Miller S-74 MPa Plus Technical Manual
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Miller S-74 MPa Plus Technical Manual

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S-74 MPa Plus
CE
TM-273245D
2021−11
Eff. w/Serial No. MG135049U
Processes
MIG (GMAW) Welding
MIG (GMAW-P) Welding
Flux Cored (FCAW) Welding
(Gas- And Self-Shielded)
Description
Wire Feeder
Aluminum Push/Pull Capable
File: MIG (GMAW)

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  • Page 1 Eff. w/Serial No. MG135049U Processes MIG (GMAW) Welding MIG (GMAW-P) Welding Flux Cored (FCAW) Welding (Gas- And Self-Shielded) Description Wire Feeder Aluminum Push/Pull Capable S-74 MPa Plus For product information, Owner’s Manual translations, and more, visit File: MIG (GMAW) www.MillerWelds.com...

  • Page 2: Table Of Contents

    TABLE OF CONTENTS SECTION 1 − SAFETY PRECAUTIONS FOR SERVICING ........1-1.
  • Page 3 ..............9-2. Troubleshooting Circuit Diagram For S-74 MPa Plus .

  • Page 5: Section 1 − Safety Precautions For Servicing

    D To handle hot parts, use proper tools and/or wear heavy, insu- Turn off unit, disconnect input power, and discharge input capaci- lated welding gloves and clothing to prevent burns. tors according to instructions in Manual before touching any parts. S-74 MPa Plus TM-273245 Page 1...

  • Page 6: California Proposition 65 Warnings

    2. Do not place your body between welding cables. Arrange cables If cleared by your doctor, then following the above procedures is recom- to one side and away from the operator. mended. TM-273245 Page 2 S-74 MPa Plus...

  • Page 7: Section 2 − Definitions

    SECTION 2 − DEFINITIONS 2-1. Additional Safety Symbols And Definitions Some symbols are found only on CE products. Warning! Watch Out! There are possible hazards as shown by the symbols. Safe1 2012−05 Do not discard product (where applicable) with general waste. Reuse or recycle Waste Electrical and Electronic Equipment (WEEE) by disposing at a designated collection facility.
  • Page 8 Wear hat and safety glasses. Use ear protection and button shirt collar. Use welding helmet with correct shade of filter. Wear complete body protection. Safe66 2012−06 Become trained and read the instructions before working on the machine or welding. Safe65 2012−06 Notes TM-273245 Page 4 S-74 MPa Plus...

  • Page 9: Miscellaneous Symbols And Definitions

    2-2. Miscellaneous Symbols And Definitions Some symbols are found only on CE products. Rated Welding Amperes Output Current Direct Current (DC) Program Duty Cycle Degree Of Protection Preflow Time Primary Current Hertz Line Connection Wire Type Set Up Conventional Arc Length Increase Load Voltage Process...

  • Page 10: Section 3 − Specifications

    There can be potential difficulties in ensuring electromagnetic compatibility in those locations, due to con- ducted as well as radiated disturbances. ce-emc 3 2014-07 C. Temperature Specifications Operating Temperature Range Storage/Transportation Temperature Range −4 to 131°F (−20 to 55°C) 14 to 104°F (−10 to 40°C) Temp1_016- 08 TM-273245 Page 6 S-74 MPa Plus...
  • Page 11 Indicates that the concentration of the Hazardous Substance in at least one homogeneous material of the part is above the relevant threshold of China GB/T 26572.   ‡ SJ/Z11388 The EFUP value of this EEP is defined in accordance with China SJ/Z 11388. EEP_2016−06 Notes S-74 MPa Plus TM-273245 Page 7...

  • Page 12: Section 4 − Installation

    Regulator (Customer Supplied) Shielding gas pressure not to exceed 100 psi (689 kPa). Welding Power Source Running Gear Water Cooling System Do not move or operate unit where it could tip. loc_feeder/running gear 2015-05 TM-273245 Page 8 S-74 MPa Plus...

  • Page 13: Equipment Connection Diagrams

    Contactor Control/Power Cord Positive (+) Weld Cable Negative (−) Weld Cable Workpiece Welding Gun Wire Feeder Gas Hose Gas Cylinder and Regulator (Customer Supplied) Shielding gas pressure not to exceed 100 psi (689 kPa). 246040-C S-74 MPa Plus TM-273245 Page 9...

  • Page 14: Rear Panel Connections And Rotating Drive Assembly

    Drive Assembly Drive Assembly Rotation Knob To rotate the drive assembly, loos- en drive assembly rotation knob, rotate drive assembly, and tighten knob. Gas Hose (Customer Supplied) Tools Needed: 9/16, 5/8 in. 3/16 in. 246041-D TM-273245 Page 10 S-74 MPa Plus...

  • Page 15: 14-Pin Plug Information For Connecting Wire Feeder To Power Source

    Rated Speed Range (per IEC 60974−5) Standard .035 To .062 in. (0.9 To 1.57 mm) 55 To 770 ipm (1.4 To 19.6 mpm) Standard 5/64 in. (2 mm) 55 To 700 ipm (1.4 To 17.8 mpm) Notes S-74 MPa Plus TM-273245 Page 11...

  • Page 16: Installing Welding Gun

    Installing A Push Only Gun When using a push only gun, re- move the blocking clips and place them in the empty pressure slots for storage and adjust pressure as shown in Section 4-7. 245985-B / Ref. 246040-C TM-273245 Page 12 S-74 MPa Plus...

  • Page 17: Installing And Threading Welding Wire

    Push wire through guides up to drive rolls; continue to hold wire. Press Jog button to feed wire out gun. Ref. 156 929-A / Ref. 150 922 / Ref. 156 930 / S-0627-A S-74 MPa Plus TM-273245 Page 13...

  • Page 18: Section 5 − Operation

    • Jog speed can be adjusted by the Adjust regulator. TM-273245 Page 14 S-74 MPa Plus...

  • Page 19: Front Panel Controls

    (See Section 5-6) Right Display (See Section 5-5) Start Push Button (See Section 5-8) Program Select Push Button Adjust Control Left (See Section 5-6) (See Section 5-10) Crater Push Button (See Section 5-9) Notes S-74 MPa Plus TM-273245 Page 15...

  • Page 20: Left Display

    Amps LED the amperage is above a minimum value of words, if the Adjust control is activated while The LEDs below the display illuminate to indi- welding, the unit displays and permits ad- 25 Amps. TM-273245 Page 16 S-74 MPa Plus...

  • Page 21: Adjust Control Left/Right

    5-10. Program Select Push Button Program Select Push Button Program Indicating LEDs Program select is for setup ad- justments and initial weld. Active function (TPS or Dual Schedule) will override previous functions. S-74 MPa Plus TM-273245 Page 17...

  • Page 22: Power Source Selection Menu

    Vmin =10 Vmax =38 Custom Vmin =10 Vmax =38 CUST PWR.S ** For any power sources not listed, pick a matching voltage range or see Section 5-6 to set Vmin and Vmax. Ref. 271 487-A TM-273245 Page 18 S-74 MPa Plus...

  • Page 23: Operational Terms

    Start Provides voltage/arc length, wire feed speed and time values for modified arc start. Profile Pulse Profile Pulse optimizes aluminum weld bead appearance by producing welds with consistently spaced ripple patterns, similar to GTAW. S-74 MPa Plus TM-273245 Page 19...

  • Page 24: Section 6 − Setting Sequence Parameters

    6. Postflow 0.0-10.0 7. Retract 0.0-1.5 X = Setting available. Weld Time Crater Retract Time If Selected Preflow Start Postflow Time Time Time Time Run-In Start Weld Crater Postflow Sequence Preflow Trigger Trigger Pressed Released TM-273245 Page 20 S-74 MPa Plus...

  • Page 25: Section 7 − Programming

    Crater time source with a single tap of the welding MENU when PROFILE PULSE is act- must be set for at least 0.2 seconds to gun trigger. ive. See Section 7-7. Notes S-74 MPa Plus TM-273245 Page 21...

  • Page 26: Setup Menu Level 2

    MIG process, and varies with the selected Profile Pulse Menu (PROF) − Allows Pro- sion level will momentarily appear following wire and gas program in the PULSED MIG file Pulse to appear in the Setup Menu. a short delay. TM-273245 Page 22 S-74 MPa Plus...

  • Page 27: Setting A Start Sequence In Synergic Pulse

    Range the weld wire feed speed setting. Range of in the RIGHT DISPLAY. of this setting is from (X0.50 to X1.50). this setting is from (0.1 to 5.0) seconds. S-74 MPa Plus TM-273245 Page 23...

  • Page 28: Setting A Start Sequence In Non−Synergic Pulse Or Mig

    (0.0 to 100.0) and the level is the weld wire feed speed setting. Range of DISPLAY. Rotate the RIGHT ADJUST set to match start WFS. this setting is from (0.1 to 5.0) seconds. TM-273245 Page 24 S-74 MPa Plus...

  • Page 29: Setting A Crater Fill Sequence In Synergic Pulse

    50 and ARC.L is X0.50, the Crater Arc less than the set time. Range of this setting To exit the CRATER MENU press and re- Length is 25. is from (0.1 to 5.0) seconds. S-74 MPa Plus TM-273245 Page 25...

  • Page 30: Setting A Crater Fill Sequence In Non−Synergic Pulse Or Mig

    Crater Voltage (VOLT) − Sets the voltage less than the set time. Range of this setting in the RIGHT DISPLAY. during the Crater Fill time. Range of this set- is from (0.1 to 5.0) seconds. TM-273245 Page 26 S-74 MPa Plus...

  • Page 31: Profile Pulse

    Press and release Setup button one last time, and the front display will illuminate as if it were turned on. SET UP will be exited back to the normal voltage and wire feed speed display. Reset is now complete. S-74 MPa Plus TM-273245 Page 27...

  • Page 32: Section 8 − Theory Of Operation

    The analog signals, of wire speed and arc voltage, are converted to a digital signal by motor board PC1. Motor board PC1 communicates with di- gital meter board PC2 using serial communication. AC Or DC Control Circuits TM-273245 Page 28 S-74 MPa Plus...

  • Page 33: Section 9 − Troubleshooting

    See Section 9-2 for test points and values, and Section NO TAG and following for parts location. Use Miller Testing Booklet (Part No. 150 853) when servicing this unit. See the Miller Extranet for service memos that may aid in the repair of this product. Trouble Remedy Unit completely inoperative.
  • Page 34 Check 14-pin filter board and connections, and replace if necessary (see Section 9-10). Shielding gas does not flow when Purge Clean filter screen in valve. switch is pressed. Check continuity of Purge switch S2, and replace if necessary. Clear blockage in welding gun. TM-273245 Page 30 S-74 MPa Plus...
  • Page 35 Check motor board PC1 and connections, and replace if necessary (see Section 9-4). Check 14-pin filter board and connections, and replace if necessary (see Section 9-10). S-74 MPa Plus TM-273245 Page 31...

  • Page 36: Troubleshooting Circuit Diagram For S-74 Mpa Plus

    9-2. Troubleshooting Circuit Diagram For S-74 MPa Plus See Section 9-4 for PC1 information See Section 9-11 for PC8 information V7 V8 +10 VDC See Section 9-9 for PC5 information TM-273245 Page 32 S-74 MPa Plus...
  • Page 37 +3.5 VDC in MIG mode, +2.5 VDC in Pulse +1.5 VDC or +7.2 VDC at rest, +3.4−4 VDC See Section 9-7 when running for PC2 information +0.35 VDC or +3 VDC at rest, +1.6 VDC when running Test Equipment Needed: 244221-G S-74 MPa Plus TM-273245 Page 33...

  • Page 38: Location Of Circuit Boards

    Location Of Circuit Boards Motor Board PC1 (See Section 9-4) User Interface Board PC2 (See Section 9-7) 14 Pin Filter Board PC5 (See Section 9-9) Trigger Filter Board PC8 (See Section 9-11) 246 913-C TM-273245 Page 34 S-74 MPa Plus...
  • Page 39 18 Gauge (.050 in.) 16 Gauge (.063 in.) 14 Gauge (.078 in.) 1/8 in. (.125 in.) 3/16 in. (.188 in.) 1/4 in. (.25 in.) 5/16 in. (.313 in.) 3/8 in. (.375 in.) 1/2 in. (.5 in.) S-74 MPa Plus TM-273245 Page 35...

  • Page 40: Motor Board Pc1 Testing Information

    Be sure plugs are secure before testing. See Section 9-5 for specific values during testing. Motor Board PC1 RC11 RC12 No testing required for remain- ing plugs and receptacles. Test Equipment Needed: 246913-C / 272238-A TM-273245 Page 36 S-74 MPa Plus...

  • Page 41: Motor Board Pc1 Test Point Values

    Command voltage/arc length 0−10 volts DC reference to RC4−11 Wire feed speed command 0−10 volts DC reference to RC4−12 Process Select CC/CV select 3.5 volts DC in MIG, 2.5 volts DC in pulse referenced to RC4−12 Contactor 24 volts AC reference RC5−2 S-74 MPa Plus TM-273245 Page 37...
  • Page 42 Tach signal 60 pulses per 1 RPM of motor 183Hz to 2.5kHz or 4 to 3.4 volts DC when running Tach common Tach power +15 volts DC RC100 Chassis ground No testing required for remaining plugs and receptacles. TM-273245 Page 38 S-74 MPa Plus...

  • Page 43: Diagnostic Led's On User Interface Board Pc2

    If LED1 and LED2 are on − power supply circuits on motor board are working properly. If LED1 and LED2 are off − Check power coming into motor board, and/or replace motor board. If LED1 or LED2 is off − Replace motor board. S-74 MPa Plus TM-273245 Page 39...

  • Page 44: User Interface Board Pc2 Testing Information

    User Interface Board PC2 Test Point Values PC2 Voltage Readings ± a) Tolerance − 10% unless specified Receptacle Value RC9−1 5 volts DC DGND DGND 5 volts DC B serial comm A serial comm TM-273245 Page 40 S-74 MPa Plus...
  • Page 45 18 Gauge (.050 in.) 16 Gauge (.063 in.) 14 Gauge (.078 in.) 1/8 in. (.125 in.) 3/16 in. (.188 in.) 1/4 in. (.25 in.) 5/16 in. (.313 in.) 3/8 in. (.375 in.) 1/2 in. (.5 in.) S-74 MPa Plus TM-273245 Page 41...

  • Page 46: Pin Filter Board Pc5 Testing Information

    14 Pin Filter Board PC5 Testing Information Be sure plugs are secure before testing. See Section 9-10 for specif- ic values during testing. 14 Pin Filter Board PC5 RC30 RC32 RC31 Test Equipment Needed: 246913-C / 244201-D TM-273245 Page 42 S-74 MPa Plus...

  • Page 47: Pin Filter Board Pc5 Test Point Values

    Wire feed speed command 0−10 volts DC reference to RC30−5 Process Select Mig 3.5 volts Pulse 2.5 volts Contactor 24 VAC reference RC31−2 Not used Reed & Flow common Reed Flow Common Wire feed speed common S-74 MPa Plus TM-273245 Page 43...

  • Page 48: Trigger Filter Board Pc6 Testing Information

    Be sure plugs are secure before testing. See Section 9-12 for specif- ic values during testing. Trigger Filter Board PC6 No testing required for remain- ing plugs and receptacles. Test Equipment Needed: RC19 RC13 RC18 246913-C / 244208-G TM-273245 Page 44 S-74 MPa Plus...

  • Page 49: Trigger Filter Board Pc6 Test Point Values

    Purge 0 volts DC/15 volts DC when purged Gun command common RS485A RS485B ISO SW OUT +15 volts DC RC19 Jog 0 volts DC/15 volts DC when jogged Purge 0 volts DC/15 volts DC when purged SW OUT +15 volts DC S-74 MPa Plus TM-273245 Page 45...
  • Page 50 Gun command pot 0 − 5 volts DC reference to RC21−8 Gun sense 2.7V for AlumaPro Plus reference to RC21−14 RS485A RS485B Gun command common RC100 Chassis ground No testing required for remaining plugs and receptacles. TM-273245 Page 46 S-74 MPa Plus...

  • Page 51: Tachometer Board Pc51 Testing Information

    Of Cover 0.5 ms 2 V Test Equipment Needed: Tools Needed: Pulse Output At 200 IPM; Scope On Pin 1 And Pin 2 (Circuit Common); Frequency (Not Voltage) Changes 237049−B / 153632-D / Ref. 137394 S-74 MPa Plus TM-273245 Page 47...

  • Page 52: Section 10 − Maintenance

    Indicates a front panel pcb error. If this error occurs, replace Interface/Display board PC2. R.Tac Indicates the right push motor tachometer circuit has an error. L.Tac Indicates the left push motor tachometer circuit has an error. G.Tac Indicates tachometer in push-pull gun has an error. TM-273245 Page 48 S-74 MPa Plus...

  • Page 53: Section 11 − Electrical Diagrams

    The following is a list of all diagrams for models covered by this manual. Model Serial Or Style Number Circuit Diagram Wiring Diagram S-74 MPa Plus MG135049U and following 244221-G ♦ Circuit Board PC1 MG135049U and following 272239-C♦...
  • Page 54 Figure 11-1. Circuit Diagram For S-74 MPa Plus Eff. w/Serial No. MG135049U And Following TM-273245 Page 50 S-74 MPa Plus...
  • Page 55 Left Gun Trigger Connector Right Gun Trigger Connector 244221-G S-74 MPa Plus TM-273245 Page 51...
  • Page 56 USA & Canada FAX: 920-735-4134 International FAX: 920-735-4125 For International Locations Visit www.MillerWelds.com Proprietary Information - Do not distribute or allow to be used by unqualified persons. © ORIGINAL INSTRUCTIONS − PRINTED IN USA 2020 Miller Electric Mfg. LLC 2020−01...

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