Variable Voltage Board, Meter Shunt, Wire Speed; And Remote Output Controls; Variable Voltage Board, Meter Shunt, Wire Speed And Remote Output Controls - Lincoln Electric LN-8 SVM132-A Service Manual

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FIGURE E.3 – VARIABLE VOLTAGE BOARD, METER SHUNT, WIRE SPEED,
REMOTE
OUTPUT
CONTROL
#75
#76
#77
#32
INPUT
RECEPTACLE
#31
#2
&
#4
C
O
N
T
A
C
T
O
R
CONTROL
OPTIONAL
BURNBACK
VARIABLE VOLTAGE
BOARD, METER SHUNT,
WIRE SPEED AND
REMOTE OUTPUT
CONTROLS
The optional variable voltage board
enables the LN-8 to be used with a con-
stant current power source. The vari-
able voltage board monitors the arc
voltage via leads #21 and #567 and
modifies the wire feed speed according
to arc voltage variations and require-
ments.
The wire speed control dictates to the
control board the directives of the
NOTE: Unshaded areas of block logic diagrams are the subject of discussion.
THEORY OF OPERATION

AND REMOTE OUTPUT CONTROLS

#21
VARIABLE VOLTAGE
WIRE FEED
SPEED CONTROL
CIRCUIT
BREAKER
#32A
2 OHMS
#531
FUSE
BOARD
REED
GLP
SWITCH
ELECTRODE
#567
METER
BOARD
SHUNT
ARMATURE
CONTROL
BOARD
#3
2
A
RELAY
BOARD
WIRE
TRIGGER INTERLOCK
FEED
TRANS. SWITCH
SWITCH
operator. The control board adjusts the
armature voltage applied to the wire
feed motor to change the motor speed.
The remote output control permits
power source control from the LN-8
unit. The remote control is coupled to
the welding power source via leads #75,
#76, and #77 through the input
receptacle.
The electrode meter shunt, which is
connected to and also in series with the
gun connector block, senses the weld-
ing current and arc voltage. This infor-
mation is used by the variable voltage
board and also the optional meter kit.
LN-8
WIRE
THERMAL
FEED
CIRCUIT
MOTOR
BREAKER
FIELD
GUN
CABLE
RECEPTACLE
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