Lincoln Electric DC-655 service manual Firing Board Schematic G2792

Page 104

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G-4

ELECTRICAL DIAGRAMS

G-4

Firing Board Schematic (G2792)

		7-17-98A
		G2792
	NOTE: Lincoln Electric assumes no responsibility for liablilities resulting from board level troubleshooting. PC Board repairs will invalidate your factory warranty. Individual Printed Circuit Board Components are not avail-	G2792
		7-17-98A
	able from Lincoln Electric. This information is provided for reference only. Lincoln Electric discourages board level troubleshooting and repair since it may compromise the quality of the design and may result in	7-17-98A
		DC 655
	danger to the Machine Operator or Technician. Improper PC board repairs could result in damage to the machine.	DC 655

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Contents Idealarc DC-655 Safety California Proposition 65 WarningsElectric Shock can kill Cylinder may explode if damaged Précautions DE Sûreté Master Table of Contents for ALL Sections Table of Contents Installation Section Installation Technical Specifications DC-655Input Power Three Phase Electrical Input Connections Safety PrecautionsSelect Suitable Location Input Power Supply Connections Input Supply Connection DiagramOutput Connections Electrode and Work CablesAuxiliary Power Control Connections Auxiliary Power TableTerminal Strip 1 T.S.1 Terminal Strip 2 T.S.2Table of Contents Operation Section OPERATIONB-2 Operating InstructionsDesign Features Advantages OperationGeneral Description Recommended Processes and EquipmentDC-655 Figure B.2 Lower Case Front Controls & Connections Case Back Connections Auxiliary PowerMachine Protection Over Current Protection Shutdown Remote Control Leads Fault Protection SHUTDOWN1Thermal Shutdown CV Mode CURRENT-LIMITING CC Mode HOT StartCC Mode ARC Force CC Mode ARC Gouging Welding PerformanceTable of Contents Accessories Field Installed Options Remote Output ControlAutomatic Wire Feeders SEMI-AUTOMATIC Wire FeedersSet the Idealarc DC-655 Power toggle Accessories Semiautomatic Wire Feeders Connecting the LN-7 to the Idealarc DC-655 Terminal Strip GND Negative Positive Figure C.4 Idealarc DC-655 Table of Contents Maintenance General Maintenance Electric Shock can killFigure D.1 General Component Locations Idealarc DC-655 Table of Contents Theory of Operation Section Theory of Operation Down Circuits Protective Devices and Shutdown Circuits SCR Operation Figure E.4 SCR OperationIdealarc DC-655 Table of Contents Troubleshooting & Repair Section Troubleshooting & Repair HOW to USE Troubleshooting GuidePC Board Troubleshooting Procedures Troubleshooting Guide Board LED Chart ControlLED Chart OutputBridge Test Perform the SCR Bridge TestTransformer Test See the Idle Shut Down TimerMain Function Problems Thermal Fan/Snubber PC Troubleshooting & Repair Welding Problems Mode Current Limiting See the Control BoardMaterials Needed Internal Trigger Circuit TestTest Description Internal Trigger Circuit Test Test ProcedureTrigger Diagram Simplified Trigger Diagram. If a resistance SectionFigure F.3 Simplified Trigger Diagram Firing Board Test Firing Board Test Figure F.4 Firing Board Trigger Circuit Test Points and LEDsMain Transformer Test Figure F.5 14-PIN Receptacle Figure F.4 Main Transformer T1 Voltage Test Main Transformer T1 Voltage Test Figure F.6 Input Contactor and Primary LeadsTroubleshooting & Repair Figure F.8 Terminal Strip Figure F.9 Firing Board Plug J5 Pins Control Transformer T2 Test Control Transformer T2 Test Figure F.10 Control TransformerHigh Voltage is present at Control Board Transformer T3 Test Control Board Transformer T3 Test Perform the Control Transformer T2 TestInput Contactor Test Input Contactor Test Transformer T2 TestTest for Contact Continuity Figure F.13 Input Contactor Test ConnectionsStatic SCR Test Static SCR Test Figure F.15 Heat Sink Test Points Active SCR Test Active SCR Test Figure F.17 Heat Sink Test Points Anode Cathode Thermal FAN/SNUBBER Board LED Chart LED Functions and IndicationsControl Board LED Chart LED # LED Functions and IndicationsScope Settings Maximum Output Setting no Load Normal Open Circuit Voltage Waveform Constant Voltage MIGMinimum Output Setting no Load Troubleshooting & Repair Typical SCR Gate Voltage Waveform Constant Voltage MIG Installation Input Contactor CR1 CLEANING/REPLACEMENT DescriptionInput Contactor CR1 CLEANING/REPLACEMENT Cleaning ProcedureSCR Rectifier Bridge Removal Replacement Procedure SCR Rectifier Bridge Removal Replacement ProcedureProcedure Reassembly SCR Rectifier Bridge LEG Assembly Mounting BracketsMain Transformer and Choke Removal Replacement Procedure Main Transformer and Choke Removal Output Choke RemovalMain Transformer Removal Retest After Repair Input Idle Amps and WattsSVM Error Reporting Form Section G Electrical Diagrams Control Board Schematic G3384 Firing Board Schematic G2792 Thermal Fan/Snubber Board Schematic L10123 Control Board Layout G3385-1 Firing Board Layout G2699-2 Thermal Fan/Snubber Board Layout L10124-1 Return to Section TOC