Lincoln Electric Comprehensive Troubleshooting Guide for Lincoln DC 655 Welder
Page 54

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F-12

F-12

 

 

TROUBLESHOOTING & REPAIR

 

 

Observe Safety Guidelines

TROUBLESHOOTING GUIDE

detailed in the beginning of this manual.

PROBLEMS

POSSIBLE AREAS OF

RECOMMENDED

 

(SYMPTOMS)

MISADJUSTMENT(S)

COURSE OF ACTION

 

 

 

 

 

 

 

 

WELDING PROBLEMS

 

 

 

The arc is variable or sluggish.

1.

Check the three-phase input

1. Check the weld mode switch

 

 

line voltage at the machine.

(SW2) and associated leads for

 

 

The input voltage must match

proper operation or loose or

 

 

the rating plate and reconnect

faulty

connections.

See the

 

 

panel configuration.

 

Wiring Diagram.

 

 

2. Make

sure

the machine’s set-

2. Perform the Firing Board Test.

 

 

tings are correct for the welding

3. Perform the SCR Bridge Test.

 

 

process.

 

 

 

 

 

 

 

 

 

 

3.

Check

the

welding

cables for

4. Perform the Main Transformer

 

Test.

 

 

 

 

loose

or

faulty connections.

 

 

 

 

 

 

 

 

 

Also make sure cables are sized

5. The control board may be

 

 

correctly for the welding cur-

faulty.

See the Control Board

 

 

rent.

 

 

 

LED Chart.

 

 

4.

See

CV

Mode

Current

 

 

 

 

 

Limiting.

 

 

 

 

 

 

 

 

 

The Arc Force Control (R4) has no

1.

The Arc Force Control is active

1. Check the Arc Force Control

effect on the arc.

 

only in the CC Stick mode.

potentiometer (R4) for the cor-

 

2.

The effect

of the

Arc Force

rect

resistance and

proper

 

operation. Normal resistance is

 

 

Control will be less noticeable

 

 

10,000 ohms.

 

 

 

at high welding currents. Weld

 

 

 

 

 

 

 

 

at low currents (less than 150

2. Check the continuity of leads

 

 

amps) and check the Arc Force

#321, #322 and #328 from the

 

 

control function.

 

Arc Force Control to the control

 

 

 

 

 

 

board. See the Wiring Diagram.

 

 

 

 

 

 

3. The control board may be

 

 

 

 

 

 

faulty. Replace.

 

 

 

 

 

 

 

 

 

 

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con- tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-800-833-9353.

IDEALARC DC-655

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Page 53 Page 55
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 Safety Precautions Select Suitable LocationElectrical Input Connections 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 InstructionsGeneral Description Design Features AdvantagesOperation Recommended Processes and EquipmentDC-655 Figure B.2 Lower Case Front Controls & Connections Auxiliary Power Machine ProtectionCase Back Connections Remote Control Leads Fault Protection SHUTDOWN1 Thermal ShutdownOver Current Protection Shutdown CC Mode ARC Force CC Mode ARC Gouging CV Mode CURRENT-LIMITINGCC Mode HOT Start 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 ControlBridge Test LED ChartOutput Perform the SCR Bridge TestSee the Idle Shut Down Timer MainTransformer Test Function Problems Thermal Fan/Snubber PC Troubleshooting & Repair Welding Problems Mode Current Limiting See the Control BoardInternal Trigger Circuit Test Test DescriptionMaterials Needed Test Procedure Trigger DiagramInternal Trigger Circuit Test 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 Replacement Procedure ProcedureSCR Rectifier Bridge Removal 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
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