Lincoln Electric Classic 300 MP Service Manual
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Lincoln Electric Classic 300 MP Service Manual

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Classic ® 300 MP
For use with machines having Code Numbers:
Classic 300 MP: 12546
SERVICE MANUAL
SVM273
| Issue D ate 17-Feb
© Lincoln Global, Inc. All Rights Reserved.

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  • Page 1 Classic ® 300 MP For use with machines having Code Numbers: Classic 300 MP: 12546 SERVICE MANUAL SVM273 | Issue D ate 17-Feb © Lincoln Global, Inc. All Rights Reserved.
  • Page 2 THANK YOU FOR SELECTING A QUALITY PRODUCT BY KEEP YOUR HEAD OUT OF THE FUMES. DON’T get too close to the arc. LINCOLN ELEC TRIC. Use corrective lenses if necessary to stay a reasonable distance away from the arc. READ and obey the Safety Data PLEASE EXAMINE CARTON AND EQUIPMENT FOR Sheet (SDS) and the warning label DAMAGE IMMEDIATELY...
  • Page 3 MAGNETIC FIELDS MAY W117.2-1974. A Free copy of “Arc Welding Safety” booklet BE DANGEROUS E205 is available from the Lincoln Electric Company, 22801 St. Clair Avenue, Cleveland, Ohio 44117-1199. 2.a. Electric current flowing through any conductor BE SURE THAT ALL INSTALLATION, OPERATION, causes localized Electric and Magnetic Fields (EMF).
  • Page 4 S FETY ELECTRIC SHOCK ARC RAYS CAN BURN. CAN KILL. 3.a. The electrode and work (or ground) circuits are 4.a. Use a shield with the proper filter and cover plates to protect your electrically “hot” when the welder is on. Do eyes from sparks and the rays of the arc when welding or not touch these “hot”...
  • Page 5 S FETY WELDING AND CUTTING CYLINDER MAY EXPLODE IF SPARKS CAN CAUSE DAMAGED. FIRE OR EXPLOSION. 7.a. Use only compressed gas cylinders containing the correct shielding gas for the process used 6.a. Remove fire hazards from the welding area. If and properly operating regulators designed for this is not possible, cover them to prevent the welding sparks the gas and pressure used.

  • Page 6: Table Of Contents

    LINCOLN ELECTRIC Classic® 300 MP Service Manual Classic® 300 MP Service Manual Last update: 2017/02/01 CLASSIC® 300 MP ............................. 1 Service Manual................................1 Theory of Operation ..............................3 ENGINE STARTING, PROTECTION AND ENGINE CONTROL UNIT (ECU) ............3 ENGINE SPEED CONTROL ......................... 4 EXCITER ALTERNATOR ..........................
  • Page 7 LINCOLN ELECTRIC Classic® 300 MP Service Manual OUTPUT CHOKE TEST PROCEDURE ......................39 EXCITER FIELD DIODE TEST PROCEDURE ....................41 EXCITER BRUSH AND SLIP RING SERVICE PROCEDURE ................44 WELDING GENERATOR BRUSH AND COMMUTATOR INSPECTION AND SERVICE........47 ROCKER ADJUSTMENT PROCEDURE ....................... 50 EXCITER ROTOR VOLTAGE TEST PROCEDURE ..................

  • Page 8: Theory Of Operation

    LINCOLN ELECTRIC Classic® 300 MP Service Manual Theory of Operation Figure E.1 – Engine starting, protection and engine control unit (ECU) Engine Starting, Protection And Engine Control Unit (ECU) The 12 VDC battery circuit is connected directly to the engine starter solenoid, the engine alternator, the glow plug switch and the ignition switch.

  • Page 9: Engine Speed Control

    LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure E.2 – Engine speed control Engine Speed Control The ECU monitors the engine speed and during high RPM conditions keeps the engine at a steady 1800 RPM regardless of the welding or auxiliary power loads. If the idle switch is set to the auto position the ECU will, under no load conditions, regulate the engine speed to 1440 RPM.

  • Page 10: Exciter Alternator

    LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure E.3 – Exciter alternator Exciter Alternator The exciter alternator is attached to the end of the welding generator frame. The exciter is responsible for producing the auxiliary outputs and power for the control board. The alternator rotor, which is a revolving field, requires a DC voltage to energize (flash) it.

  • Page 11: Dc Generator

    LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure E.4 – DC generator DC Generator The two shunt windings are powered by the control board. When a DC voltage is applied to these two windings a magnetic field is established with two distinct poles.

  • Page 12: Open Circuit And Voltage Control

    LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure E.5 – Open circuit and voltage control Open Circuit And Voltage Control The control board receives feedback voltage information from the DC generator brushes. The control board monitors this feedback information and compares it to the user commands set forth from the Fine Current and Open Circuit Voltage potentiometer.

  • Page 13: Welding Current Control

    LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure E.6 – Welding current control Welding Current Control The coarse current control is handled by a selector switch that selects different portions of the series field coil. The series field is between the negative brushes and the constant current negative output stud. The current passing through the series coils creates a field that opposes the shunt field.

  • Page 14: Constant Voltage Cv Box

    LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure E.7 – Constant voltage CV box Constant Voltage CV Box The CV box contains two contactors and several filter capacitors. When the mode switch is placed into the CV mode the CV box is activated. One of the contactors is energized and brings the filter capacitors into the CV welding circuit to provide a more constant DC output voltage for wire welding.

  • Page 15: Dc Generator Machines

    LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure E.8 – DC generator machines DC Generator Machines The armature winding of a DC generator is located on the rotating member. Current is conducted from it by means of carbon brushes. The field winding is located in the stator, which is stationary and is excited by direct current.

  • Page 16: Troubleshooting & Repair

    Troubleshooting & Repair HOW TO USE TROUBLESHOOTING GUIDE Service and repair should be performed by only Lincoln Electric Factory Trained Personnel. Unauthorized repairs performed on this equipment may result in danger to the technician and machine operator and will invalidate your factory warranty. For your safety and to avoid Electrical Shock, please observe all safety notes and precautions detailed throughout this manual.

  • Page 17: Pc Board Troubleshooting Procedures

    ELECTRIC SHOCK can kill. remove them until installation is complete. • If you return a PC board to The Lincoln Electric Company • Have an electrician install and service this for credit, it must be in the static-shielding bag. This will equipment.

  • Page 18: Troubleshooting Guide

    AC auxiliary power Test Procedure. receptacles. If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 19 (ECU Test). operating correctly. If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 20 NOT be grounded to the stator lamination. If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 21 Check for grounds and/or shorts. If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 22 10. Perform the Control Board Test Procedure. If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 23 2. Perform the CV Box Test Procedure. If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 24 1. Perform the Engine charge. Alternator Test Procedure. If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 25 4. Perform the Rocker Adjustment Procedure. If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.

  • Page 26: Test Procedures

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 27 LINCOLN ELECTRIC Classic® 300 MP Service Manual 5. Lower the door panels. 6. Place the exhaust pipe onto the machine. 7. Using a 1/2” nutdriver, tighten the clamp securing the exhaust pipe to the machine. 8. Carefully attach the fuel gasket and fuel cap to the machine.
  • Page 28 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.2 – Case cover mounting hardware locations...

  • Page 29: Engine Alternator Test Procedure

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 30 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.3 – Engine alternator location Figure F.4 – Engine alternator lead locations...

  • Page 31: Engine Fuel System Voltage Test Procedure (Ecu Test)

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 32 LINCOLN ELECTRIC Classic® 300 MP Service Manual CHECK THAT “WK” STUD IS OPEN WHEN ENGINE IS NOT RUNNING. LEAD TO WATER TEMPERATURE SWITCH MAY BE GROUNDED – CHECK. NOT ENABLED FOR LINCOLN LONG 1, SHORT 5 PRODUCTS. FAULTY RPM SENSOR – CHECK FOR 12 VOLTS 0 RPM IS DETECTED AND 12V IS ON SUPPLY LEAD TO RPM SENSOR FROM ECU.
  • Page 33 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.5 – Fuel / hour / LED gauge location Figure F.6 – Engine fault indicator location...

  • Page 34: Control Board Test Procedure

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 35 LINCOLN ELECTRIC Classic® 300 MP Service Manual Table F. 2 – LED flash codes DIAGNOSTIC LED FLASH CODES (LED TIED IN HARNESS AT CONTROL BOARD) LONG SHORT DESCRIPTION FLASH FLASH FIELD COIL SHORTED – FAULT CAN ONLY BE RESET BY RESTARTING WELDER.
  • Page 36 LINCOLN ELECTRIC Classic® 300 MP Service Manual FLASHING (LEAD 610) (LEAD 600) START-UP. SUPPLY TO SHUNT J1 PIN 1 J1 PIN 2 110 VDC ENGINE RUNNING. COILS (LEAD 612) (LEAD 602) ENGINE RUNNING. SUPPLY TO CR2 IN J2 PIN 5...
  • Page 37 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.8 – CV box mounting hardware location Figure F.9 – CV box mounting hardware location...

  • Page 38: Cv Box Test Procedure

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 39 LINCOLN ELECTRIC Classic® 300 MP Service Manual 11. If faulty, perform the Contactor CR2 Removal And Replacement Procedure. Contactor CR1: 12. Label and disconnect leads 633 and 634 from contactor CR1 quick-connects. See Figure F.11. See Wiring Diagram. 13. Using a volt/ohmmeter, measure the contacts resistance of contactor CR1. See Figure F.11. See Wiring Diagram.
  • Page 40 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.11 – CV box components and test point locations...

  • Page 41: Selector Switch Test Procedure

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 42 LINCOLN ELECTRIC Classic® 300 MP Service Manual Table F. 4 – Selector switch resistance tests SELECTOR SWITCH TEST POINT TEST POINT EXPECTED READING POSITION LESS THAN 1 OHM TERMINAL 1 (90-MIN) NEG TERMINAL SET TO 90-MIN POSITION (LOW RESISTANCE) LESS THAN 1 OHM...
  • Page 43 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.12 – Selector switch location Figure F.13 – Selector switch terminal locations...

  • Page 44: Output Choke Test Procedure

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 45 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.14 – Output choke location Figure F.15 – Output choke terminal locations...

  • Page 46: Exciter Field Diode Test Procedure

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 47 LINCOLN ELECTRIC Classic® 300 MP Service Manual Table F. 5 – Exciter Field Diode test points TEST POINT (POS) TEST POINT (NEG) EXPECTED READING TOP AC TERMINAL POSITIVE TERMINAL 0.2 VDC – 0.7 VDC BOTTOM AC TERMINAL POSITIVE TERMINAL 0.2 VDC – 0.7 VDC...
  • Page 48 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.17 – Exciter Field Diode location Figure F.18 – Exciter Field Diode terminal and locations...

  • Page 49: Exciter Brush And Slip Ring Service Procedure

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 50 LINCOLN ELECTRIC Classic® 300 MP Service Manual Cleaning slip rings 7. In the event that the slip rings have become dirty, discolored or mildly pitted, it will be necessary to clean them, using very fine emery cloth. Seating brushes 8. If brushes have been replaced, repositioned or are not making full contact with the slip rings, it will be necessary to re-seat them.
  • Page 51 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.20 – Exciter brush and slip ring locations...

  • Page 52: Welding Generator Brush And Commutator Inspection And Service

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 53 LINCOLN ELECTRIC Classic® 300 MP Service Manual screw. This screw should be tightened to a torque of 70 to 75 inch-lbs. Over tightening can destroy the rocker. • Perform the Test Procedure. • If the weld circuit is not grounded or shorted and poor brush quality or contamination is suspected, replace the brushes and seat them with a commutator stone or sand paper.
  • Page 54 LINCOLN ELECTRIC Classic® 300 MP Service Manual The brushes should be seated so that the face of each brush makes 95% minimum contact with the commutator. Lightly stone the commutator to seat the brushes. See caution note on commutator stone usage.

  • Page 55: Rocker Adjustment Procedure

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 56 LINCOLN ELECTRIC Classic® 300 MP Service Manual IMPORTANT: The following procedures should only be attempted if all the other systems have been thoroughly checked and are functioning normally. 6. A tachometer will be required for this phase of the test.

  • Page 57: Exciter Rotor Voltage Test Procedure

    Wiring Diagram TEST PROCEDURE 1. Turn off the engine on the Classic 300 MP machine. The engine should be at normal operating temperature for this test. If the machine is cold, the voltage readings may be slightly higher than specified.
  • Page 58 LINCOLN ELECTRIC Classic® 300 MP Service Manual 9. Be sure that there are no loads of any kind across any of the stator windings. The exciter winding should be the only stator winding connected at this time. Examine stator wiring for damage, pinched leads, chaffed insulation, etc.
  • Page 59 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.23 – Brush terminal location...

  • Page 60: Exciter Rotor Resistance And Ground Test

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 61 LINCOLN ELECTRIC Classic® 300 MP Service Manual NOTE: This test must be performed with a good quality analog type ohmmeter. Many digital meters will not provide stable or accurate resistance readings while the rotor is spinning. This test requires that the brushes and slip rings are clean, in good condition and are properly seated.
  • Page 62 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.25 – Slip ring and brush terminal locations...

  • Page 63: Exciter Flashing Voltage Test Procedure

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 64 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.26 – Exciter cover locations Figure F.27 – Brush terminal location...

  • Page 65: Exciter Stator Short Circuit & Ground Test Procedure

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 66 LINCOLN ELECTRIC Classic® 300 MP Service Manual 11. If any of these readings are less than 500,000 (500k) ohms, be certain that the windings are completely dry and check for grounded components or wiring that remain connected to the stator, such as circuit breakers, receptacles, etc.
  • Page 67 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.29 – Exciter stator test point locations...

  • Page 68: Weld Circuit Ground And Short Circuit Test Procedure

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 69 LINCOLN ELECTRIC Classic® 300 MP Service Manual 8. Test for a short circuit condition between the positive and negative circuits. 9. With the brushes still isolated as described above, check the resistance between the two of the weld terminals. The resistance should be very high, 500,000 (500k) Ohms minimum.

  • Page 70: Shunt Field Coil Resistance And Ground Test Procedure

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 71 LINCOLN ELECTRIC Classic® 300 MP Service Manual 9. If the resistance is low, check the lead wires connected to the shunt coils and the jumper lead wire connecting the two coils together. If these leads are in good condition and the low resistance is determined to be a defective coil.

  • Page 72: Shunt Field Circuit Voltage Test Procedure

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 73 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.32 – CV box mounting hardware location Figure F.33 – Fine current / OCV control knob location...

  • Page 74: Removal And Replacement Procedures

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 75 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.34 – Finger guard panel mounting screw locations Figure F.35 – Engine control unit connector location...
  • Page 76 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.36 – Engine control unit mounting hardware location...

  • Page 77: Control Board Removal And Replacement Procedure

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 78 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.37 – CV box mounting hardware location Figure F.38 – Control board plug locations...
  • Page 79 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.39 – Control board mounting screw locations...

  • Page 80: Contactor Cr1 Removal And Replacement Procedure

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 81 LINCOLN ELECTRIC Classic® 300 MP Service Manual 3. Using a 11/16” nutdriver, attach the four nuts (two for each lead) securing the heavy leads to the terminals on contactor CR1. See Wiring Diagram. 4. Connect the leads 633 and 634 to the quick connects of contactor CR1. See Wiring Diagram.
  • Page 82 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.41 – Contactor CR1 lead 633 and 634 locations Figure F.42 – Contactor CR1 lead and mounting hardware locations...

  • Page 83: Contactor Cr2 Removal And Replacement Procedure

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 84 LINCOLN ELECTRIC Classic® 300 MP Service Manual 4. Connect leads 630 and 631 to the top terminals of contactor CR2. See Wiring Diagram. 5. Using a 5/16” nutdriver, attach the thirteen screws securing the CV box support to the CV box base.
  • Page 85 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.44 – Contactor CR2 lead and terminal locations Figure F.45 – Contactor CR2 mounting screw locations...

  • Page 86: Selector Switch Removal And Replacement Procedure

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 87 LINCOLN ELECTRIC Classic® 300 MP Service Manual 5. Using a 1/2” open-end wrench and 1/2” nutdriver, attach the five nuts securing the heavy leads to terminals 1-5 of the selector switch. See Wiring Diagram. Case Cover Replacement Procedure. Perform the 7.

  • Page 88: Output Choke Removal And Replacement Procedure

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 89 LINCOLN ELECTRIC Classic® 300 MP Service Manual 4. Using a 9/16” nutdriver, attach the two bolts and nuts securing the output choke to the rear support assembly. 5. Using a 1/2” open-end wrench and a 1/2” nutdriver, attach the bolt and nut securing the output choke to the fuel tank rail.
  • Page 90 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.49 – Output choke mounting screw location Figure F.50 –Output choke terminal locations...

  • Page 91: Exciter Field Diode Removal And Replacement Procedure

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 92 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.51 – CV box mounting hardware location Figure F.52 – Exciter field diode lead locations...
  • Page 93 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.53 – Exciter field diode mounting hardware location...

  • Page 94: Fuel Tank Removal And Replacement Procedure

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 95 LINCOLN ELECTRIC Classic® 300 MP Service Manual 10. Using a 9/16” open-end wrench and a 9/16” nutdriver, remove the two nuts, bolts, lock washers and three flat washers (one set in the front and one set in the rear) securing the fuel tank to the fuel tank rail.
  • Page 96 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.55 – Fuel line connection location Figure F.56 – CV box mounting hardware location...
  • Page 97 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.57 – Fuel tank mounting hardware location...

  • Page 98: Exciter Brush Removal And Replacement Procedure

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 99 LINCOLN ELECTRIC Classic® 300 MP Service Manual only. Repeat this procedure until the entire face of the brush is contoured to the radius of the slip ring. 6. Check the brushes to be certain that there is spring tension holding them firmly against the slip rings.
  • Page 100 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.59 – Brush holder assembly location...

  • Page 101: Exciter Rotor Removal And Replacement Procedure

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 102 LINCOLN ELECTRIC Classic® 300 MP Service Manual 5. Check the rotor air gap, .017” minimum is allowed. 6. Using a 7/16” nutdriver and a 7/16” open-end wrench, attach the two bolts, nuts, lock washers and flat washers securing the brush holder bracket to the exciter stator frame.

  • Page 103: Exciter Stator Removal And Replacement Procedure

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 104 LINCOLN ELECTRIC Classic® 300 MP Service Manual 9. Using a slotted screwdriver, remove the screw securing the negative lead to contactor CR2. See Figure F.62. See Wiring Diagram. Label and disconnect the negative lead. 10. Label and disconnect leads 630 and 631 from the top terminals of contactor CR2. See Figure F.62.
  • Page 105 LINCOLN ELECTRIC Classic® 300 MP Service Manual Label and disconnect lead 820 from the ground stud on the lower control panel. See Figure F.68. See Wiring Diagram. Figure F.68. Label and Disconnect lead 11B from circuit breaker CB1 on the lower control panel.
  • Page 106 LINCOLN ELECTRIC Classic® 300 MP Service Manual 14. Connect lead 602C to the exciter field diode on the lower control panel. See Wiring Diagram. 15. Connect lead 203A to the 15 amp fuse holder on the lower control panel. See Wiring Diagram.
  • Page 107 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.61 – Cover and exciter wraparound cover locations Figure F.62 – CV box lead locations...
  • Page 108 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.63 – CV box component mounting hardware locations Figure F.64 – Finger guard panel location...
  • Page 109 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.65 – Control board plug locations Figure F.66 – Selector switch lead locations...
  • Page 110 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.67 – Positive output terminal and finger guard panel location Figure F.68 – Lower control panel plug and lead locations...
  • Page 111 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.69 – Front panel mounting screw locations Figure F.70 – Exciter stator mounting hardware locations...

  • Page 112: Generator Frame Removal And Replacement Procedure

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 113 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.71 – Generator frame mounting hardware locations...

  • Page 114: Generator Armature Removal And Replacement Procedure

    If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
  • Page 115 LINCOLN ELECTRIC Classic® 300 MP Service Manual Figure F.72 – Generator armature mounting bolt and rope sling attachment locations Figure F.73 – Generator armature mounting bolt and rope sling attachment locations...

  • Page 116: Retest After Repair

    LINCOLN ELECTRIC Classic® 300 MP Service Manual RETEST AFTER REPAIR Retest a machine: • If it is rejected under test for any reason that requires you to remove any part which could affect the machine’s electrical characteristics. • If you repair or replace any electrical components.

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