E-3
THEORY OF OPERATION
E-3
IDEALARC SP-250
CONSTANT VOLTAGE OUTPUT
The controlled DC output from the SCR rectifier
assembly is filtered by the capacitor bank and the out-
put choke, which is in series with the gun and welding
load, resulting in a constant voltage output at the out-
put terminals of the machine.
Figure E.4 - Constant Voltage Output
POWER SUPPLY OPERATION (CONTINUED)
LINE
SWITCH
MAIN
TRANSFORMER
RECONNECT
FAN
MOTORS
SCR
RECTIFIER
C
A
P
A
C
I
T
O
R
S
SHUNT
CHOKE
WIRE
DRIVE
MOTOR
TACH
POSITIVE
TERMINAL
NEGATIVE
TERMINAL
GAS
SOLENOID
PIEZO
ALARM
KEYPAD
CONTROL BOARD
FEEDBACK
GUN TRIGGER AND THUMB SWITCH
F
E
E
D
B
A
C
K
G
A
T
E
I
G
N
S
A
L
LCD
DISPLAY
NOTE: Unshaded areas of Block Logic
Diagram are the subject of discussion
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