Control board, Theory of operation – Lincoln Electric SVM143-A User Manual
Page 43
E-3
THEORY OF OPERATION
DH-10
E-3
INPUT RECEPTACLE, CONTROL
BOARD, AND OPERATOR
CONTROLS
The 42 VAC input voltage is applied to the DH-10
through a 9-pin amphenol type receptacle. The
remote control and trigger leads are also accessed
through this 9-pin receptacle. The 42 VAC is rectified
by a full wave bridge and sent to the control board.
This DC voltage is coupled to an onboard switching
power supply. The switching power supply manufac-
tures regulated ±12.8 VDC and +5.0 VDC regulated
supplies for the control board. Refer to Figure E.2.
The control board receives commands from the user
operated controls such as the volts encoder, the wire
feed speed (WFS) encoder, and the keypad. It also
receives feedback information from the active wire
feed head as to the wire feed speed and the arc volt-
age. The control board compares the feedback infor-
mation with the user command signals and generates
the appropriate signals to control wire feed speed, arc
voltage, and gas flow.
The current sensing switch and ground lead protector
are connected to the control board via plug J1. The
current sensing reed switch closes when welding cur-
rent is established which signals the control board to
change from the run-in welding parameters to the pre-
set welding wire feed speed and arc voltage. If the
ground lead protector is activated, the trigger circuit
will be disabled and the WFS display will show “GLP”.
FIGURE E.2 — INPUT RECEPTACLE, CONTROL BOARD AND OPERATOR CONTROLS.
CONTROL BOARD
VOLTS
ENCODER
INPUT
CABLE
RECEPTACLE
RIGHT
WIRE DRIVE
RECEPTACLE
LEFT
WIRE DRIVE
RECEPTACLE
TO GUN TRIGGER
AND
DUAL PROCEDURE
TO GUN TRIGGER
AND
DUAL PROCEDURE
WIRE
DRIVE
MOTOR
WIRE
DRIVE
MOTOR
WFS
ENCODER
DISPLAY
BOARD
CURRENT SENSING
REED SWITCH
GROUND
LEAD
PROTECTOR
KEYPAD
SOLENOID
TACH FEEDBACK
42VDC
TACH FEEDBACK
SOLENOID