Lincoln Electric LN-25 PRO DUAL POWER Service Manual page 49

E-7
ELECTRODE
INPUT
INPUT
21
14 PIN AMPHENOL
REMOTE
VOLTAGE
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 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. Us postflow to protect to
protect the weld while it cools.
THEORY OF OPERATION
FIGURE E.7 - OPTIONAL CIRCUITS
CURRENT TRANSDUCER
CONTACTOR
SOLENOID POLARITY
SP1
CONTROL BOARD
POWER
SUPPLY
COLD CC
FEED CV
RUN IN
NOTE: Unshaded areas of Block Logic
Diagram are the subject of discussion
LN-25™ PRO DUAL POWER
67
TIMER OPTION
MOTOR
MOTOR
OVERLOAD
ARMATURE
TACH FEEDBACK
GUN TRIGGER
TRIGGER
GAS
INTERLOCK
PURGE
E-7
FEEDPLATE
TACH
GUN
WIRE
SPEED