Lincoln Electric SVM151-A service manual Test Procedure for the Left Side Power Module

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TROUBLESHOOTING & REPAIR

CHOPPER PC BOARD INPUT VOLTAGES AND

RESISTANCE TEST (CONTINUED)

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Test Procedure for the Left Side

Power Module

1.Locate the Power Module Capacitor termi- nals. Using the 7/16" wrench, disconnect leads #X1, #X4, #401, #401A and the cop- per straps. Carefully electrically isolate these leads and straps from the capacitor terminals and heat sink assembly. See

Figure F.6.

2.Using the 3/8" nut driver, remove the four screws holding the case back to the tunnel assembly. This will provide access to the IGBT heat sinks.

3.Using the analog ohmmeter, connect the positive meter probe to the positive copper strap and the negative meter probe to the IGBT heat sink. (This is the inner heat sink.) See Figure F.6 for test point loca- tions. The resistance should be very high (over 20,000 ohms). If the resistance is low, then either the IGBT is shorted or the diode D5 is shorted. Disconnect the small D5 cathode lead to isolate the problem. It is possible that both devices may be faulty.

4.Reverse the meter leads. The resistance should be low (approximately 100 ohms). If the resistance is high, the diode D5 may be open.

5.Using the analog ohmmeter, check diode module D3. Connect the negative meter probe to the negative copper strap connect- ed to the diode module and the positive probe to the heat sink. See Figure F.6 for the test point locations. The resistance should be very high (over 20,000 ohms). If the resistance is low, the diode module D3 may be shorted.

6.Reverse the meter leads. The resistance should be low (approximately 100 ohms). If the resistance is high, the diode module D3 may be open.

7.Repeat Steps 1 through 5 for the Right Side Power Module. See the Wiring Diagram.

8.Replace all leads previously removed. See Figure F.6 and the Wiring Diagram. Torque the capacitor bolts to 50 to 60 inch pounds.

CHOPPER PC BOARD VOLTAGE TESTS FOR BOTH LEFT AND RIGHT SIDES

1.Locate Plug P45(A) and disconnect it from J45(A). See Figure F.6.

WARNING

ELECTRIC SHOCK can kill.

With the input power ON, there are high volt- ages inside the machine. Do not reach into the machine or touch any internal part of the machine while power is on.

2.Carefully apply the correct input voltage to the Multi-Weld 350 (50 – 113 VDC). The machine should be in the CC mode and the CC Slope switch should be in the Stick/Gouge position.

3.Turn the machine on and carefully check for 18.0 – 21.0 VDC at P45(A) pin 1 (+) to P45(A) pin 3 (-). This is the 20 VDC supply from the Analog Control Power Supply PC Board to the Chopper PC Board.

NOTE: Be careful not to touch the capacitor terminals.

4.Also carefully check for 11.0 – 14.0 VDC at P45(A) pin 7 (+) to P45(A) pin 9 (-). This is the Pulse Width Modulation Signal from the Weld Control Board to the Chopper PC board.

5.If any of the voltages are not present, check associated leads and plugs for loose or faulty connections. See the Wiring Diagram.

6.Remove the input power and perform the

Power Module Capacitor Discharge Procedure.

7.Reconnect the plugs previously discon- nected.

8.If finished testing, perform the Case Cover Replacement procedure.

MULTI-WELD 350

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Contents Multi-Weld TM 350 Arc Converter Safety California Proposition 65 WarningsElectric Shock can kill Welding Sparks can cause fire or explosion IiiPrécautions DE Sûreté Sûreté Pour Soudage a L’ArcMaster Table of Contents for ALL Sections Table of Contents Installation Section Installation Technical Specifications MULTI-WELD 350 K1735-1Safety Precautions QUICK-CONNECT PIG-TAILSWork Connection Case GroundingFixed Parallel Operation Power Source Setup Converters Cable Size On Cable AWG mm2Table of Contents Operation Section Operating Instructions Safety InstructionsOperation Portable Product DescriptionVersatile MULTI-SYSTEM Power Source PIG-TAIL Leads and ConnectorsRecommended Equipment and Processes Distribution BOXRemote Output Control Options CV Mode Wire WeldingCC Mode Stick Welding and Gouging Input Power/ Mode Switch has three positions Front Panel ControlsRecessed Panel Controls For CC STICK/GOUGE Mode only Paralleled ConvertersTransporting and Storage of the MULTI-WELD Cable HandlingProtection Features MULTI-WELD Table of Contents Accessories Section Accessories OPTIONS/ACCESSORIESSemiautomatic Welding Accessories Connection of Lincoln Electric Wire FeedersTo Work MULTI-WELD Section D-1 Table of ContentsMaintenance Section See additional warning information throughout this manual MaintenanceMaintenance Service Figure D.2 Major Component LocationsMULTI-WELD Table of Contents Theory of Operation Section Theory of Operation General DescriptionPower Modules and FEED- Back Figure E.3 Power Modules and FeedbackAnalog Control Power Supply Board and Weld Control Board Mode Selector and Output Controls Figure E.5 Mode Selector and Output ControlsOVER-VOLTAGE Protection Insulated Gate Bipolar Transistor Igbt Operation Pulse Width Modulation 8E-8Chopper Technology Fundamentals 70-80VDCMULTI-WELD Table of Contents Troubleshooting & Repair Section Troubleshooting & Repair HOW to USE Troubleshooting GuidePC Board Troubleshooting Procedures PC Board can be damaged by static electricityTroubleshooting Guide Power Supply Board TestPerform the DC Buss Supply Board TestSpecifications Perform the Input ContactorCoil Resistance and Supply Voltage TestInput Voltage and Resistance TestFunction Problems See the Digital Meter Calibra Analog Control Power Supply Board TestTion and Adjustment Test Perform the DC Buss Supply Welding Problems Troubleshooting & Repair Troubleshooting & Repair Materials Needed Case Cover Assembly Removal Replacement ProcedureTest Description Removal Procedure Replacement ProcedurePower Module Capacitor Discharge Procedure Procedure Figure F.2 Power Module Capacitor Terminal DischargeInput Contactor Coil Resistance and Supply Voltage Test Coil Test Procedure Perform the Power Module Capacitor Discharge procedureInput Contactor Coil Resistance Supply Voltage Test Leads #303A #330Test for Contact Continuity Supply PC Board TestAnalog Control Power Supply PC Board Test Test Procedure Figure F.4 Analog Control Power Supply PC BoardPower Supply PC Board Test DC Buss Power Supply PC Board Test DC Buss Power Supply PC Board P46 P47Table F.2 DC Buss Power Supply PC Board Voltage Table Chopper PC Board Input Voltages and Resistance Test Figure F.6 Power Module Assembly Details Chopper PC Board Input Voltages Resistance TestTest Procedure for the Left Side Power Module Power Module Capacitor Discharge ProcedureNormal Open Circuit Voltage Waveform CC Mode Input Voltage Applied 75 VDCScope Settings CV Mode Output Control AT Maximum Machine Loaded to 350 Amps AT 34 Volts CC-STICK Mode Normal Weld Voltage WaveformMachine Loaded to 350 Amps AT 34 Volts CV Mode CV Mode Output Control AT Minimum Case Front Assembly Removal and Replacement DescriptionReplace the case cover Weld Control or Peripheral PC Board Removal and Replacement Figure F.8 Case Front Assembly Details Replacement Procedure Description Digital Meter Removal Procedure Lens Bezel Spacer Seal KnobOutput Control Potentiometer Removal Procedure Refer to Figure F.9Input Contactor Removal and Replacement Figure F.10 Input Contactor Assembly Details Lead #331Replacement Procedure Input Diode Removal and Replacement Figure F.11 Input Diode Assembly Details 25-27 300-324 Refer to Figure F.11FAN Motor Assembly Removal and Replacement Figure F.12 FAN Motor Assembly Details Perform the Input Diode Replacement procedure Perform the Input Diode Removal proce- durePower Capacitor Removal and Replacement Figure F.13 Power Capacitor Mounting Details Reassembly Chopper PC Board and Diode Module Removal and Replacement Chopper PC Board Removal and Replacement RemovalReplacement Refer to Figure F.14Diode Module Removal and Replacement Figure F.15 Diode Module Mounting DetailsRefer to Figure F.15 Figure F.16 Diode Module Tightening Sequence Retest After Repair Idle AmpsOpen Circuit Voltages Load TestElectrical Diagrams Table of Contents Electrical Diagrams SectionMULTI-WELD 350 Wiring Diagram Wiring Diagram MULTI-WELDSchematic Control PC Board #1 Schematic Control PC Board #2 Schematic Control PC Board #3 Schematic Control PC Board #4 Schematic Control PC Board #5 PC Board ASSEMBLY-CONTROL RESISTOR,SMD,1W,243OHMS,1%Schematic Peripheral Printed Circuit Board PC Board ASSEMBLY-PERIPHERAL PC Board Reference Description DesignatorsSchematic Power Printed Circuit Board PC Board ASSEMBLY-POWER Return to Section Return to Section TOC To Section TOCSchematic Analog Printed Circuit Board PC Board ASSEMBLY-ANALOG Schematic BY-PASS Printed Circuit Board PC Board Assembly BY-PASS Schematic Chopper Printed Circuit Board 19303 MPC Board Assembly Chopper SVM Error Reporting Form