Lincoln Electric IM351 LN-7 GMA Wire Feeder - Manual (Page 42)

B-12 OPERATION B-12
ACCELERATION SETTING
The LN-7 and LN-7 GMA can be configured for
optimum starting for different procedures by selecting
between two speeds of controlled wire acceleration. As
shipped from the factory, the LN-7 and LN-7 GMA
models are set for fast acceleration. Fast acceleration
is typically the best for most smaller wire procedures.
Slow acceleration may be more desirable for long
stickout applications, or if a larger diameter electrode is
being used.
Acceleration is set on the control PC board. To gain
access to the control PC board, make certain the input
power is off and remove the side cover on the control
side of the LN-7 or LN-7 GMA. To change the
acceleration on earlier control PC boards, reconnect
the jumper to “F” (Fast) or “S” (Slow). Later control PC
boards use a DIP switch (S101). S101 has 8 circuits
(switches); only circuit #1 is used. Set circuit #1 in the
“F” position for fast acceleration or in the “S” position
for slow acceleration. See Figure B.7.
FIGURE B.7 – ACCELERATION SETTING
(LATER CONTROL PC BOARDS).
WIRE SPEED AND VOLTAGE
ADJUSTMENT
Use only constant voltage power type sources. If using
a multiple process power source, be sure it is set for
constant voltage output per instructions in the manual
for the power source.
Set the power source polarity switch or properly
connect the electrodes and work leads for the correct
electrode polarity. If the wire feeder is equipped with an
optional meter kit, set the meter polarity switch to the
proper working polarity.
Set the voltage using the control on the power source
or the optional remote voltage control, if used. Set the
open circuit voltage to approximately 2 volts higher
than the desired procedure voltage. The final setting
must be made according to the arc voltage while
welding.
The wire speed control on the front of the wire feeder,
Figure B.8, has a dial that is calibrated directly in
inches per minute. Set the control for the desired
procedure wire speed.
FIGURE B.8 – SETTING WIRE SPEED.
LN-7 & LN-7 GMA
S101
F S
UNUSED
CIRCUITS
CIRCUIT #1
WIRE
SPEED
CONTROL