OPERATING INSTRUCTIONS
B-11
B-11
NA-5
In some cases, it is also possible to hold the
“Actual” button pressed while starting the
arc. Before the NA-5 shuts down, the actual
arc voltage can be read on the digital meter.
Comparing this reading to the “Set” reading
will tell what change in the range controls of
the power source are required so it can
supply the desired voltage. Should the
meter read zero, check the NA-5 sensing
leads (#21 and #67) connections. Should
the meter read negative (-) voltage, the
polarity connections or settings at the NA-5
or power source are wrong.
This same general procedure can be used
on the other power sources. For example,
if the NA-5 keeps shutting down and the
other possible causes have been checked,
adjust the “Set” voltage higher and/or lower
than the desired voltage. If the NA-5
continues to weld at one of these voltages,
it can be determined what change in the
range controls of the power source are
required so it can supply the desired voltage.
COLD START CIRCUITRY
NA-5 controls above Code 8300 contain
circuitry added to the voltage PC board to
facilitate the “cold starting” features of these
units.* This circuitry senses the voltage
present between the electrode and work, via
leads #67 and #21, and permits normal wire
feed if this voltage exceeds approximately
6.5 VDC. However, if this voltage level is
not exceeded, or drops below approximately
3.5 VDC, the “Auto Stop” activates while
inching down or electrode backup occurs if
the arc start circuit has been initiated.
*Units below Code 8300 can be provided with the cold
start circuitry by replacing the old L-6257 voltage board
with the new G-1556 voltage board. This new board
will mount and connect in the same manner as the old
board, except the third harness connector (previously
connected to a jumper plug) must be connected to the
lower receptacle of the new voltage board.
NOTE: HI-FREQ starting cannot be used
with converted units below Code 8300.
A. Auto Stop
When the “Inch Down” button is pressed, a
low-level DC voltage signal is applied
between the electrode and work which
permits the wire to inch down normally.
When the electrode makes electrical contact
with the work, it shorts out this signal
causing the wire feed to automatically stop
and the flux solenoid to activate until the
“Inch Down” button is released. The “Inch
Up” button is not affected by this circuit.
B. Electrode Backup
If while starting or welding the electrode
stubs or shorts to work, the resulting loss of
arc voltage will cause the electrode to
momentarily back up until the arc voltage is
re-established and then change back to the
normal feed direction.
NOTE: The “cold starting” circuitry will
cause the NA-5 to feed in the wrong
direction when the “Start” button is pressed
if the “Actual” arc voltage, as read on the
NA-5 voltmeter, does not exceed typically
about 6.5 volts. Usual causes for the
situation are:
1. No wire loaded through the NA-5
head and nozzle assembly (except
when using the K148 Contact
Nozzle).
2. No power source weld cable
connection to the NA-5 head or work.
3. Incorrect electrode polarity
connections at the NA-5 or power
source.
4. Little or no output voltage from the
power source.
5. An open voltage sensing lead #67 or
#21 to the NA-5 control box or a
blown 1/8 amp fuse on a voltage PC
board built since 1983.
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