Lincoln Electric IDEALARC CV-300 Service Manual page 35

E-2
POWER SUPPLY OPERATION (CONTINUED)
FAN
MOTOR
INPUT
RECONNECT
LINE
PANEL
SWITCH
Figure E.3 - Output Rectification, Filtering, Control and Feedback
OUTPUT RECTIFICATION, FILTERING,
CONTROL AND FEEDBACK
The main transformer secondary windings are con-
nected to an SCR/Diode hybrid rectifier bridge. This
three phase AC output from the main transformer sec-
ondary is rectified and controlled through the rectifier
bridge. Output current and voltage are sensed at the
shunt and the output terminals and fed back to the
control board. This feedback information is processed
in the control board. The control board compares the
commands of the output control potentiometer (or
remote control) with the feedback information and
sends the appropriate gate firing signals to the rectifi-
er bridge. The control board also supplies power and
signals to the meter board.
THEORY OF OPERATION
14 PIN
AMPHENOL
TRIGGER AND REMOTE
12VAC
4
115VAC 12VAC
2
V
A
C
MAIN
TRANSFORMER
NOTE: Unshaded areas of Block Logic
Diagram are the subject of discussion
IDEALARC CV-300
OUTPUT
CONTROL
METER
CONTROL BOARD
G
F
A E
E
T
D
E
B
A
S
C
K
+
SHUNT
CAPACITORS
-
OUTPUT
RECTIFIER
The capacitors and the output choke provide the fil-
tering for the controlled DC output of the CV 300
machine. The choke is tapped for supplying either a
soft (high inductance) or a more harsh (low induc-
tance) welding arc.
E-2
F
E
E
D
B
A
C
K
+
OUTPUT
TERMINALS
-
-
CHOKE