Lincoln Electric LF-72/74 service manual Function Problems

Page 88

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F-4

TROUBLESHOOTING & REPAIR

F-4

LF-72/74

Observe Safety Guidelines detailed in the beginning of this manual.

PROBLEMS

POSSIBLE AREAS OF

RECOMMENDED

(SYMPTOMS)

MISADJUSTMENT(S)

COURSE OF ACTION

 

 

 

 

 

FUNCTION PROBLEMS

 

 

 

 

 

 

The wire drive does not feed wire

1. Power source not on

1.

Verify the power source is on

and the drive rolls do not spin

2. Possible tripped breaker

 

Verify power is being applied to

 

 

 

3. Faulty gun trigger

 

the wire feeder

 

 

 

 

4. Possible faulty control cable

2.

Verify the circuit breaker of the

 

 

wire feeder or the power source

 

 

 

 

 

 

has not tripped

 

 

3.

Check to see if the gun trigger is

 

 

 

working properly

 

 

4.

Check for cable continuity, and

 

 

 

for broken or bent pins.

The wire feeds erratically, or the

1. Wrong drive rolls installed.

1.

Verify the correct drive rolls and

motor LED lights.

 

 

inner wire guides are installed in

 

2. Possible problem with gun

 

the wire drive

 

3. Pressure arm or brake tension to

2.

Check for sharp bends in gun

 

tight.

 

liner

 

4. Examine the contact tip for wear

Check gun liner. The welding elec-

 

or proper size

trode should slide easily through

 

 

the gun. Verify proper gun liner is

 

 

installed

 

 

3.

Adjust brake tension. Adjust

 

 

 

pressure arm see FIGURE A.6

 

 

4.

Replace if necessary

 

 

5.

If using wire conduit, verify that

 

 

 

the wire slides easily through the

 

 

 

conduit.

 

 

6.

Perform the WIRE DRIVE

 

 

 

MOTOR TEST. Perform TACH

 

 

 

FEEDBACK TEST.

 

 

 

 

The wire continues to feed when

1. Trigger interlock switch in wrong

1.

Check if the 2 step/ trigger inter-

the gun trigger is released.

position.

 

lock switch is in the TRIGGER

 

 

 

INTERLOCK position.

 

2. Gun trigger shorted or stuck

 

 

 

 

2.

Verify operation of the gun trig-

 

 

 

ger. Check for shorted trigger

 

 

 

leads.

 

 

 

 

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 at 1-888-935-3877 for electrical troubleshooting assistance before you proceed.

LF-72/74 SINGLE/DUAL

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Contents LF-72/74 Safety Electric Shock can kill Welding Sparks can cause fire or explosion IiiPrécautions DE Sûreté Sûreté Pour Soudage a L’ArcMaster Table of Contents for ALL Sections Installation Section Table of ContentsSection A-1 Installation Amp Rating Duty CycleLocation Safety PrecautionMounting Bench Mount Swivel MountBoom Mount SuspendedWeld Cable Sizes Coaxial Weld Cables Weld Cable ConnectionAnalog Control Cable INSTALLATIONA-7Control Cable Connections Analog Miller Control Cable Adapter K2335-1 Miller Power Source Lincoln Wire FeederPin Function Wire Drive Systems Welding GUN/WIRE Feeder Trigger ConnectorRemote Sense Lead Specifications High Frequency ProtectionWelding GUNS, Torches and ACCES- Sories Magnum GUN and Cable AssembliesWire Drive Configuration Procedure for Changing Drive and Idle Roll SetsRolls.FIGURE A.4 Gun Receiver For use With Bushing Pressure ARM AdjustmentSet the pressure arm as follows See Figure A.6 Wire Reel Loading Weld Wire Routing Figure A.9Shielding GAS Connection Installing Electrode To install Lincoln conduit See Figure A.10bConduit Kits For Codes 11209, 11210, 11211 and aboveAluminum Wire Preparations Figure A.12bINSTALLATIONA-18 Base Model Bench Model Standard Duty Bench Model Heavy DutyTypical System Configurations CableLF-72/74 Operation Section Section B-1Operation GAS Input Work ConnectionProduct Description Common Welding AbbreviationsRecommended Processes Front Panel Controls and Connections Figure B.1 Case Front Controls DescriptionBurnback and Postflow Timer KIT Cold FEED/GAS Purge SwitchStep Trigger Interlock Switch Remote Voltage Control KITWire Feed Speed Knob Trigger Connector 5-PIN AmphenolGUN Receiver Bushing K1500-2 Trigger InterlockAccessories Section Section C-1Accessories Optional KitsLF-72s Accessories Key LF-72/74 Maintenance Section Section D-1Maintenance MaintenanceCalibration Specification Routine MaintenanceFigure D.1 Figure D.3 Major Component Location Section AA-1 Section AAAA-2 WFS Range Wire SizesModel AA-3 Figure AA.1AA-4 AA-5 AA-6 Coaxial Weld CableAA-7 INSTALLATIONAA-7K1797-xx AA-8 Drive Roll Kits Steel or Cored Wires AA-9AA-10 Figure AA.3AA-11 Changing the Gun Receiver BushingLation or changing drive rolls and/or GuidesAssembly of Drive Rolls and Wire Guides AA-12AA-13 Set the pressure arm as follows See Figure AA.8AA-14 AA-15 Loading 16 to 44 lb .3 20kg Spools See figure AA.8AA-16 Figure AA.11AA-17 Figure AA.12aAA-18 Figure AA.12bAA-19 AA-20INSTALLATIONAA-20 Common Equipment SET-UPSFigure AA.15 High Volume Production AA-21Figure AA.16 Portable Welding AA-22Section BB-1 Section BBBB-2 Fcaw Innershield or OutershieldRequired Equipment BB-3BB-4 Figure BB.1 Case Front Controls DescriptionK2426-1 and K2426-2 models BB-5K2426-3 model Switch BB-6Section CC-1 CC-2 CC-3 CC-4 CC-5 CC-6 Section DD-1 Section DDTo verify the wire feed speed Nal wiringWhen inching with gun trigger, electrode WFS knob setting Could remain energized Several secondsMAINTENANCEDD-3 DD-3Figure DD.3 Major Component Location DD-4Theory of Operation Section Section E-1Theory of Operation Return to SectionControl Board LF-72/74 Troubleshooting & Repair Section Section F-1Troubleshooting & Repair HOW to USE Troubleshooting GuidePC Board Troubleshooting Procedures Function Problems Function Problems Troubleshooting & Repair Drive Motor and Tach Feedback Test Test DescriptionTest Procedure Troubleshooting and Repair GAS Solenoid TestTest Procedure Figure F.3 Leads 552, 552BDiode Bridge Test 552B + 552A Wire Speed Potentiometer Test Wire Speed Potentiometer Test 14F-14PC Board Removal and Replacement Control PC Board Removal and Replacement Procedure Removal Procedure Replacement ProcedureTroubleshooting and Repair Wire Drive Motor and Gear BOX Removal and Replacement ProcedureProcedure Replacement Procedures SET UP Operation VerificationLF-72/74 Electrical Diagrams Section Section G-1Electrical Diagrams LF-72/74Timer KIT Board Normal Speed Micro Internal panel Motor Connecter Summary High Torque Setting engages Schematic Common Analog Control PC Board G4559 Sheet Electrical Diagrams Electrical Diagrams PC Board Assembly Common Analog Control G4560-2E0
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