Lincoln Electric SVM144-B service manual Theory of Operation, Input Line Voltage, Main Transformer

Page 32

E-2

THEORY OF OPERATION

E-2

TOC

TOC

FIGURE E.2 — INPUT LINE VOLTAGE AND MAIN TRANSFORMER.

 

 

 

 

 

 

 

Section

Master

 

GAS

FAN

 

 

 

 

 

SOLENOID

MOTOR

 

WIRE

 

 

 

 

 

 

 

 

 

 

DRIVE

 

 

 

 

 

MOTOR

 

to

to

WIRE

 

 

 

 

 

 

SPEED

 

 

 

 

 

 

Return

Return

 

 

 

 

 

 

ARC

CONTROL

 

 

 

 

VOLTAGE

BOARD

 

 

 

 

 

 

 

 

TACH

 

 

 

 

 

 

 

 

 

 

115 VAC

 

 

 

 

GUN TRIGGER

 

 

 

 

RECTIFIER

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

DIODE

G

 

 

FEEDBACK

 

 

 

 

BRIDGE

 

 

 

 

 

 

A

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

30 VAC

 

T

 

 

 

 

 

 

 

 

E

 

 

 

 

 

 

LINE

SNUBBER

S

 

 

 

 

 

 

BOARD

 

 

 

 

 

 

SWITCH

 

I

 

 

 

 

 

 

 

 

G

 

 

 

 

 

 

 

 

N

 

 

 

 

TOC

TOC

 

 

A

 

 

 

 

 

 

L

 

 

 

 

 

 

 

 

 

 

 

Section

Master

 

 

POWER

C

F

OUTPUT

POSITIVE

RECONNECT

 

ENHANCEMENT

A

CHOKE

 

TERMINAL

MAIN

 

CHOKE

P

E

 

 

 

 

TRANSFORMER

SCR

 

A

E

 

 

to

to

 

 

C

D

 

 

 

RECTIFIER

 

I

B

 

 

Return

Return

 

 

 

T

A

 

 

 

 

 

O

C

 

NEGATIVE

 

 

 

R

K

 

 

 

 

 

TERMINAL

 

 

 

S

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SHUNT

 

 

 

INPUT LINE VOLTAGE

gate drive circuitry. The weld power windings connect

 

 

AND MAIN TRANSFORMER

to the main SCR Rectifier and via the Snubber Board

 

 

to the Rectifier Diode Bridge. This AC voltage is recti-

 

 

 

 

 

The desired single phase input power is connected to

fied and then regulated by the control board. The

 

 

resultant +15 VDC and +5 VDC voltages supply power

TOC

TOC

the POWER MIG 255 through a line switch located on

to the control board circuitry. The 115 VAC winding (X8

the front panel.

and X9) supplies power, through the control board, to

 

 

Section

Master

A reconnect panel allows the user to configure the

the thermostatically controlled fan motor.

 

 

 

 

 

 

machine for the desired input voltage. This AC input

The fan is designed to come on automatically when

to

to

voltage is applied to the primary of the main trans-

weld arc is established. The fan will stay on for a mini-

former. The main transformer converts the high

mum of six minutes after the weld arc is terminated.

Return

Return

voltage, low current input power to a low voltage, high

The fan will also stay on when the machine’s welding

 

 

current output. In addition, the main transformer also

and feeding are disabled during thermostatic over-tem-

 

 

has an isolated center tapped 30 VAC auxiliary winding

perature protection. (See Thermal and Overload

 

 

that supplies power to the Control Board for the SCR

Protection.)

Section TOC

Master TOC

 

to

to

NOTE: Unshaded areas of Block Logic

Diagram are the subject of discussion

Return

Return

 

POWER MIG 255

 

 

Image 32
Contents Power MIG Safety Electric Shock can kill Safety Welding Sparks can cause fire or explosionPrécautions DE Sûreté Sûreté Pour Soudage a L’ArcMaster Table of Contents for ALL Sections Table of Contents Installation SectionInstallation Technical Specifications Power MIGLocation Safety PrecautionsUncrating the Power MIG Power MIG Figure A.2 Triple Voltage Machine Input Connections GUN and Cable Installation Shielding GASOperation Section Section BOPERATIONB-2 Fumes and Gases can be dangerousOperation Product DescriptionWelding Capability LimitationsDescription of Controls Procedure for Changing Drive and Idle Roll Sets Wire Reel Loading READI-REELS, SPOOLS, or CoilsFeeding Wire Electrode Setting RUN-IN Speed on STAN- Dard Power MIG FeederIdle Roll Pressure Setting To Start the WelderAvoiding Wire Feeding Problems Making a WeldFAN Control Input Line Voltage ProtectionAccessories Section Section CAccessories Drive Roll KitsK363P READI-REEL Adapter Dual Cylinder Mounting KIT K1702-1Operating Instructions For Timer KIT Making a Weld with the Spool GUN, Spool GUN Installed Spool GUN Adapter KITMaintenance Section Section DGUN Tubes and Nozzles MaintenanceRoutine and Periodic Maintenance Figure D.1 Component Locations Contact TIP and GAS Nozzle Installation Liner Removal Replacement5MAINTENANCED-5 To open up the handleTable D.2 Description English Size Metric SizeTheory of Operation Section Section EMain Transformer Theory of OperationInput Line Voltage Output Rectification Feedback ControlConstant Voltage Output Figure E.4 Constant Voltage OutputWire Drive Motor FeedbackOvercurrent Protection Wire Feed Overload ProtectionThermal and Overload Protection SCR Operation Figure E.6 SCR OperationPower MIG Troubleshooting & Repair Section Section FTroubleshooting & Repair HOW to USE Troubleshooting GuidePC Board Troubleshooting Procedures WorkstationsOutput Problems SCR Rectifier Rectifier Function Problems Wire Feeding Problems Welding Problems Welding Problems Main Transformer Test Test DescriptionTest Procedure Main Transformer TestFigure F.1 Troubleshooting and Repair Materials Needed Rectifier Diode Bridge TestTest Description Rectifier Diode Bridge Testing 208R 206 28 VAC 209R Power MIG Static SCR Rectifier Assembly Test Static SCR Rectifier Assembly Test Active SCR Rectifier Assembly Test Power MIG Active SCR Rectifier Assembly Test Active SCR Rectifier Assembly Test Figure F.7 Location Leads X2 Open switch SW-1 Wire Drive Motor and Tachometer Feedback Test Wire Drive Motor and Tachometer Feedback Test Test for Supply Voltage to Tachometer 515B 206B 15 VDC 5J1 1J1Test for Feedback Voltage to Control Board 555 206B To 3.5 VDC 6J1 1J1Normal Open Circuit Voltage Waveform VoltsMachine Loaded to 250 Amps AT 26 VDC Scope Settings Typical Output Voltage Waveform Machine LoadedMachine Loaded to 220 Amps AT 22 VDC Scope Settings Troubleshooting & Repair Typical SCR Gate Voltage Waveform Power MIG Control PC Board Removal and Replacement Procedure DescriptionRemoval and Replacement Procedure Control PC BoardFigure F.11 Control Board Mounting Power MIG 41TROUBLESHOOTING & REPAIRF-41 Wire Drive Assembly Removal and Replacement ProcedureWire Drive Assembly Removal and Replacement ProcedureTOC Power MIG SCR Output Rectifier Removal and Replacement Procedure SCR Output Rectifier Removal and Replacement Figure F.15 Right Heat Sink Lead Disconnection Power MIG Capacitor Bank Removal and Replacement Procedure Capacitor Bank Removal and Replacement Troubleshooting & Repair Removal and Replacement Main Transformer and Output ChokeTOC Power MIG FAN Motor Assembly Removal and Replacement Procedure FAN Motor Assembly Removal and Replacement Troubleshooting and Repair Wire Speed RangeRetest After Repair Open Circuit VoltagePower MIG Electrical Diagrams Section Power MIG 255 208/230V Wiring Diagram Entire Machine Code 10563 L10979Power MIG 255 230/460/575V Wiring Diagram Entire Machine Code 10583 L10980Power MIG 255 230/460/575 Wiring Diagram Entire Machine Code 10986 L11980Power MIG 255 208/230 Wiring Diagram Entire Machine Code 10990 L11979Control PC Board Schematic G3520-1D1 Control PC Board Assembly G3521-1 3521Display PC Board Schematic L10951 PowermigDisplay PC Board Assembly L10952-1 Lincoln Electric COSnubber PC Board Schematic S24374 24374 SSnubber PC Board Assembly M19248-1 00 ~.04SVM Error Reporting Form