Lincoln Electric SVM188-A service manual Anode Cathode Remove Insulating Paint, SCR Bridge Test

Page 70

to Section TOC

Return to Master TOC

F-30

TROUBLESHOOTING AND REPAIR

F-30

SCR BRIDGE TEST(continued)

FIGURE F.14 – SCR BRIDGE ASSEMBLY

Return

Return to Section TOC

Return to Section TOC

Return to Section TOC

Return to Master TOC

Return to Master TOC

Return to Master TOC

ANODE

CATHODE

REMOVE

INSULATING

PAINT

PROCEDURE

STATIC TEST

1.Disconnect the input power from the DC-600.

2.Remove the top and side panels and drop the nameplate to access the PC Boards.

3.Unplug the Molex connectors from both the Control Board and the Firing Board.

4.Scratch off some of the insulating paint from each of the six heat sinks (anodes) and the base plate (cathode). See Figure F.14.

5.Using the analog ohmmeter:

•Measure the resistance from each Anode to the Cathode plate with the Positive meter lead on the Anodes. The resistance should be very high or ‘open’.

•Reverse the meter leads and measure all the same points. The readings should be very high or ‘open’, and typically, will all be similar.

6.If any of the test points shows a low resistance, dis- connect the Snubber Board from that SCR. If the reading is still low, the SCR is defective.

7.Continue to the Active Test.

The Active test will require constructing a test cir- cuit or use of a commercial SCR Tester. See Figure F.15.

DC-600

Image 70

Contents DC-600 ISAFETYi Fumes and Gases SafetyElectric Shock can kill Can be dangerousPowered equipment For ElectricallyPrécautions DE Sûreté Sûreté Pour Soudage a L’ArcElectromagnetic Compatibility EMC Safety Master Table of Contents for ALL Sections Table of Contents Installation Section Installation Technical Specifications DC-600Electric Shock can Kill Safety PrecautionsSelect Proper Location Electrical Input Connections Fuse and Wire SizesGround Connection Reconnect Procedure Connection for Highest Rating Plate VOLTAGE, 50 or 60 HZConnection for 440 Volts 50 or 60 HZ V 60HZ See Machine Rating Plate for Required Input Supply Voltage ELECTRODE, Work and #21 Lead Output ConnectionsConnections Terminal Strip 1 T.S.1 Auxiliary Power Control ConnectionsTerminal Strip 2 T.S.2 DC-600 Table of Contents Operation Section Safety Precautions OperationGeneral Description Design Features AdvantagesRecommended Processes and Equipment Welding Capability Meanings of Graphical Symbols on Case FrontOFF Input Power Output Control Output Voltage CurrentMeaning of Graphical Symbol for Ground CON- Nection Controls and SettingsAuxiliary Power in MS-RECEPTACLE OVERLOAD, OVERCURRENT, and Fault ProtectionWelding Procedure Recommendations Remote Control of Machine OperationOperating Steps NA-3 Automatic Wire Feeder RemoteLN-8 or LN-9 SEMI-AUTOMATIC Wire Feeder LN-7 and Other Constant Wire FeedersDC-600 Table of Contents Accessories Section Factory or Field Installed Options AccessoriesWire Feeders and Tractors Field Installed OptionsFigure C.2 MULTI-PROCESS Switch Cable Connections Accessories Table of Contents Maintenance Section Safety Precautions Electric Shock can Kill MaintenanceRoutine and Periodic Maintenance 1TABLE of CONTENTS-THEORY of Operation Section E-1 Theory of Operation Input Circuit and Main TRANS- FormerRectification Firing CIRCUIT, Control CIR- Cuit and RectificationFiring Board Thermal Protection SCR Operation DC-600 1TABLE of Contents Troubleshooting and Repair F-1 2TROUBLESHOOTING and REPAIRF-2 HOW to USE Troubleshooting GuideTroubleshooting and Repair PC Board Troubleshooting ProceduresControl Feeder. See Protective Devices Check all three phase input Output Control J1,Pin2. See Wiring Diagram Wiring Diagram Test Description PC Board Troubleshooting GuideMaterials Needed PC Board Troubleshooting Guide Control Board Figure F.2 Control Board LEDsDC-600 Internal Trigger Circuit Test Procedure Internal Trigger Circuit TestInternal Trigger Circuit Test 75 76DC-600 Firing Board Test Firing Board Test Control Board Test Control Board Test Figure F.7 Control BoardMain Transformer Voltage Test Main Transformer Voltage Test Figure F.8 Input Contactor and Reconnect PanelFigure F.9 Transformer Secondaries Main Transformer Voltage Test Control Transformer Test Procedure Control Transformer TestInput Contactor Test Input Contactor Test Voltage TestSCR Bridge Test Anode Cathode Remove Insulating Paint SCR Bridge TestActive Test Scope Settings Maximum Output Setting no Load Minimum Output Setting no Load 35TROUBLESHOOTING and REPAIRF-35 2V/Div Volts DC-600 Input Contactor CR1 CLEANING/REPLACEMENT Cleaning Procedure Input Contactor CLEANING/REPLACEMENT ProcedureContactor Replacement Procedure SCR Rectifier Bridge Removal and Replacement Procedure Removal Procedure 42TROUBLESHOOTING and REPAIRF-42Removal and Replacement Procedure SCR Rectifier BridgeReplacement Procedure Insulator Lock Washer Plain Washer Output Snubber LeadDC-600 Main Transformer and Choke Removal and Replacement Removal and Replacement Main Transformer and ChokeRemoval Procedure Weld Input Idle Amps and Watts Maximum Open Circuit VoltagesDC-600 Table of Contents Diagram Section Electrical Diagrams Wiring Diagram 230/460/575 Volt Machines G3506-1 Schematic Complete Machine G3575 Schematic Control PC Board G3408-1 Control PC Board Assembly G3409-1 Schematic Firing PC Board G3741-1