Lincoln Electric MULTI-SOURCE SVM155-A - Manual (Page 23)

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Section E-1 Section E-1
MULTI-SOURCE
FIGURE E.1 – MULTI-SOURCE BLOCK LOGIC DIAGRAM
LED LED LED
DIGITAL
METER
G Y W
CONTROL
BOARD
THERMOSTAT
CONTROL
SIGNAL
RESISTOR
BANK FIRING
BOARD
GATE SIGNALS
TO CONTROL
BOARD
SHUNT
SCR OUTPUT RECTIFIER
FILTER
CAPACITOR
LIMITING
RESISTOR
WORK
TERMINAL
ELECTRODE
TERMINAL
T1
MAIN
TRANSFORMER
INPUT
CONTACTOR
CONTROL
TRANSFORMER
THERMOSTAT SWITCH
CONTROL
BOX
RECTIFIER
FAN
R
E
C
O
N
N
E
C
T
SURGE
NOISE
FILTER
T2
F
AN VOL
T
AGE
120 V
AC
CONT
ACT
OR
32 V
AC
32 V
AC
32 V
AC
TO CONTROL
BOARD
Theory of Operation Section ............................................................................................... Section E
General Description ..............................................................................................................E-2
Input Voltage, Filter, Contactor and Control Transformer ....................................................E-2
Main Transformer, Control Board, Cooling Fan Motor, Digital Meter & LED’s .....................E-3
SCR Bridge, Resistor Bank, Firing Board, & Output Capacitor/Resistor ............................E-4
Protection Devices & Circuits...............................................................................................E-5
SCR Operation .....................................................................................................................E-6
TABLE OF CONTENTS
-THEORY OF OPERATION-