Lincoln Electric LN-25 SVM179-B Service Manual page 43

E-5
FIGURE E.5 — OPTIONAL CIRCUITS & DIGITAL DISPLAY BOARD
ELECTRODE
INPUT
CONTACTOR CURRENT TRANSDUCER
INPUT
21
1
14 PIN AMPHENOL
21
DIGITAL
RUN IN
DISPLAY
BOARD
DIGITAL DISPLAY BOARD
(control cable models only)
When the wire feeder is not welding, the left display
shows the wire feed speed.
"in/min" and may be changed to "m/min" through the
setup menu. During welding the left display shows the
average welding current, and will continue to hold the
last value for 5 seconds after the trigger is released.
When the wire feeder is in idle the right display shows
the preset voltage. This voltage will change with dif-
ferent power sources and can be changed through the
setup menu. During welding, the right display shows
the average welding voltage, and will hold the last
value for 5 seconds after the trigger is released.
THEORY OF OPERATION
SOLENOID
POLARITY
V M
CONTROL BOARD
CC
COLD
CV
FEED
The default units are
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
OPTIONAL CIRCUITS
The preflow, burnback, and postflow timer kit gives
control over the shielded gas at the beginning and end
of the weld and prepares the end of the wire for the
next arc start.
The preflow timer range is zero to 10 seconds. Preflow
is used to purge the welding gun with shielding gas and
helps to minimize porosity at the start of a weld.
The burnback timer range is zero to 0.25 seconds.
Burnback controls the additional amount of time the
power source output remains on after the wire drive
has stopped feeding wire.
The postflow timer range is zero to 10 seconds. Use
postflow to protect the weld while it cools.
FEEDPLATE
TACH
GUN
REMOTE
WIRE
VOLTAGE
SPEED
E-5