Lincoln Electric IDEALARC SP-255 Service Manual page 49

E-3
POWER SUPPLY OPERATION (CONTINUED)
MAIN
LINE
TRANSFORMER
SWITCH
RECONNECT
FAN
MOTORS
CONSTANT VOLTAGE OUTPUT
The controlled DC output from the SCR rectifier assem-
bly is filtered by the capacitor bank and the output
choke, which is in series with the gun and welding load,
resulting in a constant voltage output at the output ter-
minals of the machine.
THEORY OF OPERATION
PIEZO GAS
ALARM SOLENOID
LCD
DISPLAY
KEYPAD
CONTROL BOARD
G
A
T
E
S
I
G
N
A
L
SCR
RECTIFIER
Figure E.4 - Constant Voltage Output
NOTE: Unshaded areas of Block Logic
Diagram are the subject of discussion
IDEALARC
WIRE
DRIVE
MOTOR
TACH
GUN TRIGGER AND THUMB SWITCH
FEEDBACK
POSITIVE
TERMINAL
CHOKE
C
A
F
P E
A E
C D
I B
T A
O C
R K
NEGATIVE
S
TERMINAL
SHUNT
® SP-255
E-3