Lincoln Electric POWER MIG SVM167-A Service Manual page 33

E-3
FAN
MOTOR
LINE
SWITCH
RECONNECT
PANEL
TRANSFORMER
OUTPUT RECTIFICATION,
CONTACTOR AND CONTROL
BOARD
The AC voltage developed on the secondary
winding is applied, through the selector switch
and output contactor, to the output rectifier
bridge. This DC welding voltage is filtered by
the output capacitors and applied to the output
terminals and welding gun. Since the output
choke is in series with the positive leg of the
output rectifier and also in series with the gun
and welding load, a filtered constant voltage
output is applied to the output terminals of the
machine.
NOTE: Unshaded areas of block logic diagrams are the subject of discussion.
THEORY OF OPERATION
FIGURE E.3 – CONTROL CIRCUITS.
GAS
SOLENOID
CONTROL BOARD
RECTIFIER
DIODE
BRIDGE
TAP SELECTOR
SWITCH
CONTACTOR
MAIN
POWER MIG® 215
WIRE
SPEED
CONTROL
WIRE
DRIVE
MOTOR
TRANSFORMER
TACH
THERMOSTAT
GUN TRIGGER
OUTPUT DIODE
BRIDGE
+
+
OUTPUT
POSITIVE
CHOKE
TERMINAL
OUTPUT
CAPACITORS
- -
NEGATIVE
TERMINAL
OUTPUT BRIDGE
THERMOSTAT
GUN
ASSEMBLY
E-3