Wire Drive Motor And Feedback - Lincoln Electric WIRE-MATIC 255 SVM 119-A Service Manual

E-4
MAIN
LINE
TRANSFORMER
SWITCH
RECONNECT
FAN
MOTORS
WIRE DRIVE MOTOR AND
FEEDBACK
The wire drive motor is controlled by the control board.
A motor speed feedback signal is generated at the
motor tach and sent to the control board. The control
board compares this feedback signal with the com-
mands set forth by the Wire Speed Control poten-
tiometer and sends the appropriate armature voltage
to the wire drive motor. The drive motor speed is thus
controlled which in turn regulates the electrode wire
feed speed through the gun.
THEORY OF OPERATION

WIRE DRIVE MOTOR AND FEEDBACK

WIRE GAS
SPEED SOLENOID
ARC
VOLTAGE
CONTROL BOARD
G
A
T
E
S
I
G
N
A
L
SCR
RECTIFIER
Figure E.5 - Wire Drive Motor and Feedback.
NOTE: Unshaded areas of Block Logic
Diagram are the subject of discussion
WIRE-MATIC 255
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
E-4