Keypad, Display Board, Control Board, Reed Switch, Drive Motor And Tach Feedback - Lincoln LN-742 Service Manual

E-4
FIGURE E.3 – KEYPAD, DISPLAY BOARD, CONTROL BOARD,
42VAC
42VAC
INPUT CABLE
RECEPTACLE
KEYPAD, DISPLAY BOARD,
CONTROL BOARD, REED
SWITCH, DRIVE MOTOR,
AND TACH FEEDBACK
The control board receives commands from
the keypad via the display board. The control
board compares these commands with the
THEORY OF OPERATION
REED SWITCH, DRIVE MOTOR AND TACH FEEDBACK.
KEYPAD
AC DC+
CONTROL BOARD
AC DC-
CONTACTOR CONTROL
LN-742 & LN-742H
DISPLAY
PC BOARD
FEEDBACK
GAS GUN TRIGGER
SOLENOID RECEPTACLE
information it receives from the tach
feedback and current sensing reed switch
and sends the appropriate signals to the wire
drive motor. Thus the wire is fed at the
correct speed and at the correct time
dependent upon the commands issued from
the keypad. The display board exhibits the
commands set forth by the keypad as well as
displays the actual arc voltage.
E-4
CURRENT
SENSING
REED
SWITCH
DRIVE
MOTOR
TACH