Lincoln Electric LN-25 SVM114-C - Manual (Page 33)

TABLE OF CONTENTS
- THEORY OF OPERATION SECTION -
LN-25™
Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section E
General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E-2
Control Circuit Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E-2
Input Power Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E-2
Welding Current Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E-2
Feedback and Control Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E-3
Trigger Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E-3
Optional Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E-4
Contactor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E-4
Gas Solenoid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E-4
Protective Devices & Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E-5
Overvoltage Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E-5
Motor Overload Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E-5
Control PC Board Fuses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E-5
Section E Section E
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FIGURE E.1 THEORY OF OPERATION BLOCK DIAGRAM
ELECTRODE
INPUT CABLE
TO WORK
SENSING LEAD
P
O
L
A
R
I
T
Y
S
W
I
T
C
H
VOLT
METER
CONTROL
BOARD
WIRE FEED
MODE SWITCH
SOLENOID
PC BOARD
GAS
SOLENOID
WIRE SPEED
CONTROL
RANGE
SWITCH
CONDUCTOR
BLOCK
M
O
T
O
R
HALL
EFFECT
MODULE
GUN
TRIGGER
CONNECTOR
OPTIONAL
CONTACTOR
BOARD
COLD
INCH
SWITCH
OPTIONAL
CONTACTOR
GUN CABLE
RPM FEEDBACK
ARMATURE VOLTAGE
EARLY MODELS ONLY - LATER MODELS HAVE CIRCUITRY
INCLUDED ON CONTROL BOARD