Manuals / Lincoln Electric / Power Tools / Welding System

Lincoln Electric SVM170-A F-21, Troubleshooting And Repair, Return to Section TOC Section TOC

Models: SVM170-A

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F-21

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F-21	TROUBLESHOOTING AND REPAIR		F-21
	STATIC SCR RECTIFIER ASSEMBLY TEST (continued)
	FIGURE F.4 — LOCATION OF	FIGURE F.5 — SCR 1 TEST POINTS.

LEADS X2 AND X3.

NEGATIVE

CAPACITOR

BANK BUSS

BAR

LEADS X2 AND X3

CONNECTION

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6.Disconnect leads X2 and X3 (braided copper strap) from the negative capaci- tor bank buss bar using a 1/2 in. open end wrench. See Figure F.4.

7.Separate leads X2 and X3 from the negative capacitor bank buss bar. Be sure there is no electrical contact.

NOTE: DO NOT DISASSEMBLE THE SCR RECTIFIER HEAT SINK ASSEMBLY.

8.Test for high or infinite resistance from the anode to the cathode of SCR 1 using an analog ohmmeter. See Figure F.5.

9.Test for high or infinite resistance from the cathode to the anode of SCR 1 by reversing the meter leads. See Figure F.5.

a.If a high or infinite resistance is indi- cated for both tests 6 and 7, the SCR 1 is not “shorted”.

b.If a low resistance is indicated in either tests 6 or 7, the SCR is faulty. Replace the SCR assembly.

10.Repeat steps 6 and 7 to test SCR 2.

11.Reconnect leads X2 and X3 (braided copper strap).

12.Reconnect plugs J5 and J6.

13.If this test did not identify the problem, or to further test the SCR, go to the

Active SCR Rectifier Assembly Test.

POWER MIG 255C

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Lincoln Electric SVM170-A service manual F-21, Troubleshooting And Repair, STATIC SCR RECTIFIER ASSEMBLY TEST continued

Contents

SERVICE MANUAL POWER MIG 255CSafety Depends on You View Safety Info View Safety Info View Safety Info View Safety InfoFOR ENGINE powered equipment SAFETYELECTRIC AND MAGNETIC FIELDS may be dangerous CALIFORNIA PROPOSITION 65 WARNINGSARC RAYS can burn ELECTRIC SHOCK can killFUMES AND GASES can be dangerous SAFETYWELDING SPARKS can cause fire or explosion FOR ELECTRICALLY powered equipmentCYLINDER may explode if damaged SAFETYSAFETY PRÉCAUTIONS DE SÛRETÉReturn to Master TOC Return to Master TOC Return to Master TOC Return to Master TOCRETURN TO MAIN MENU MASTER TABLE OF CONTENTS FOR ALL SECTIONSTABLE OF CONTENTS INSTALLATIONINSTALLATION SECTION SECTION AINPUT - SINGLE PHASE ONLY TECHNICAL SPECIFICATIONS - POWER MIG 255CPHYSICAL DIMENSIONS INSTALLATIONUNCRATING THE POWER MIG 255C SAFETY PRECAUTIONSINPUT POWER, GROUNDING AND CONNECTION DIAGRAMS LOCATIONReturn to Section TOC INSTALLATIONReturn to Master TOC FIGURE A.1 - DUAL VOLTAGE MACHINE INPUT CONNECTIONSReturn to Section TOC INSTALLATIONReturn to Master TOC FIGURE A.2 - TRIPLE VOLTAGE MACHINE INPUT CONNECTIONSAUXILIARY POWER RECEPTACLES GUN AND CABLE INSTALLATIONSHIELDING GAS INSTALLATIONOPERATION TABLE OF CONTENTSOPERATION SECTION SECTION BObserve all safety information throughout this manual Read entire Operation section before operating the POWER MIG 255COPERATIONB-2 ELECTRIC SHOCK can killRECOMMENDED PROCESSES AND EQUIPMENT PRODUCT DESCRIPTIONWELDING CAPABILITY LIMITATIONSWIRE DRIVE ROLL WIRE SIZE CONVERSION PARTSDESCRIPTION OF CONTROLS OPERATIONWIRE REEL LOADING - READI REELS, SPOOLS OR COILS PROCEDURE FOR CHANGINGDRIVE AND IDLE ROLL SETS OPERATIONIDLE ROLL PRESSURE SETTING FEEDING WIRE ELECTRODEWIRE DRIVE CONFIGURATION TO START THE WELDERReturn to Master TOC OPERATIONReturn to Section TOC Return to Section TOC Return to Section TOC Return to Section TOCFAST OR SLOW RUN-IN MODE SELECTION SETTING RUN-IN SPEED ON STAN- DARD POWER MIG FEEDERINSTRUCTIONS TO ENTER SLOW RUN-IN INSTRUCTIONS TO ENTER FAST RUN-INWIRE FEED OVERLOAD PROTECTION AVOIDING WIRE FEEDING PROBLEMSFAN CONTROL INPUT LINE VOLTAGE PROTECTIONWELDING THERMAL OVERLOAD PROTECTION B-10OVERCURRENT PROTECTION OPERATIONACCESSORIES SECTION ACCESSORIESSECTION C TABLE OF CONTENTSDRIVE ROLL KITS TIMER KIT INSTALLATION Optional K1701-1ALTERNATIVE MAGNUM GMAW GUN AND CABLE ASSEMBLIES MAGNUM GUN CONNECTION KITCONNECTING THE SPOOL GUN TO THE POWER MIG 255C OPERATING INSTRUCTIONS FOR TIMER KITSPOOL GUN ACCESSORIESMAKING A WELD WITH THE MAGNUM SG SPOOL GUN MAKING A WELD WITH THE PRINCE XL SPOOL GUNFIGURE C.1 ACCESSORIESSG Spool Gun Wire Feed Speed ACCESSORIESReturn to Section TOC Return to Section TOC Return to Section TOC Return to Section TOCReturn to Section TOC Return to Section TOCReturn to Section TOC Return to Section TOCMAINTENANCE SECTION MAINTENANCESECTION D TABLE OF CONTENTSGUN CABLE CLEANING GENERAL MAINTENANCECONTACT TIP AND GAS NOZZLE INSTALLATION LINER REMOVAL AND REPLACEMENTGUN HANDLE DISASSEMBLY LINER REMOVAL, INSTALLATION AND TRIMMING INSTRUCTIONS FOR MAGNUM 250LMAINTENANCE Return to Master TOCTABLE D.2 ACCESSORIES AND EXPENDABLE REPLACE MAINTENANCED-4Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOCTHEORY OF OPERATION SECTION THEORY OF OPERATIONSECTION E TABLE OF CONTENTSAND MAIN TRANSFORMER INPUT LINE VOLTAGEDiagram are the subject of discussion POWER MIG 255CFEEDBACK CONTROL OUTPUT RECTIFICATION ANDDiagram are the subject of discussion POWER MIG 255CDiagram are the subject of discussion CONSTANT VOLTAGE OUTPUTPOWER MIG 255C THEORY OF OPERATIONAND FEEDBACK WIRE DRIVE MOTORDiagram are the subject of discussion POWER MIG 255CTHERMAL AND OVERLOAD PROTECTION WIRE FEED OVERLOAD PROTECTIONTHEORY OF OPERATION OVERCURRENT PROTECTIONTHEORY OF OPERATION SCR OPERATIONReturn to Section Return to MasterReturn to Section TOC Return to Section TOCReturn to Section TOC Return to Section TOCTROUBLESHOOTING AND REPAIR SECTION TROUBLESHOOTING AND REPAIRTABLE OF CONTENTS Return to Master TOC Return to Master TOC Return to Master TOCHOW TO USE TROUBLESHOOTING GUIDE F-2TROUBLESHOOTING AND REPAIRF-2Return to Section TOC Return to Master TOCPC BOARD TROUBLESHOOTING PROCEDURES TROUBLESHOOTING & REPAIRReturn to Section Return to Section TOC TOC Return to Master Return to Master TOC TOCPROBLEMS TROUBLESHOOTING GUIDESYMPTOMS MISADJUSTMENTSPROBLEMS TROUBLESHOOTING AND REPAIRSYMPTOMS MISADJUSTMENTSPROBLEMS TROUBLESHOOTING AND REPAIRSYMPTOMS MISADJUSTMENTSTROUBLESHOOTING AND REPAIR FUNCTION PROBLEMSPROBLEMS SYMPTOMSTROUBLESHOOTING AND REPAIR WIRE FEEDING PROBLEMSPROBLEMS SYMPTOMSTROUBLESHOOTING AND REPAIR WELDING PROBLEMSPROBLEMS SYMPTOMSTROUBLESHOOTING AND REPAIR F-10PROBLEMS SYMPTOMSF-11 TEST PROCEDURESMAIN TRANSFORMER TEST TEST DESCRIPTIONF-12 TEST PROCEDUREMAIN TRANSFORMER TEST continued TROUBLESHOOTING AND REPAIRTROUBLESHOOTING AND REPAIR F-13F-13 MAIN TRANSFORMER TEST continuedTROUBLESHOOTING AND REPAIR F-14F-14 MAIN TRANSFORMER TEST continuedRECTIFIER DIODE BRIDGE TEST F-15TROUBLESHOOTING AND REPAIR F-15RECTIFIER DIODE BRIDGE TESTING continued F-16TROUBLESHOOTING AND REPAIRF-16TEST PROCEDURE Return to Section TOC Return to Section TOCTROUBLESHOOTING AND REPAIR F-17RECTIFIER DIODE BRIDGE TESTING continued F-17F-18 F-18Return to Section TOC Return to Section TOCF-19 STATIC SCR RECTIFIER ASSEMBLY TESTTROUBLESHOOTING AND REPAIR F-19F-20 STATIC SCR RECTIFIER ASSEMBLY TEST continuedTROUBLESHOOTING AND REPAIR TEST PROCEDURETROUBLESHOOTING AND REPAIR F-21STATIC SCR RECTIFIER ASSEMBLY TEST continued F-21F-22 F-22Return to Section TOC Return to Section TOCF-23 ACTIVE SCR RECTIFIER ASSEMBLY TESTTROUBLESHOOTING AND REPAIR F-23F-24 ACTIVE SCR RECTIFIER ASSEMBLY TEST continuedTROUBLESHOOTING AND REPAIR TEST PROCEDURETROUBLESHOOTING AND REPAIR F-25ACTIVE SCR RECTIFIER ASSEMBLY TEST continued F-25TROUBLESHOOTING AND REPAIR F-26ACTIVE SCR RECTIFIER ASSEMBLY TEST continued F-26F-27 WIRE DRIVE MOTOR AND TACHOMETER FEEDBACK TESTTROUBLESHOOTING AND REPAIR F-27F-28 WIRE DRIVE MOTOR AND TACHOMETER FEEDBACK TEST continuedTROUBLESHOOTING AND REPAIR TEST PROCEDURETEST FOR SUPPLY VOLTAGE TO TACHOMETER F-29TROUBLESHOOTING AND REPAIR WIRE DRIVE MOTOR AND TACHOMETER FEEDBACK TEST continuedTEST FOR FEEDBACK VOLTAGE TO CONTROL BOARD F-30TROUBLESHOOTING AND REPAIR WIRE DRIVE MOTOR AND TACHOMETER FEEDBACK TEST continuedF-31 NORMAL OPEN CIRCUIT VOLTAGE WAVEFORMTROUBLESHOOTING AND REPAIR F-31F-32 TYPICAL OUTPUT VOLTAGE WAVEFORM - MACHINE LOADEDTROUBLESHOOTING AND REPAIR F-32TROUBLESHOOTING AND REPAIR F-33F-33 Return to Section TOC Return to Section TOC Return to Section TOCF-34 ABNORMAL OPEN CIRCUIT VOLTAGE OUTPUT CAPACITOR BANK NOT FUNCTIONINGTROUBLESHOOTING AND REPAIR F-34F-35 TYPICAL SCR GATE VOLTAGE WAVEFORMTROUBLESHOOTING AND REPAIR F-35F-36 F-36Return to Section TOC Return to Section TOCCONTROL PC BOARD REMOVAL AND REPLACEMENT COMPONENT REPLACEMENT PROCEDURESF-37 DESCRIPTIONREMOVAL AND REPLACEMENT CONTROL PC BOARD REMOVAL AND REPLACEMENT continuedPROCEDURE F-38F-39 CONTROL PC BOARD REMOVAL AND REPLACEMENT continuedTROUBLESHOOTING AND REPAIR F-39F-40 F-40Return to Section TOC Return to Section TOCF-41 WIRE DRIVE ASSEMBLY REMOVAL AND REPLACEMENTTROUBLESHOOTING AND REPAIR F-41F-42 WIRE DRIVE ASSEMBLY REMOVAL AND REPLACEMENT continuedTROUBLESHOOTING AND REPAIR F-42TROUBLESHOOTING AND REPAIR F-43WIRE DRIVE ASSEMBLY REMOVAL AND REPLACEMENT continued PROCEDUREF-44 F-44Return to Section TOC Return to Section TOCF-45 SCR OUTPUT RECTIFIER REMOVAL AND REPLACEMENTTROUBLESHOOTING AND REPAIR F-45F-46 SCR OUTPUT RECTIFIER REMOVAL AND REPLACEMENT continuedTROUBLESHOOTING AND REPAIR PROCEDURETROUBLESHOOTING AND REPAIR F-47SCR OUTPUT RECTIFIER REMOVAL AND REPLACEMENT continued F-47F-48 F-48Return to Section TOC Return to Section TOCF-49 CAPACITOR BANK REMOVAL AND REPLACEMENTTROUBLESHOOTING AND REPAIR F-49F-50 CAPACITOR BANK REMOVAL AND REPLACEMENT continuedTROUBLESHOOTING AND REPAIR PROCEDUREF-51 MAIN TRANSFORMER AND OUTPUT CHOKE REMOVAL AND REPLACEMENTTROUBLESHOOTING AND REPAIR F-51MAIN TRANSFORMER AND OUTPUT CHOKE REMOVAL AND REPLACEMENT continued F-52TROUBLESHOOTING AND REPAIRF-52PROCEDURE Return to Section TOCTROUBLESHOOTING AND REPAIR F-53MAIN TRANSFORMER AND OUTPUT CHOKE REMOVAL AND REPLACEMENT continued F-53F-54 F-54Return to Section TOC Return to Section TOCF-55 FAN MOTOR ASSEMBLY REMOVAL AND REPLACEMENTTROUBLESHOOTING AND REPAIR F-55F-56 FAN MOTOR ASSEMBLY REMOVAL AND REPLACEMENT continuedTROUBLESHOOTING AND REPAIR PROCEDURERETEST AFTER REPAIR WIRE SPEED RANGEF-57 OPEN CIRCUIT VOLTAGEReturn to Section TOC Return to Section TOCReturn to Section TOC Return to Section TOCELECTRICAL DIAGRAMS SECTION TABLE OF CONTENTSReturn to Master TOC Return to Master TOC Return to Master TOC Return to Master TOCWIRING DIAGRAM - ENTIRE MACHINE - CODE 11192 L12464 ELECTRICAL DIAGRAMSReturn to Section TOC Return to Section TOC Return to Section TOC Return to Section TOCELECTRICAL DIAGRAMS WIRING DIAGRAM - ENTIRE MACHINE CODE 11218 L12506Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOCELECTRICAL DIAGRAMS SCHEMATIC - ENTIRE MACHINE - G4752Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOCELECTRICAL DIAGRAMS SCHEMATIC - CONTROL PC BOARD - G4823-2D1 SHEETReturn to Section TOC Return to Master TOCSCHEMATIC - CONTROL PC BOARD - G4823-2D1 SHEET ELECTRICAL DIAGRAMSReturn to Section TOC Return to Master TOCSCHEMATIC - CONTROL PC BOARD - G4823-2D1 SHEET ELECTRICAL DIAGRAMSReturn to Section TOC Return to Master TOCELECTRICAL DIAGRAMS PC BOARD ASSEMBLY - CONTROL - G4824-2D1to Section TOC to Master TOCELECTRICAL DIAGRAMS SCHEMATIC - DISPLAY PC BOARD L10951Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOCG-10 PC BOARD ASSEMBLY - DISPLAY - L10952ELECTRICAL DIAGRAMS G-10SVM ERROR REPORTING FORM