltage / High Frequency Circuit DC Welding Output DC Welding CircuitAC Welding Output AC Welding CircuitSCR Operation SCR Operation Square Wave TIGThermal Protection Troubleshooting & Repair Section 1TROUBLESHOOTING & Repair HOW to USE Troubleshooting GuideTroubleshooting & Repair PC Board Troubleshooting ProceduresTroubleshooting Guide Output Problems12/95 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 PC Board Connector Locations Figure F.1 Control Board ConnectorsMaterials Needed Control Transformer T2 Voltage TestTest Description Test Procedure Control BOXControl Transformer T2 Voltage Test Figure F.4 Control Board and TransformerPROTECTION/SNUBBER Board Continuity Test PROTECTION/SNUBBER Board Continuity Test Figure F.6 PROTECTION/SNUBBER Board Test Points Table F.6 Square Wave TIGARC Start Trigger Circuit Test ARC Start Trigger Circuit Test Figure F.9 PROTECTION/SNUBBER Board Test Points Static SCR Test Static SCR Test Figure F.11 Protection Board Plug LocationsActive SCR Test Active SCR Test Figure F.13 PROTECTION/SNUBBER Board Plug LocationsBattery Test Silicon Controlled Rectifier TestNormal Open Circuit Voltage Waveform DC Stick Mode Scope SettingsNormal Open Circuit Voltage Waveform AC Stick Mode Normal Open Circuit Voltage Waveform DC TIG Mode Normal Open Circuit Voltage Waveform AC TIG Mode Typical Output Voltage Waveform Machine Loaded DC TIG Mode Machine Loaded to 200 Amps AT 50 VDCMachine Loaded to 200 Amps AT 46 VAC AC TIG Mode Auto Balance onMachine Loaded to 50 Amps AT 26VAC Volts 5ms Typical SCR Gate Voltage WaveformVolts 2ms Troubleshooting & Repair FAN Motor and Blade Removal Tools RequiredFAN Motor and Blade Removal SCR Heat Sink Assembly Removal Materials RequiredSCR Heat Sink Assembly Removal Recommended Meters for Machine Output Tests Retest After RepairInput Idle Amps Retest After Repair cont’d Figure F.16 Transformer Lead Test PointsElectrical Diagrams Electrical Diagrams Control Board G2150 PTC1,PTC2 THERMISTOR-PTC,56 OHMS,90MAControl Board G2150 cont’d Square Wave TIG PROTECTION/SNUBBER Board L9255 CAPACITOR-CEMO,4700P,50V,10% Square Wave TIG Wiring Diagram Square Wave TIG Machine Schematic Square Wave TIG 6 a 0 a 7 a 8 a 3 CG2150 A C C TControl Board Schematic Square Wave TIG 255 cont’d G2150 Y P a DPROTECTION/SNUBBER Board Schematic Square Wave TIG 255 L9255 Keypad LED Board Square Wave TIG 255 L9212