Input Power - Lincoln Electric LN-25 SVM179-B Service Manual

E-3
ELECTRODE
INPUT
CONTACTOR CURRENT TRANSDUCER
INPUT
21
1
14 PIN AMPHENOL
21
DIGITAL
RUN IN
DISPLAY
BOARD

INPUT POWER

The DC input voltage is applied from the power source
via the electrode cable and the work sensing lead on
the across the arc model. With the control cable model
24 to 42VDC is supplied from the power source via the
control cable and the work sense lead.
This voltage is applied through a bridge rectifier and an
analog voltmeter (across the arc), or digital meter (con-
trol cable) and then is supplied to the control board.
The control board the regulates and disperses the var-
ious supply voltages needed for machine operation.
THEORY OF OPERATION
FIGURE E.3 — INPUT POWER & TRIGGER CIRCUIT
SOLENOID
POLARITY
V M
CONTROL BOARD
CC
COLD
CV
FEED
NOTE: Unshaded areas of Block Logic
Diagram are the subject of discussion
LN-25™ PRO
67
TIMER OPTION
MOTOR
MOTOR
OVERLOAD
ARMATURE
TACH FEEDBACK
GUN TRIGGER
TRIGGER GAS
INTERLOCK PURGE
TRIGGER CIRCUIT
When the gun trigger is closed, the control board is sig-
naled to apply armature voltage to the drive motor and
to activate any auxiliary circuits that may be incorpo-
rated within the LN-25PRO.
Trigger interlock is used for long welds. When an arc
is established the trigger can be released. To stop
welding, the gun trigger is pulled again, and when it is
released the second time, the welding power source
output turns off and the wire speed stops.
FEEDPLATE
TACH
GUN
REMOTE
WIRE
VOLTAGE
SPEED
E-3