Lincoln Electric NA-3 Service Manual page 72

F-7
Troubleshooting Guide –
of specified components and when troubleshooting specific circuits.
PROBLEMS
(SYMPTOMS)
The wire will NOT inch down but
does inch up properly. When the
"Start" switch is pressed, the wire
feeds down properly.
NOTE: When using DC-400,
CV-400, and Pulse Power 500
power sources, diode kits must be
installed if auto stop circuit is
required. If auto stop circuit is not
required, move jumper on variable
voltage board to pin "L". See wiring
diagram.
The wire will NOT inch down but
inches up properly. When the
"Start" switch is pressed, the wire
does not feed.
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely,
contact the Lincoln Electric Service Department for technical troubleshooting assistance before you proceed.
Call 216-383-2531 or 1-800-833-9353.
TROUBLESHOOTING AND REPAIR
See the Wiring Diagrams Section for location
POSSIBLE AREAS OF
MISADJUSTMENT(S)
FUNCTION PROBLEMS (Continued)
1. While pressing the "Inch
Down" switch, observe light 2J.
It should be lit. If not, the "Inch
Down" switch (S4) or associat-
ed wires may be faulty. See
wiring diagram.
2. If the NA-3 is in the constant
voltage (CV) mode and light 2J
does light, the logic board may
be faulty.
3. If troubleshooting the NA-4, the
variable voltage board may be
faulty. Make sure the switch is
in the "VV" position and the
jumper wire is connected to pin
"L".
1. Press the "Inch Down" switch
and observe light 1B on the
control board. If light 1B is lit
and the motor does not acti-
vate, the control board may be
faulty.
CAUTION
NA-3 AND NA-4
Observe Safety Guidelines
detailed at the beginning of this manual.
RECOMMENDED
COURSE OF ACTION
1. If the NA-3/NA-4 is in the vari-
able voltage (VV) mode and a
variable voltage board is
installed, disconnect lead #21
from the terminal strip. Turn
on input power and while
pressing the "Inch Down"
switch, observe light 3A. If
light 3A does NOT light, the
variable voltage board may be
faulty. Replace board and
reconnect lead #21.
If light 3A does light, with lead
#21 disconnected, the resis-
tance across leads #21 and #67
is too low. The resistance must
be above 500 ohms. The low
resistance could be caused by
the following:
-A lead or object external to the
power source or NA-3/NA-4
causing a low resistance
between leads #21 and #67.
-A non-Lincoln Electric power
source not designed with the
required impedance.
-A defective power source.
1. If light 1B does NOT light when
the "Inch Down" switch is
pressed, measure the DC
voltage from lead #586 to lead
#539 while pressing the "Inch
Down" switch. Normal voltage
is 12 to 15 VDC.
-If normal voltage is indicated,
the control board may be faulty.
-If normal voltage is not pre-
sent, the logic board may be
faulty.
F-7