Static SCR Rectifier Assembly Test | Lincoln Electric SVM170-A

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F-20	TROUBLESHOOTING AND REPAIR	F-20
	STATIC SCR RECTIFIER ASSEMBLY TEST (continued)

FIGURE F.3 — REMOVE PLUGS J6 AND J5 TO PERFORM STATIC RECTIFIER ASSEMBLY TEST.

J6

J5

J3

J8

J1

J4

J2

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TEST PROCEDURE

1.Disconnect main AC input power to the machine.

2.Remove the case top and side panels with a 3/8 in. nutdriver.

3.Remove the tool tray with a 5/16 in. nut- driver.

4.Verify that the capacitors have completely discharged with a volt- ohmmeter.

5.Disconnect plugs J6 and J5 from the control board . This electrically isolates the SCR bridge assembly. See Figure F.3.

POWER MIG 255C

Image 60

Lincoln Electric SVM170-A service manual Static SCR Rectifier Assembly Test

Contents

Power MIG 255C Safety California Proposition 65 Warnings Electric Shock can kill Welding Sparks can cause fire or explosion Iii Précautions DE Sûreté Sûreté Pour Soudage a L’Arc Master Table of Contents For ALL Sections Installation Table of Contents Installation Section Technical Specifications Power MIG 255C Safety Precautions Uncrating the Power MIG 255CInput POWER, Grounding and Connection Diagrams Location Installation Figure A.2 Triple Voltage Machine Input Connections GUN and Cable Installation Auxiliary Power ReceptaclesShielding GAS Table of Contents Operation Section Operation OPERATIONB-2 Wear eye, ear and body protec- tion Product Description Recommended Processes and EquipmentWelding Capability Limitations Wire Size Conversion Parts Wire Drive RollDescription of Controls Procedure for Changing Wire Reel Loading Readi REELS, Spools or CoilsDrive and Idle Roll Sets Feeding Wire Electrode Idle Roll Pressure SettingWire Drive Configuration To Start the Welder Figure B.4 When Timer Option is not installed Instructions to Enter Slow RUN-INInstructions to Enter Fast RUN-IN Making a Weld Avoiding Wire Feeding Problems Wire Feed Overload ProtectionFAN Control Input Line Voltage Protection Welding Thermal Overload Protection Overcurrent Protection Accessories Table of Contents Accessories Section Drive Roll Kits Magnum GUN Connection KITK363P READI-REEL Adapter Dual Cylinder Mounting KIT K1702-1 Operating Instructions for Timer KIT Connecting the Spool GUN to the Power MIG 255CK1738-1 Spool Gun Hanger Accessory Spool GUN Making a Weld with the Prince XL Spool GUN Making a Weld with the Magnum SG Spool GUN SG Spool Gun Wire Feed Speed Power MIG Maintenance Table of Contents Maintenance Section GUN Tubes and Nozzles General Maintenance GUN Cable CleaningContact TIP and GAS Nozzle Installation Liner Removal and Replacement GUN Handle Disassembly Table D.1 MAINTENANCED-4 English Metric Description Table of Contents Theory of Operation Section Theory of Operation Input Line Voltage Main Transformer Output Rectification Feedback Control Constant Voltage Output Figure E.4 Constant Voltage Output Wire Drive Motor Feedback Wire Feed Overload Protection Thermal and Overload Protection SCR Operation Figure E.6 SCR Operation Power MIG 255C Troubleshooting and Repair Table of Contents Troubleshooting and Repair Section 2TROUBLESHOOTING and REPAIRF-2 HOW to USE Troubleshooting Guide PC Board Troubleshooting Procedures Troubleshooting Guide Output Problems Problems Possible Areas Symptoms Misadjustments Course of ActionTrolyte in these capacitors is Toxic. Avoid contact with any Perform the SCR Rectifier Function Problems Wire Feeding Problems Welding Problems Welding Problems Test Procedures Main Transformer TestTest Description Materials Needed Test Procedure ON/OFF Power Switch will be hot during these tests 115VAC 16J5 8J5 206 3J5 Rectifier Diode Bridge Test 16TROUBLESHOOTING and REPAIRF-16 Figure F.2 G3521 Rectifier Diode Bridge Location 208 206 28 VAC 209 354 206 36 VDC Power MIG 255C Static SCR Rectifier Assembly Test Static SCR Rectifier Assembly Test Active SCR Rectifier Assembly Test Power MIG 255C Active SCR Rectifier Assembly Test Active SCR Rectifier Assembly Test Figure F.7 Location Leads X2 Figure F.8 Wire Drive Motor and Tachometer Feedback Test Wire Drive Motor and Tachometer Feedback Test 4J1 Test for Supply Voltage to Tachometer 515B 206B 15 VDC 5J1 1J1 Test for Feedback Voltage to Control Board 555 206B To 3.5 VDC 6J1 1J1 Normal Open Circuit Voltage Waveform Volts Machine Loaded to 250 Amps AT 26 VDC Scope Settings Typical Output Voltage Waveform Machine Loaded Machine Loaded to 220 Amps AT 22 VDC Scope Settings Troubleshooting and Repair Typical SCR Gate Voltage Waveform Power MIG 255C Component Replacement Procedures Control PC Board Removal and ReplacementDescription Removal and Replacement Procedure Figure F.11 Control Board Mounting Power MIG 255C Wire Drive Assembly Removal and Replacement Wire Drive Assembly Removal and Replacement Procedure Power MIG 255C SCR Output Rectifier Removal and Replacement SCR Output Rectifier Removal and Replacement Figure F.15 Right Heat Sink Lead Disconnection Power MIG 255C Capacitor Bank Removal and Replacement Capacitor Bank Removal and Replacement Main Transformer and Output Choke Removal and Replacement 52TROUBLESHOOTING and REPAIRF-52 Main Transformer and Output Choke TOC Power MIG 255C FAN Motor Assembly Removal and Replacement FAN Motor Assembly Removal and Replacement Wire Speed Range Retest After RepairOpen Circuit Voltage Input Volts/Hertz Power MIG 255C Electrical Diagrams Section Section G-1 Electrical Diagrams Wiring Diagram Entire Machine Code 11192 L12464 Wiring Diagram Entire Machine Code 11218 L12506 Schematic Entire Machine G4752 Schematic Control PC Board G4823-2D1 Sheet Electrical Diagrams Electrical Diagrams PC Board Assembly Control G4824-2D1 Item Used with QTY Part Number Description Schematic Display PC Board L10951 Powermig PC Board Assembly Display L10952 Lincoln Electric CO SVM Error Reporting Form