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Lincoln Electric SVM170-A manual

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Table of contents for the manual

  • Page 1

    PO WER MIG 255C SVM170-A October , 2006 Safety Depends on Y ou Lincoln arc welding and cutting equipment is designed and built with safety in mind. However , your overall safety can be increased by pr oper installation . . . and thoughtful operation on your part. DO NOT INST ALL, OPERA TE OR REP AIR THIS EQUIPMENT WITHOUT READ- ING THIS MANUAL AND [...]

  • Page 2

    Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC FOR ENGINE powered equipment. 1.a. T urn the engine off before troubleshooting and maintenance work unless the maintenance work requires it to be running. ____________________________________________________ 1.b. Operate engines in open, well-ventilated areas or ven[...]

  • Page 3

    Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC ARC RA YS can burn. 4.a. Use a shield with the proper filter and cover plates to protect your eyes from sparks and the rays of the arc when welding or observing open arc welding. Headshield and filter lens should conform to ANSI Z87. I standards. 4.b. Use suitable c[...]

  • Page 4

    Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC FOR ELECTRICALL Y powered equipment. 8.a. T urn off input power using the disconnect switch at the fuse box before working on the equipment. 8.b. Install equipment in accordance with the U.S. National Electrical Code, all local codes and the manufacturer ’s recomm[...]

  • Page 5

    Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC PRÉCAUTIONS DE SÛRETÉ Pour votre propre protection lire et observer toutes les instructions et les précautions de sûreté specifiques qui parraissent dans ce manuel aussi bien que les précautions de sûreté générales suiv- antes: Sûreté Pour Soudage A L ?[...]

  • Page 6

    v v POWER MIG 255C MASTER T ABLE OF CONTENTS FOR ALL SECTIONS Page Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i-iv Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section A Operation . . . . . . . . . . . . . . . . [...]

  • Page 7

    SECTION A INST ALLA TION POWER MIG 255C SECTION A T ABLE OF CONTENTS -INST ALLA TION SECTION- Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section A T echnical Specifications — POWER MIG 255C . . . . . . . . . . . . . . . . . . . . . . . [...]

  • Page 8

    A-2 POWER MIG 255C A-2 INST ALLA TION 75°C Copper Wire 75°C Copper Wire in Conduit in Conduit Input Ampere A WG (IEC) Sizes A WG (IEC) Sizes Input V oltage/ Fuse or Breaker Rating On (For lengths (For lengths Frequency (Hz) Size (Super Lag) Nameplate up to 100 ft) exceeding 100 ft) 208/60 60 56 8 (10 mm 2 )6 (16 mm 2 ) 230/60 60 52 10 (6 mm 2 )8 [...]

  • Page 9

    INPUT POWER, GROUNDING AND CONNECTION DIAGRAMS ------------------------------------------------------------------------ 1. Before starting the installation, check with the local power company if there is any question about whether your power supply is adequate for the voltage, amperes, phase, and frequency spec- ified on the welder nameplate. Also [...]

  • Page 10

    4. Using the instructions in Figure A.3 , have a qual- ified electrician connect the receptacle or cable to the input power lines and the system ground per the U.S. National Electrical Code and any applic- able local codes. See T echnical Specifications at the beginning of this chapter for proper wire sizes. For long runs over 100 feet, larger copp[...]

  • Page 11

    A-5 INST ALLA TION POWER MIG 255C A-5 FIGURE A.3 — RECEPT ACLE DIAGRAM. CONNECT TO A SYSTEM GROUNDING WIRE. SEE THE UNITED ST A TES NA TIONAL ELECTRICAL CODE AND/OR LOCAL CODES FOR OTHER DET AILS AND MEANS FOR PROPER GROUNDING. CONNECT TO HOT WIRES OF A THREE-WIRE, SINGLE PHASE SYSTEM OR T O ONE PHASE OF A TWO OR THREE PHASE SYSTEM. OUTPUT POLARI[...]

  • Page 12

    A-6 INST ALLA TION POWER MIG 255C A-6 GUN AND CABLE INST ALLA TION The Magnum 250L gun and cable provided with the POWER MIG 255C is factory installed with a liner for 0.035-0.045 in. (0.9-1.2 mm) electrode and an 0.035 in. (0.9 mm) contact tip. Install the 0.045 tip (also pro- vided) if this wire size is being used. T urn the welder power switch o[...]

  • Page 13

    SECTION B OPERA TION SECTION B POWER MIG 255C T ABLE OF CONTENTS -OPERA TION SECTION- Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section B Product Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [...]

  • Page 14

    B-2 OPERA TION B-2 POWER MIG 255C Read entire Operation section before operating the POWER MIG 255C. ELECTRIC SHOCK can kill. • Do not touch electrically live parts or electrode with skin or wet clothing. Insulate yourself from work and ground. • Always wear dry insulating gloves. FUMES AND GASES can be dangerous. • Keep your head out of fume[...]

  • Page 15

    B-3 OPERA TION B-3 POWER MIG 255C PRODUCT DESCRIPTION The POWER MIG™ 255C is a complete semiautomatic constant voltage DC arc welding machine built to meet NEMA specifications. It combines a constant voltage power source and a constant speed wire feeder with a microcomputer- based controller to form a reliable high-performance welding system. A s[...]

  • Page 16

    OPERA TION DESCRIPTION OF CONTROLS Power ON/OFF Switch — Place the lever in the "ON" position to energize the POWER MIG 255C. When the power is on, the red LED display lights illuminate. V oltage Control — This is a continuous control that gives full range adjustment of power source output voltage. It can be adjusted while welding ove[...]

  • Page 17

    B-5 OPERA TION B-5 POWER MIG 255C PROCEDURE FOR CHANGING DRIVE AND IDLE ROLL SETS 1. T urn off the power source. 2. Release the pressure on the idle roll by swinging the adjustable pressure arm down toward the back of the machine. Lift the cast idle roll assembly and allow it to sit in an upright position. 3. Remove the outside wire guide retaining[...]

  • Page 18

    B-6 OPERA TION B-6 POWER MIG 255C TO ST ART THE WELDER T urn the Power Switch switch to ON. This lights the red LED display lights. With the desired voltage and wire speed selected, operate the gun trigger for welder out- put and to energize the wire feed motor . FEEDING WIRE ELECTRODE When triggering, the electrode and drive mecha- nism are electr[...]

  • Page 19

    B-7 OPERA TION B-7 POWER MIG 255C 5. Loosen the socket head cap screw that holds the connector bar against the gun bushing. Important: Do not attempt to completely remove the socket head cap screw . 6. Remove the outer wire guide, and push the gun bushing out of the wire drive. Because of the pre- cision fit, light tapping may be required to remove[...]

  • Page 20

    B-8 OPERA TION B-8 POWER MIG 255C SETTING RUN-IN SPEED ON ST AN- DARD POWER MIG FEEDER F AST OR SLOW RUN-IN MODE SELECTION, (When Timer Option is not installed) The POWER MIG 255C is factory set for fast run-in mode where the wire feed will accelerate directly to the preset wire feed speed when the gun trigger is closed. Slow run-in mode may also b[...]

  • Page 21

    B-9 OPERA TION B-9 When using an open arc process, it is necessary to use correct eye, head, and body protection. 8. Position electrode over joint. End of electrode may be lightly touching the work. 9. Lower welding helmet, close gun trigger , and begin welding. Hold the gun so the contact tip to work dis- tance is about 3/8" (10 mm) [3/4"[...]

  • Page 22

    B-10 OPERA TION B-10 WELDING THERMAL OVERLOAD PROTECTION The POWER MIG 255C has built-in protective thermostats that respond to excessive temperature. They open the wire feed and welder output circuits if the machine exceeds the maximum safe operating temperature because of a frequent overload, or high ambient temperature plus overload. The thermos[...]

  • Page 23

    SECTION C ACCESSORIES SECTION C POWER MIG 255C T ABLE OF CONTENTS -ACCESSORIES SECTION- Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section C Drive Roll Kits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [...]

  • Page 24

    C-2 ACCESSORIES C-2 POWER MIG 255C DRIVE ROLL KITS Refer to T able C.1 for various drive roll kits that are available for the POWER MIG. All items in Bold are supplied standard with the POWER MIG. T ABLE C.1 — A V AILABLE DRIVE ROLL KITS. 3/64" (1.2 mm) ALUMINUM FEEDING KIT (K1703-1) This kit helps push feeding aluminum through standard mach[...]

  • Page 25

    C-3 ACCESSORIES C-3 POWER MIG 255C OPERA TING INSTRUCTIONS FOR TIMER KIT If the optional T imer Kit (K1701-1) is installed, select the desired mode with the selector switch: A. Normal Welding mode provides weld power only while the trigger switch is depressed. This is the same operation as when the T imer Kit is not installed. B. 4-Step T rigger in[...]

  • Page 26

    C-4 ACCESSORIES C-4 POWER MIG 255C Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC MAKING A WELD WITH THE PRINCE XL SPOOL GUN The POWER MIG control circuitry is designed to sense either the spool gun or (built in) wire feeder [...]

  • Page 27

    C-5 ACCESSORIES C-5 Closing either gun trigger will cause the electrode of both guns to be electrically "HOT". Be sure unused gun is positioned so electrode or tip will not contact metal case or other metal common to work. ----------------------------------------------------------------------------- 1. Pulling the trigger for the built-in[...]

  • Page 28

    C-6 NOTES POWER MIG 255 C-6 Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC[...]

  • Page 29

    SECTION D MAINTENANCE SECTION D POWER MIG 255C T ABLE OF CONTENTS -MAINTENANCE SECTION- Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section D Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .[...]

  • Page 30

    D-2 MAINTENANCE D-2 POWER MIG 255C SAFETY PRECAUTIONS • Have a qualified electrician do the maintenance and troubleshooting work. • Disconnect the input power off using the disconnect switch at the main input supply before working inside machine. • Unplug the power cable if it is connected to a receptacle. ------------------------------------[...]

  • Page 31

    D-3 MAINTENANCE D-3 POWER MIG 255C Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC LINER REMOV AL, INST ALLA TION AND TRIMMING INSTRUCTIONS FOR MAGNUM 250L NOTE: The variation in cable lengths prevents the interchangeability o[...]

  • Page 32

    D-4 MAINTENANCE D-4 POWER MIG 255C Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC T ABLE D.2 ACCESSORIES AND EXPENDABLE REPLACE- MENT P ARTS FOR MAGNUM 250L GUN AND CABLE ASSEMBLIES English Metric Description Part No. Size Si[...]

  • Page 33

    NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion SECTION E THEOR Y OF OPERA TION POWER MIG 255C SECTION E T ABLE OF CONTENTS -THEOR Y OF OPERA TION SECTION- Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section E Input Line V[...]

  • Page 34

    E-2 THEOR Y OF OPERA TION POWER MIG 255C E-2 INPUT LINE VOL T AGE AND MAIN TRANSFORMER The desired single phase input power is connected to the POWER MIG 255C through a line switch located on the front panel. A reconnect panel allows the user to configure the machine for the desired input voltage. This AC input voltage is applied to the primary of [...]

  • Page 35

    E-3 THEOR Y OF OPERA TION POWER MIG 255C E-3 OUTPUT RECTIFICA TION AND FEEDBACK CONTROL The AC output from the main transformer secondary weld winding is rectified and controlled through the SCR rectifier assembly . Output voltage and current are sensed at the shunt and output terminals and are fed back to the control board. The control board compa[...]

  • Page 36

    E-4 THEOR Y OF OPERA TION POWER MIG 255C E-4 CONST ANT VOL T AGE OUTPUT The controlled DC output from the SCR rectifier assembly is supplied to the power factor enhancement choke which limits the rate at which the supply current rises through the capacitors. The DC output from the NOTE: Unshaded areas of Block Logic Diagram are the subject of discu[...]

  • Page 37

    E-5 THEOR Y OF OPERA TION POWER MIG 255C E-5 WIRE DRIVE MOT OR AND FEEDBACK The wire drive motor is controlled by the control board. A motor speed feedback signal is generated at the motor tach and sent to the control board. The control board compares this feedback signal with the com- mands set forth by the Wire Speed Control poten- tiometer and s[...]

  • Page 38

    E-6 THEOR Y OF OPERA TION POWER MIG 255C E-6 THERMAL AND OVERLOAD PROTECTION The POWER MIG 255C has built-in protective ther- mostats that respond to excessive temperatures. One is located on the output choke. The other thermostat is located on the SCR heat sink assembly . They open the wire feed and welder output circuits if the machine exceeds th[...]

  • Page 39

    E-7 THEOR Y OF OPERA TION POWER MIG 255C E-7 SCR OPERA TION A silicon controlled rectifier (SCR) is a three terminal device used to control rather large currents to a load. An SCR acts very much like a switch. See Figure E.6 for a graphical representation of SCR operation. When a gate signal is applied to the SCR it is turned ON and there is curren[...]

  • Page 40

    E-8 NOTES POWER MIG 255C E-8 Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC[...]

  • Page 41

    F-1 TROUBLESHOOTING AND REP AIR F-1 POWER MIG 255C T ABLE OF CONTENTS -TROUBLESHOOTING AND REP AIR SECTION- T roubleshooting and Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section F How to Use T roubleshooting Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [...]

  • Page 42

    F-2 TROUBLESHOOTING AND REP AIR POWER MIG 255C F-2 This T roubleshooting Guide is provided to help you locate and repair possible machine malfunctions. Simply follow the three-step procedure listed below . Step 1. LOCA TE PROBLEM (SYMPTOM). Look under the column labeled “PROBLEM (SYMPTOMS)”. This column describes pos- sible symptoms that the ma[...]

  • Page 43

    POWER MIG 255C Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC TROUBLESHOOTING & REP AIR F-3 F-3 Sometimes machine failures appear to be due to PC board failures. These problems can sometimes be traced to poor electrical c[...]

  • Page 44

    F-4 TROUBLESHOOTING AND REP AIR F-4 POWER MIG 255C TROUBLESHOOTING GUIDE Observe all Safety Guidelines detailed throughout this manual. PROBLEMS (SYMPTOMS) POSSIBLE AREAS OF MISADJUSTMENT(S) RECOMMENDED COURSE OF ACTION Major Physical or Electrical Damage is Evident Machine is dead — no open circuit voltage output and no wire feed when gun trigge[...]

  • Page 45

    F-5 TROUBLESHOOTING AND REP AIR F-5 POWER MIG 255C Observe all Safety Guidelines detailed throughout this manual. PROBLEMS (SYMPTOMS) POSSIBLE AREAS OF MISADJUSTMENT(S) RECOMMENDED COURSE OF ACTION No open circuit voltage output but wire feeds normally when gun trig- ger is pulled. Wire feeds but welding output is low causing wire to “stub”. We[...]

  • Page 46

    F-6 TROUBLESHOOTING AND REP AIR F-6 POWER MIG 255C Observe all Safety Guidelines detailed throughout this manual. PROBLEMS (SYMPTOMS) POSSIBLE AREAS OF MISADJUSTMENT(S) RECOMMENDED COURSE OF ACTION The output voltage and wire feed is present continuously or pulsing when gun trigger is NOT activated. The output voltage is present contin- uously when[...]

  • Page 47

    F-7 TROUBLESHOOTING AND REP AIR F-7 POWER MIG 255C Observe all Safety Guidelines detailed throughout this manual. PROBLEMS (SYMPTOMS) POSSIBLE AREAS OF MISADJUSTMENT(S) RECOMMENDED COURSE OF ACTION No control of arc voltage. Wire feed- ing is normal. There is no gas flow when gun trig- ger is pulled. Wire feeds and weld voltage is present. The mach[...]

  • Page 48

    F-8 TROUBLESHOOTING AND REP AIR F-8 POWER MIG 255C Observe all Safety Guidelines detailed throughout this manual. PROBLEMS (SYMPTOMS) POSSIBLE AREAS OF MISADJUSTMENT(S) RECOMMENDED COURSE OF ACTION No control of wire feed speed. Other machine functions are normal There is no wire feed when gun trig- ger is pulled. Normal open circuit voltage is pre[...]

  • Page 49

    F-9 TROUBLESHOOTING AND REP AIR F-9 POWER MIG 255C Observe all Safety Guidelines detailed throughout this manual. CAUTION If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely , contact the Lincoln Electric Service Department for technical troubleshooting assistance before you proceed. Call 1-[...]

  • Page 50

    F-10 TROUBLESHOOTING AND REP AIR F-10 POWER MIG 255C Observe all Safety Guidelines detailed throughout this manual. PROBLEMS (SYMPTOMS) POSSIBLE AREAS OF MISADJUSTMENT(S) RECOMMENDED COURSE OF ACTION The contact tip seizes in the gas diffuser . The welding arc is variable and sluggish. The arc striking is poor . 1. The tip being over heated due to [...]

  • Page 51

    F-11 TROUBLESHOOTING AND REP AIR F-11 MAIN TRANSFORMER TEST Service and repair should only be performed by Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in dan- ger to the technician or machine operator and will invalidate your factory war- ranty . For your safety and to avoid electrical sho[...]

  • Page 52

    F-12 TROUBLESHOOTING AND REP AIR F-12 POWER MIG 255C 4. Locate plug J6 on the control PC board. See Figure F .1. NOTE: The location of plugs may vary depending on the machine code. 5. Locate the following leads on plug J6 on the control PC board: TEST PROCEDURE The ON/OFF POWER SWITCH will be “hot” during these tests. --------------------------[...]

  • Page 53

    F-13 TROUBLESHOOTING AND REP AIR F-13 POWER MIG 255C 11 .T urn the machine ON. 12. Make the following voltage tests at plug J5. a. T urn the machine OFF between each test. b. Carefully insert the meter probes into the back of each Molex plug pin cavity to perform the test. c. If the voltage tested is incorrect, check for loose or broken leads betwe[...]

  • Page 54

    F-14 TROUBLESHOOTING AND REP AIR F-14 POWER MIG 255C d. If ALL the voltages tested are incor- rect or missing, go to step 16. 17. T est for correct nameplate input voltage between the H1 lead at the ON/OFF POWER SWITCH to H2 or H3 (H5 if connected for 575 V AC) at the reconnect panel. V oltage tested will vary depending on input voltage connection.[...]

  • Page 55

    F-15 TROUBLESHOOTING AND REP AIR F-15 RECTIFIER DIODE BRIDGE TEST Service and repair should only be performed by Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in dan- ger to the technician or machine operator and will invalidate your factory war- ranty . For your safety and to avoid electric[...]

  • Page 56

    F-16 TROUBLESHOOTING AND REP AIR F-16 POWER MIG 255C Leads #208, #209, and #354 are con- nected to the rectifier diode bridge (D2). See Figure F .2. Lead #206 is connect- ed at the output shunt. See the wiring diagram. 5. Connect main input power to the machine. TEST PROCEDURE 1. Disconnect the main AC input power to the machine. 2. Remove the case[...]

  • Page 57

    F-17 TROUBLESHOOTING AND REP AIR F-17 POWER MIG 255C 9. Make the following voltage test: a. T urn the machine OFF between each test. b. Carefully connect the meter probes to the exposed lead connections. c. T urn the machine ON to conduct the voltage test. 10. If the DC voltage tested is incorrect or missing, and the AC voltages are cor- rect, the [...]

  • Page 58

    F-18 NOTES POWER MIG 255C F-18 Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC[...]

  • Page 59

    F-19 TROUBLESHOOTING AND REP AIR F-19 ST A TIC SCR RECTIFIER ASSEMBL Y TEST Service and repair should only be performed by Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in dan- ger to the technician or machine operator and will invalidate your factory war- ranty . For your safety and to avoi[...]

  • Page 60

    F-20 TROUBLESHOOTING AND REP AIR F-20 POWER MIG 255C 4. V erify that the capacitors have completely discharged with a volt- ohmmeter . 5. Disconnect plugs J6 and J5 from the control board . This electrically isolates the SCR bridge assembly . See Figure F .3. TEST PROCEDURE 1. Disconnect main AC input power to the machine. 2. Remove the case top an[...]

  • Page 61

    F-21 TROUBLESHOOTING AND REP AIR F-21 POWER MIG 255C FIGURE F .5 — SCR 1 TEST POINTS. 9. T est 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 in[...]

  • Page 62

    F-22 NOTES POWER MIG 255C F-22 Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC[...]

  • Page 63

    F-23 TROUBLESHOOTING AND REP AIR F-23 ACTIVE SCR RECTIFIER ASSEMBL Y TEST Service and repair should only be performed by Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in dan- ger to the technician or machine operator and will invalidate your factory war- ranty . For your safety and to avoid [...]

  • Page 64

    F-24 TROUBLESHOOTING AND REP AIR F-24 POWER MIG 255C 4.V erify that the capacitors have completely discharged with a volt-ohmmeter . 5. Disconnect plugs J6 and J5 control board. This electrically isolates the SCR bridge assembly . See Figure F .6. TEST PROCEDURE 1. Disconnect main AC input power to the machine. 2. Remove the case top and side panel[...]

  • Page 65

    8. Use a commercial SCR tester or con- struct the tester circuit shown in Figure F .8. One 6-volt lantern battery can be used. R1 and R2 resistor values are ± 10%. Set voltmeter scale low , at approximately 0-5 volts or 5-10 volts. a. T est the voltage level of the battery . Short leads (A) and (C). Close switch SW-1. Battery voltage should be 4.5[...]

  • Page 66

    F-26 TROUBLESHOOTING AND REP AIR F-26 POWER MIG 255C 15. Reconnect the tester leads. See Figure F .8. a. Connect tester lead (A) to the cathode. b. Connect tester lead (C) to the anode. c. Disconnect test lead (G) from the gate. 16. Close switch SW -1. 17. Read meter for zero voltage. a. If the voltage is zero, the SCR is functioning. b. If the vol[...]

  • Page 67

    F-27 TROUBLESHOOTING AND REP AIR F-27 WIRE DRIVE MOTOR AND T ACHOMETER FEEDBACK TEST Service and repair should only be performed by Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in dan- ger to the technician or machine operator and will invalidate your factory war- ranty . For your safety an[...]

  • Page 68

    F-28 TROUBLESHOOTING AND REP AIR F-28 POWER MIG 255C 3. Locate plug J1 on the control PC board. See Figure F .9. 4. Locate the following leads on plug J1: 5. Connect the main power to the machine. TEST PROCEDURE NOTE: POLARITY MUST BE OBSERVED FOR THESE TESTS. T est for Correct Wire Drive Motor Armature V oltage 1. Disconnect main input power to th[...]

  • Page 69

    F-29 TROUBLESHOOTING AND REP AIR F-29 POWER MIG 255C 2. Locate plug J1 on the control PC board. See Figure F .9. 3. Locate the following leads on Plug J1: 4. Connect main input power to the machine. 5. Make the following voltage tests: a. T urn the machine OFF between each test. b. Carefully insert the meter probes into the back of each Molex plug [...]

  • Page 70

    F-30 TROUBLESHOOTING AND REP AIR F-30 POWER MIG 255C gun trigger to conduct the voltage test. 6. If the 1.5 to 3.5 VDC is present, the tachometer circuit is sending the cor- rect feedback signal to the Control PC Board. 7. If the 1.5 to 3.5 VDC is not present or not correct, the Control PC Board is not receiving the proper feedback voltage from the[...]

  • Page 71

    F-31 TROUBLESHOOTING AND REP AIR POWER MIG 255C F-31 0 VOLTS 20.0 V 2.5 ms This is a typical DC output voltage waveform generated from a properly operating machine. Note that each vertical division represents 20 volts and that each horizontal division represents 2.5 milliseconds in time. NOTE: Scope probes connected at machine output terminals: (+)[...]

  • Page 72

    F-32 TROUBLESHOOTING AND REP AIR POWER MIG 255C F-32 0 VOLTS 20.0 V 5 ms MACHINE LOADED TO 250 AMPS A T 26 VDC TYPICAL OUTPUT VOL T AGE W A VEFORM - MACHINE LOADED This is a typical DC output voltage waveform generated from a properly operating machine. Note that each vertical division represents 20 volts and that each horizontal division represent[...]

  • Page 73

    F-33 TROUBLESHOOTING AND REP AIR POWER MIG 255C F-33 0 VOLTS 20.0 V 5 ms MACHINE LOADED TO 220 AMPS A T 22 VDC ABNORMAL OUTPUT VOL T AGE W A VEFORM - MACHINE LOADED ONE OUTPUT SCR NOT FUNCTIONING This is NOT a typical DC output voltage waveform. One output SCR is not function- ing. Note the increased ripple content. One SCR gate was disconnected to[...]

  • Page 74

    F-34 TROUBLESHOOTING AND REP AIR POWER MIG 255C F-34 0 VOLTS 20.0 V 5 ms ABNORMAL OPEN CIRCUIT VOL T AGE OUTPUT CAP ACITOR BANK NOT FUNCTIONING This is NOT the typical DC output voltage waveform. The output capacitors are not functioning. Note the lack of “filtering” in the output waveform. The output capacitor bank was disconnected. Each verti[...]

  • Page 75

    F-35 TROUBLESHOOTING AND REP AIR POWER MIG 255C F-35 0 VOLTS 2.00 V 5 ms TYPICAL SCR GA TE VOL T AGE W A VEFORM This is a typical SCR gate pulse voltage waveform. The machine was in an open circuit condition (no load) and operating properly . Note that each vertical division represents 2 volts and each horizontal division represents 5 milliseconds [...]

  • Page 76

    F-36 NOTES POWER MIG 255C F-36 Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC[...]

  • Page 77

    F-37 TROUBLESHOOTING AND REP AIR F-37 CONTROL PC BOARD REMOV AL AND REPLACEMENT Service and repair should only be performed by Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in dan- ger to the technician or machine operator and will invalidate your factory war- ranty . For your safety and to [...]

  • Page 78

    F-38 TROUBLESHOOTING AND REP AIR F-38 POWER MIG 255C REMOV AL AND REPLACEMENT PROCEDURE 1. Disconnect main input power the machine. 2. Open the side panels and remove the tool tray using a 5/16 in. nutdriver . 3. Disconnect all wiring harness plugs and Molex plugs connected to the control board. See Figure F .10. FIGURE F .10 — WIRING HARNESS AND[...]

  • Page 79

    F-39 TROUBLESHOOTING AND REP AIR F-39 POWER MIG 255C 7. When re-installing the control PC board carefully secure board to mounting standoffs. 8. Install all plug connectors previously removed from the control PC board. 9. Install the tool tray and close the side panels. 4. Ensure a static electricity grounding strap is used before handling the con-[...]

  • Page 80

    F-40 NOTES POWER MIG 255C F-40 Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC[...]

  • Page 81

    F-41 TROUBLESHOOTING AND REP AIR F-41 WIRE DRIVE ASSEMBL Y REMOV AL AND REPLACEMENT Service and repair should only be performed by Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in dan- ger to the technician or machine operator and will invalidate your factory war- ranty . For your safety and[...]

  • Page 82

    F-42 TROUBLESHOOTING AND REP AIR F-42 POWER MIG 255C 6B Set Screw 7 Knurled Knob 8 Gun Adapter Assembly 9A Feedplate Cover 9B 1/4-20 x .50 HHCS 9C Lock Washer 10 Drive Roll Shaft Assembly 11 Drive Hub Retainer 12 Inner Wire Guide (.035/.045) 13 Drive Roll (.035/.045) 14 Outer Guide Assembly 15 Wire Drive Compartment 16 #10-24 HLN - Nylon Insert 17A[...]

  • Page 83

    F-43 TROUBLESHOOTING AND REP AIR F-43 POWER MIG 255C 11 . Swing the idle arm up and away from the wire drive assembly . 12. Use a screwdriver and remove the round head screw , lock washer , and flat washer securing the molded drive roll shaft assembly to the wire drive assem- bly . 13. Remove the molded drive roll shaft assembly and the rest of the[...]

  • Page 84

    F-44 NOTES POWER MIG 255C F-44 Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC[...]

  • Page 85

    F-45 TROUBLESHOOTING AND REP AIR F-45 SCR OUTPUT RECTIFIER REMOV AL AND REPLACEMENT Service and repair should only be performed by Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in dan- ger to the technician or machine operator and will invalidate your factory war- ranty . For your safety and[...]

  • Page 86

    F-46 TROUBLESHOOTING AND REP AIR F-46 POWER MIG 255C 3. Disconnect lead #204 and heavy alu- minum choke lead from the middle heat sink with a 1/2 in. socket wrench and 1/2 in. open end wrench. See Figure F .14. 4. Remove the diode lead from the nega- tive capacitor band buss bar on the right side of the machine using a 1/2 in. socket and 3/8 in. op[...]

  • Page 87

    F-47 TROUBLESHOOTING AND REP AIR F-47 POWER MIG 255C 8. Clear the leads and carefully remove the SCR rectifier assembly . NOTE: When installing the SCR rectifier assembly , apply a thin coating of Dow Corning #340 compound to the electrical connections. 9. Unplug leads 320 and 320B from the SCR heat sink thermostat on the right side at the SCR asse[...]

  • Page 88

    F-48 NOTES POWER MIG 255C F-48 Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC[...]

  • Page 89

    F-49 TROUBLESHOOTING AND REP AIR F-49 CAP ACITOR BANK REMOV AL AND REPLACEMENT Service and repair should only be performed by Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in dan- ger to the technician or machine operator and will invalidate your factory war- ranty . For your safety and to a[...]

  • Page 90

    F-50 TROUBLESHOOTING AND REP AIR F-50 POWER MIG 255C tive capacitor bank buss bar using a 1/2 in. open end wrench. 6. Remove the choke lead and lead 204B from the positive capacitor bank buss bar using two 1/2 in. open end wrench- es. 7. Remove the power factor enhancement choke lead from the positive capacitor buss bar using two 1/2 in. open end w[...]

  • Page 91

    F-51 TROUBLESHOOTING AND REP AIR F-51 MAIN TRANSFORMER AND OUTPUT CHOKE REMOV AL AND REPLACEMENT Service and repair should only be performed by Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in dan- ger to the technician or machine operator and will invalidate your factory war- ranty . For yo[...]

  • Page 92

    F-52 TROUBLESHOOTING AND REP AIR F-52 POWER MIG 255C 6. Remove the two transformer secondary leads X2 and X3 (braided copper strap) from the negative capacitor bank buss bar using two 1/2 in. open end wrench- es. 7. Disconnect and label all transformer leads from the reconnect panel using a 3/8 in. open end wrench. 8. Disconnect and label all leads[...]

  • Page 93

    TROUBLESHOOTING AND REP AIR 11 . Unplug and label leads X5, X6, X7, X8, and X9. These leads have connectors near the trans- former which can be disconnected. 12. Disconnect the output choke lead from the posi- tive capacitor bank buss using two 1/2 in. open end wrenches. 13. Remove the other output choke lead from the positive output terminal using[...]

  • Page 94

    NOTES POWER MIG 255C F-54 F-54 Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC[...]

  • Page 95

    F-55 TROUBLESHOOTING AND REP AIR F-55 F AN MOTOR ASSEMBL Y REMOV AL AND REPLACEMENT Service and repair should only be performed by Lincoln Electric factory trained personnel. Unauthorized repairs performed on this equipment may result in dan- ger to the technician or machine operator and will invalidate your factory war- ranty . For your safety and[...]

  • Page 96

    F-56 TROUBLESHOOTING AND REP AIR F-56 POWER MIG 255C a. Loosen and remove the two nuts and lock washers from the motor mounting bracket using a 1 1/32 in. open end wrench. b. When the motor is free from the mounting bracket, slide the motor from the POWER MIG unit. 5. Install the replacement motor in the reverse order of removal. 6. Install the fan[...]

  • Page 97

    F-57 TROUBLESHOOTING AND REP AIR POWER MIG 255C F-57 INPUT IDLE AMPS AND W A TTS WIRE SPEED RANGE OPEN CIRCUIT VOL T AGE RETEST AFTER REP AIR Maximum Idle W atts Maximum Idle Amps Input V olts/Hertz 400 7.0 230/60 50 - 700 IPM (1.27 - 17.8 m/minute) 35-40 VDC Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC Re[...]

  • Page 98

    NOTES POWER MIG 255C Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC[...]

  • Page 99

    Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC POWER MIG 255C Section G-1 Section G-1 T ABLE OF CONTENTS - ELECTRICAL DIAGRAMS SECTION - Electrical Diagrams ...............................................................................................Section G Wiring Diagram - Entire Machine - Code 1 1 192 - (L[...]

  • Page 100

    ELECTRICAL DIAGRAMS G-2 POWER MIG 255C WIRING DIAGRAM - ENTIRE MACHINE - CODE 1 1 192 (L12464) G-2 NOTE: This diagram is for reference only . It may not be accurate for all machines covered by this manual. The wiring diagram specific to your code is pasted inside one of the enclosure panels of your machine. Return to Section TOC Return to Section T[...]

  • Page 101

    ELECTRICAL DIAGRAMS G-3 POWER MIG 255C WIRING DIAGRAM - ENTIRE MACHINE CODE 1 1218 (L12506) G-3 NOTE: This diagram is for reference only . It may not be accurate for all machines covered by this manual. The wiring diagram specific to your code is pasted inside one of the enclosure panels of your machine. Return to Section TOC Return to Section TOC [...]

  • Page 102

    Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC ELECTRICAL DIAGRAMS G-4 POWER MIG 255C SCHEMA TIC - ENTIRE MACHINE - (G4752) G-4 NOTE: This diagram is for reference only . It may not be accurate for all machines covered by thi[...]

  • Page 103

    ELECTRICAL DIAGRAMS G-5 POWER MIG 255C SCHEMA TIC - CONTROL PC BOARD - (G4823-2D1 SHEET 1) G-5 NOTE: This diagram is for reference only . It may not be accurate for all machines covered by this manual. Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC Return to Master TOC Return to Master TOC Return to Master T[...]

  • Page 104

    ELECTRICAL DIAGRAMS G-6 POWER MIG 255C SCHEMA TIC - CONTROL PC BOARD - (G4823-2D1 SHEET 2) G-6 NOTE: This diagram is for reference only . It may not be accurate for all machines covered by this manual. Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC Return to Master TOC Return to Master TOC Return to Master T[...]

  • Page 105

    ELECTRICAL DIAGRAMS G-7 POWER MIG 255C SCHEMA TIC - CONTROL PC BOARD - (G4823-2D1 SHEET 3) G-7 NOTE: This diagram is for reference only . It may not be accurate for all machines covered by this manual. Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC Return to Master TOC Return to Master TOC Return to Master T[...]

  • Page 106

    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 available from Lincoln Electric. This information is pro- vided for reference only . Lincoln Electric discourages board level troub[...]

  • Page 107

    ELECTRICAL DIAGRAMS G-9 POWER MIG 255C SCHEMA TIC - DISPLA Y PC BOARD (L10951) 500 475 R10 DISP2 2 1 4 9 5 10 7 6 8 3 LED3 X5 12 13 J10 4 DISP3 2 1 4 9 5 10 7 6 8 3 14 3 Rx Vdd d BANK1 g DATA OUT f CLOCK MC14489 DATA IN h Vss BANK3 BANK4 BANK2 a /ENABLE e c BANK5 b X3 18 9 17 6 5 2 10 19 8 1 13 12 16 20 11 15 4 7 1.50K R11 J10 6 X5 2 1 500 500 LATC[...]

  • Page 108

    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 available from Lincoln Electric. This information is pro- vided for reference only . Lincoln Electric discourages board level troub[...]

  • Page 109

    SVM ERROR REPORTING FORM We need to know if there are errors in our manuals. We also value any suggestions as to additional tests or procedures that would make this SVM a better tool for you. If you discover new or different “Problems or Symptoms” that are not covered in the three col- umn troubleshooting chart, please share this information wi[...]