Lincoln Electric V250-S service manual Routine Maintenance, Filter Capacitor Conditioning

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D-3

MAINTENANCE

D-3

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ROUTINE MAINTENANCE

1.Perform the following preventive maintenance procedures at least once every six months. It is good practice to keep a preventive maintenance record; a record tag attached to the machine works best.

2.Remove the machine wrap-around cover and per- form the input filter capacitor discharge procedure (detail at the beginning of this chapter).

3.Keeping the machine clean will result in cooler operation and higher reliability. Be sure to clean the following areas with a low pressure air stream. See figure D.2 for component locations.

Power and control printed circuit boards

Power switch

Main transformer

Input rectifier

Heat sink fins

Input Filter Capacitors

Output Terminals

4.Examine capacitors for leakage or oozing. Replace if needed.

5.Examine the sheet metal case for dents or break- age. Repair the case as required. Keep the case in good condition to ensure that high voltage parts are protected and correct spacings are maintained. All external sheet metal screws must be in place to assure case strength and electrical ground continuity.

6.Check electrical ground continuity. Using an ohm- meter, measure resistance between either output terminal and an unpainted surface of the machine case. (See Figure D.2 for locations.) Meter reading should be 500,000 ohms or more. If meter reading is less than 500,000 ohms, check for electrical components that are not properly insulated from the case. Correct insulation if needed.

FILTER CAPACITOR

CONDITIONING

A protection circuit is included to monitor the voltage across filter capacitors C1 and C2. In the event that the capacitor voltage is too high, the protection circuit will prevent output. Nominal trip setting is at 230/460 VAC +15%. Reset occurs about 3% lower (230/460 VAC +12%).

On new installations, the protection circuit may also prevent output providing all these circumstances are met:

1.Machine is connected for 380-415 or 440-460 VAC input.

2.Machine did not have power applied for many months.

3.Machine will not produce output when power is first switched on.

If these circumstances apply, the proper action is to switch the machine on and let it idle for up to 30 min- utes. This is required to condition the filter capacitors after an extended storage time. The protection circuit will automatically reset once the capacitor conditioning and resultant voltage levels are acceptable. It may be necessary to turn the power switch off and back on again after this period.

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7. Replace machine cover and screws.

INVERTEC V250-S

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Contents Invertec V250-S Safety Fumes and Gases can be dangerous Electric Shock can killARC Rays can burn Welding Sparks can cause fire or explosion Cylinder may explode if damagedSûreté Pour Soudage a L’Arc Précautions DE SûretéMaster Table of Contents for ALL Sections Table of Contents Installation Section InstallationThree Phase Technical Specifications Invertec V250-SThree Phase Single Phase Select Suitable Location Safety PrecautionsInput Connections Power Input Connection for 50/60 HZ Machines Input Voltage Reconnect ProcedureInput Fuse and Supply Wire Output Cables Remote Control ReceptacleOutput Connections Quick Disconnect PlugsInvertec V250-S Operation Gouging Sparks Safety InstructionsFigure B.1 Case Front Controls Controls and SettingsTIG Welding Constant Current ProcessesManual ARC Welding Stick AIR Carbon ARC CuttingThermal Protection Parallel OperationOverload Protection Invertec V250-S Table of Contents Accessories Section AccessoriesCable Plugs Options / AccessoriesRemote Controls Table of Contents Maintenance Section MaintenanceFigure D.1 Location of Input Filter Capacitor Terminals Input Filter Capacitor Discharge ProcedureFilter Capacitor Conditioning Routine MaintenanceFigure D.2 Location of Maintenance Components Theory of Operation Table of Contents Theory of Operation SectionInput Line Voltage General DescriptionFigure E.2 Protection and PRE-CHARGE Circuits Precharge and ProtectionFigure E.3 Main Transformer Main TransformerFigure E.4 Output Rectification and Control Output Rectification ControlOverload Protection Protection CircuitsInsulated Gate Bipolar Transistor Igbt Operation Maximum Output Pulse Width ModulationMinimum Output Troubleshooting & Repair Oscilloscope Warning HOW to USE Troubleshooting GuideBoard can be dam- aged by static electricity PC Board Troubleshooting ProceduresCourse of Action Possible Areas Recommended SymptomsPerform the Control Board Voltage Checks Possible AreasCapacitor Balance Test Troubleshooting & Repair Perform the Output Diode Test Welding Problems Invertec V250-S Materials Needed Auxiliary Transformer TestTest Description Auxiliary Transformer Test Test ProcedureTable F.1 Auxiliary Transformer Test Points Auxiliary Transformer TestInvertec V250-S Input Rectifier Test Input Rectifier Test Test ProcedureTest Point Terminals Analog Meter X10 Range Table F.2 Input Rectifier Test PointsInvertec V250-S Power Board Resistance Test Test Description Power Board Resistance TestTable F.3 Power Board Resistance Test Points Power Board Resistance TestInvertec V250-S Output Diodes Test Figure F.4 Machine Output Terminals Output Diodes TestInvertec V250-S Diode Modules Power Board Voltage Test Figure F.8 Plug J6 on Power Board Power Board Voltage TestTest Conditions Table F.4. Power Board Voltage Test PointsAcceptable Test Description Invertec V250-S Control Board Voltage Test Figure F.9 Plugs J1-J5 on Control Board Control Board Voltage Test18VAC Table F.5. Control Board Voltage Test PointsInvertec V250-S Protection Circuit Test Figure F.10 Control Board Plug J2 Test Points Protection Circuit TestProtection Circuit Simplified Invertec V250-S Capacitor Balance Test Capacitor Balance Test Figure F.12 Power Board and Capacitor Test LocationsTable F.6 Capacitor Voltages Invertec V250-S Control Board Removal and Replacement V250S Control Control Board Removal and ReplacementProcedure Power Board Removal and Replacement Figure F.14 Power Board Lead Locations Power Board Removal and ReplacementPower Board Replacement Procedure Invertec V250-S Matched Parts Filter Capacitor Removal and ReplacementFigure F.15 Heatsink/Power Board Removal Filter Capacitor Removal and ReplacementPerform Power Board Replacement Procedure in this section Invertec V250-S Input Rectifier Bridge Removal and Replacement Figure F.16 Input Rectifier Lead Locations Input Rectifier Bridge Removal and ReplacementTroubleshooting & Repair Invertec V250-S Materials Needed Snubber Resistors Locking Tabs Invertec V250-S Wrench Allen type wrench Torque wrench Mounting Bolts Diode Modules Bolted Connections Troubleshooting & Repair Invertec V250-S Main Transformer Removal and Replacement Machine Codes below T3 Current Transformer Main Transformer Main Transformer Secondary Leads Figure F.22 Main Transformer Mountings Clear all leads and secure for case wrap-around assembly Invertec V250-S Main Transformer Removal and Replacement Machine Codes Above Figure F.23 Main Transformer Right Side Figure F.24 Main Transformer Left Side Figure F.25 Main Transformer Mountings Troubleshooting & Repair Invertec V250-S Input Idle Amps and Idle Watts Maximum Acceptable Output AT Minimum Output SettingsMinimum Acceptable Output AT Maximum Output Settings Retest After RepairInvertec V250-S Electrical Diagrams Invertec V250-S Invertec V250S Wiring Diagram Codes 10102Return to Section Wiring Diagram Codes 10187G2666 Control PC Board G2666 LayoutPower P.C. BD. Asbly Power PC Board G2684 LayoutRelay Coils Control PC Board G2666 SchematicFrom Control BD Power PC Board G2684 Schematic