Lincoln Electric SVM141-A service manual Theory of Operation, Input Power Circuit

Page 34

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E-2

E-2

THEORY OF OPERATION

FIGURE E.2 – MAIN TRANSFORMER AND INPUT POWER

 

 

BY-PASS

 

 

BOARD

 

POLARITY

WORK

 

 

 

SWITCH

ELECTRODE

 

 

MAIN

 

HI-FREQUENCY

TRANSFORMER

 

TRANSFORMER

RECONNECT

INPUT

 

 

 

 

 

 

 

POWER

 

 

 

 

 

 

 

PANEL

SWITCH

 

 

 

 

 

 

C

 

 

 

 

 

 

 

 

 

 

H1

 

 

 

 

 

H

 

 

X1

AC

DC+

 

 

O

 

 

 

 

 

 

 

 

 

 

K

 

 

 

 

SCR

 

 

 

 

 

 

 

 

E

 

 

 

 

BRIDGE

 

 

 

 

H2

X2

 

 

SHUNT

HIGH VOLTAGE

 

 

 

AC

DC-

TRANSFORMER

 

 

H3

 

 

 

 

 

 

 

 

 

F

CIRCUIT

 

 

 

 

 

 

 

 

 

 

H4

 

 

 

 

E

 

 

 

23VAC

 

 

 

E

 

 

 

 

 

 

 

D

 

 

 

 

 

 

 

 

B

 

 

 

 

 

 

 

 

A

 

"A"

 

 

 

 

 

 

C

 

 

 

 

 

 

 

K

 

 

 

 

18VAC

 

 

 

 

115VAC

 

 

 

18VAC

 

 

CONTROL

MODE

115VAC

 

 

 

SWITCH

 

115VAC

 

 

BOARD

 

RECEPTACLE

 

 

 

 

 

 

 

 

THERMAL

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

LIGHT

 

 

FAN

 

 

 

 

 

THERMOSTATS

 

 

 

 

 

 

 

 

 

 

REMOTE

 

 

 

 

 

 

 

 

RECEPTACLE

DOWNSLOPE GAS

POSTFLOW

BALANCE

OUTPUT

 

 

 

 

 

 

CONTROL

VALVE

CONTROL

CONTROL

CONTROL

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GENERAL DESCRIPTION

The Square Wave TIG 275 machine is a constant cur- rent, single range square wave AC/DC TIG (GTAW) arc welding power source with built-in high frequency sta- bilization. It also has stick welding (SMAW) capability. The machine includes advanced features such as Digital Voltage and Current Meters, Auto Balance, 2- Step/4-Step operation, adjustable Downslope Time Control and Fan as Needed. The Square Wave TIG 275 is recommended for the TIG (GTAW) and stick (SMAW) welding processes within its output capacity of 5 to 315 amps, on both AC and DC polarities.

INPUT POWER CIRCUIT

The desired single-phase input power is connected to the TIG 275 through the reconnect panel to the input power switch located in the front panel of the machine. The machine can be configured for any one of three input voltages (208 VAC, 230 VAC or 460 VAC) by con- necting the “A” lead to the appropriate terminal on

the reconnect panel. When the input power switch is turned “on,” the input voltage is applied directly to the primary winding of the main transformer.

The main transformer changes the high voltage, low current input power to a low voltage, high current out- put available at the main secondary winding (X1 and X2). This 78 VAC winding supplies power to the weld- ing arc. In addition, four auxiliary windings are incor- porated in the main transformer. The 115 VAC winding supplies power to the 115 VAC receptacle. Through the control board, it also powers the gas solenoid, the high voltage transformer, and the cooling fan. The cooling fan is activated only when welding current is sensed. The 23 VAC winding provides power for the DC background current. This circuit is active in the DC welding mode. Two 18 VAC windings are included in the main transformer assembly. One 18 VAC winding is rectified on the control board and is used in the trig- ger circuitry. The other 18 VAC winding is used by the control board for phase detection. This voltage is also rectified and regulated to +15 VDC and +5 VDC power supplies that operate the circuitry on the control board.

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NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.

SQUARE WAVE TIG 275

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Contents Safety Depends on You Square Wave TIGSafety Square Wave TIGARC Rays can burn Electric Shock can killFumes and Gases can be dangerous Cylinder may explode if damaged IiiPrécautions DE Sûreté Sûreté Pour Soudage a L’ArcMaster Table of Contents for ALL Sections Table of Contents Installation Section Installation Technical Specifications Square Wave TIGSafety Precautions Input Supply Connections Figure A.1Input Reconnect Procedure Return to Section TOC To Section TOCWork Cable Connection User Supplied ConnectorsOutput Connections Table A.1TIG Torch Connection Cylinder could explode if damagedTWIST-MATE Adapter for LA-9 and LA-17 TIG Torch TWIST-MATE Adapter for LW-18 and LW-20 TIG TorchCompleted Assembly Square Wave TIG Table of Contents Operation Section Fumes and Gases can be dangerous OperationElectric Shock can kill Welding Sparks can cause fire or explosionGeneral Description Design Features AdvantagesRecommended Processes and Equipment Welding Capability LimitationsControls and Settings Figure B.1 Control PanelTIG Welding Guidelines Welding OperationTIG Welding Twist Mate ElectrodeTable B.2 Recommended Polarity Settings for TIG Welding TIG Welding Sequence of Operation 2-Step TIG ModeTIG Welding Sequence of Operation 4-Step TIG Mode Hand and Foot Amptrol Operation Advanced TIG Welding FeaturesAC Wave Balance and Auto Balance Hertz Domestic Machines Auxiliary PowerStick Welding 50/60 Hertz European MachinesSquare Wave TIG Table of Contents Accessories Section C-1Section C-1Optional Accessories Accessories Included with MachineK963-1, -2 Hand Amptrol Table of Contents Maintenance Section Routine and Periodic Maintenance MaintenanceOverload Protection Control PC Board Component Location and AccessSpark GAP ASSEMBLY, High Voltage Transformer Display PC BOARD, ARC STARTER/BYPASS PC BoardFigure D.2 Major Component Locations Table of Contents Theory of Operation Section Input Power Circuit Theory of OperationOutput Rectification Control Board and Feedback Figure E.3 Output RECTIFICATION, Control Board and FeedbackHigh Voltage / High Frequency Circuit Figure E.4 High Voltage / High Frequency CircuitDC Welding Output Figure E.5 DC Welding OutputAC Welding Output Figure E.7 AC Welding OutputSCR Operation Figure E.9 SCR OperationThermal Protection Protective CircuitsOverload Protection Table of Contents Troubleshooting & Repair Section Disable Procedure Troubleshooting & RepairHOW to USE Troubleshooting Guide High Voltage / High Frequency can damage test equipmentPC Board Troubleshooting Procedures PC Board can be damaged by static electricityObserve Safety Guidelines Troubleshooting GuideDetailed in the beginning of this manual Perform the SCR Bridge Test Troubleshooting & Repair Connections Troubleshooting Guide Troubleshooting & Repair TIG Welding Problems Electric Shock Can KillTroubleshooting & Repair To Technical Specifications Stick Welding Problems Function Problems 15F-15Function Problems Installation Troubleshooting & Repair Test Description High Frequency Circuit Disable ProcedureMaterials Needed High Frequency Circuit Disable Procedure ProcedureT1 Main Transformer Test Test Procedure T1 Main Transformer TestReplace the case side covers Test Points Primary WINDINGS1GAS Water Solenoid Test GAS Water Solenoid Test Figure F.3 GAS Solenoid LocationStatic SCR Test Static SCR Test Figure F.4 Plug J1 Location on Control BoardAssembly Removal and Replacement Active SCR Test DescriptionActive SCR Test Figure F.6 Plug J1 Location on Control BoardFigure F.7 Active SCR Test Setup SCR Bridge Assembly Removal and Replacement Scope Settings AC TIG ModeNormal Open Circuit Voltage Waveform DC TIG Mode AC Stick Mode DC Stick Mode Machine Loaded to 255 Amps Typical Output Voltage Waveform Machine LoadedAT 30 VAC Machine Loaded to 275 Amps AT 31 VDCAC Stick Mode DC Stick Mode 50 V/Div High Voltage Transformer Removal Replacement Removal Procedure ReplacementHigh Voltage Transformer Removal Replacement Procedure Figure F.10 High Voltage Transformer Mounting InsulatorsSCR Bridge Assembly Removal and Replacement SCR Bridge Assembly Removal and Replacement Using the 3/8 nut driver, remove the caseFigure F.13 SCR Bridge Connections Refer to Figures F.11 F.13 Polarity Switch Removal and Replacement Polarity Switch Removal and Replacement Allen Screw Control Knobs Polarity Switch HandlePOS Micro Switch Leads Square Wave TIG 253Figure F.16 Polarity Switch Wiring Diagram Replacement Procedure For Steps 9--17, see Figure F.15 and F.16Description Main Transformer and Output Choke Assembly Removal and ReplacementFigure F.18 Transformer Connections Figure F.19 Polarity Switch Connections Choke NEG POS Micro Switch LeadsReassembly Procedure Refer to Figures F.17 F.19Input Idle Amps Minimum Acceptable Output Voltage AT Maximum Output SettingRetest After Repair Open Circuit VoltagesSquare Wave TIG Section G Electrical WiringDiagram L10747 TIGDiagram L10747-2 SquarewaveElectrical Diagrams Control Board Schematic G3358-1Control Board Schematic G3358-2 OCI4 TRI3 MT2Display Board Schematic L10768 Return to Section Return to Section TOC To Section TOCBypass Display Board Layout L10770-1 L10770-17-24-98XXX Bypass Board Layout L10121-1 10G-10Square Wave TIG

SVM141-A specifications

The Lincoln Electric SVM141-A is a cutting-edge solution designed for operators requiring precision, efficiency, and versatility in their welding applications. This machine is known for its compact form but robust feature set, making it an ideal choice for both professional welders and industrial applications.

One of the standout features of the SVM141-A is its advanced inverter technology. This innovation allows for a stable arc, providing consistent results even under varying conditions. The machine minimizes power consumption, making it energy-efficient without compromising performance. The inverter technology also supports a wider input voltage range, making the SVM141-A suitable for use in diverse environments and job sites.

Another key characteristic is its multi-process capability. The SVM141-A supports MIG, stick, and TIG welding processes, providing flexibility for various welding tasks. This versatility enables operators to tackle different materials, including mild steel, stainless steel, and aluminum, making it a valuable tool for numerous projects.

The user-friendly interface of the SVM141-A includes an intuitive digital display, which allows welders to adjust settings with ease. This feature is crucial for ensuring the right configurations for specific welding tasks, reducing the chances of errors and enhancing the overall finish of welds.

Safety is also a priority with the Lincoln Electric SVM141-A. It comes with built-in safety features such as overheat protection and automatic shutdown, ensuring operator safety and equipment longevity. The machine's lightweight design enhances portability, allowing it to be used in various workspaces with ease.

Durability is another hallmark of the SVM141-A. Constructed with high-quality materials, the machine is designed to withstand the rigors of demanding work environments. This ensures reliability over time, providing consistent performance even under heavy use.

In summary, the Lincoln Electric SVM141-A is a versatile, efficient, and user-friendly welding machine that appeals to a wide range of users. Its advanced inverter technology, multi-process capabilities, safety features, and durable construction make it a strong contender in the welding market, suitable for both professionals and hobbyists alike. Whether it’s for light fabrication, repairs, or industrial welding tasks, the SVM141-A meets diverse needs with precision and reliability.
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