Theory of operation, Control board, gun trigger and wire drive motor – Lincoln Electric POWER MIG 11521 User Manual
Page 36
THEORY OF OPERATION
E-4
E-4
Power MIG® 215XT
CONTROL BOARD, GUN
TRIGGER AND WIRE DRIVE
MOTOR
When the control board receives an activation
command from the trigger circuit the control board
supplies 12VDC which activates the gas solenoid and
output contactor. It also supplies 2 to 29 VDC
(depending on the wire speed setting) to the wire drive
motor. The control board monitors the motor’s tach
feedback signals and compares these to the wire
speed control setting. The proper armature voltage is
then applied to the wire drive motor. The drive motor
speed is thus controlled which in turn regulates the
electrode wire feed speed through the gun.
FIGURE E.2 - OPTIONAL CIRCUITS
Two self re-setting thermostats are included in the
trigger circuitry. If either of these thermostats would
“open” due to excessive heat, the trigger circuit would
be interrupted and the machine’s output and the wire
feed would be disabled. The board also contains
overload protection circuitry which protects the drive
motor from excessive current draw.
The Power MIG® 215XT is equipped with an adapter
panel and switch to allow operation of a spool gun for
feeding aluminum wires.
LINE
SWITCH
RECONNECT
PANEL
FAN
MOTOR
CONTROL BOARD
GAS
SOLENOID
WIRE
SPEED
CONTROL
SPOOL
GUN
SWITCH
WIRE
DRIVE
MOTOR
TACH
FEEDBACK
GUN TRIGGER
+
-
OUTPUT DIODE
BRIDGE
+
-
NEGATIVE
TERMINAL
CONTACTOR
CONT
ACT
OR
CONTROL
TAP SELECTOR
SWITCH
OUTPUT
CHOKE
POSITIVE
TERMINAL
TRANSFORMER
THERMOSTAT
OUTPUT BRIDGE
THERMOSTAT
MAIN
TRANSFORMER
OUTPUT
CAPACITORS
GUN
ASSEMBLY
115V
RECEPTACLE
CIRCUIT
BREAKER
27.8 V
AC
NOTE: Unshaded areas of Block Logic
Diagram are the subject of discussion