Lincoln Electric NA-5N Service Manual page 31

B-8
Wire Feed Motor Acceleration
The NA-5 has two different speeds of
controlled wire feed motor acceleration. As
shipped, the unit is connected for fast
acceleration which is best for most
applications. To change to the slower
acceleration, turn off all input power to the
NA-5 control box. Open the control box.
Locate the Control PC Board mounted on
the back of the box in the lower right hand
corner. Change the jumper plug from the "F"
pin to the "S" pin as shown in Figure B.2.
FIGURE B.2 – ACCELERATION
Burnback and Electrode Backup
The primary consideration in setting the arc
stopping sequence is to prevent the
electrode from sticking in the puddle. This
is easily done with the machine as shipped.
OPERATING INSTRUCTIONS
WARNING
ELECTRIC SHOCK
can kill.
• Turn off input power to
the welding power source
using the disconnect
switch before working on
this equipment.
JUMPER PLUGS.
JUMPER
PLUG
NA-5
The standard stopping sequence when the
optional "Crater Controls" are not used is as
follows:
1. Press the "Stop" button.
2. The wire feed motor stops and the
"Burnback Time Delay" starts.
3. The arc continues to burn the
electrode back from the puddle until
the arc goes out or the time set on the
thumbwheel switch elapses. This
control should be set for just enough
burnback time to prevent crater
sticking.
There are two other ways this circuit can be
connected. One will cause the wire to
retract* with a contactor drop out delay at
the end of the weld. The second will cause
the wire to retract* during burnback time,
and there will be no contactor drop out delay
at the end of the weld. If either one of these
alternate methods of stopping the weld is
desired, the connections on the logic board
can be easily changed.
To change the stopping sequence, turn the
input AC power off at the power source,
remove the screw holding the inner panel,
and swing the panel open. Change the
connections (older models) or switch
positions (newer models) on the logic board
as shown in Table B.2.
Optional "Crater Controls"
This option is recommended for applications
where the ending bead size must be
controlled, applications when the crater must
be filled, roundabouts, and any other welds
where the end overlaps the start.
When the "Stop" button is pressed, the
machine welds at the wire speed and
voltage set by the "Crater Controls" until the
time set on the thumbwheel switch elapses.
The circuit then automatically switches to the
arc stopping sequence described above.
NOTE: Setting crater time to 0.00 seconds
will give zero crater time; however, the
crater settings will be active during
burnback time until the arc goes out.
* Wire will retract at weld mode speed (or crater mode
speed, if installed) until the arc goes out and then retract
at strike mode speed for the remainder of burnback
time.
B-8