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E-4
TROUBLESHOOTING
E-4
LN-742 & LN-742H
Observe all Safety Guidelines detailed throughout this manual
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact your
Local Lincoln Authorized Field Service Facility for technical troubleshooting assistance before you proceed.
CAUTION
PROBLEMS
(SYMPTOMS)
POSSIBLE
CAUSE
RECOMMENDED
COURSE OF ACTION
The LN-742 voltmeter does not
function or read correctly when the
actual arc voltage is present. The
wire feeder is feeding wire correct-
ly.
The LN-742 shuts down while
welding and the HXX symbol
appears on the display.
The display and/or indicator lights
do not change when the arrow or
select keys are pressed.
The arrow keys do not change the
welding wire feed speed.
1. Make sure the polarity switch on
the Lincoln welding power
source is in the correct position
for the welding process.
2. Check or replace the control
cable. Check the continuity
(zero ohms) of leads #21 and
#67.
1. Check for mechanical restric-
tions in the wire feed path.
1. Make sure the control cable is
connected to the welding power
source correctly.
2. Check the 42 VAC fuse or cir-
cuit breaker in the welding
power source.
1. If a remote control unit is con-
nected to the LN-742 the arrow
keys will not change welding
wire feed speed. Use the WFS
pot on the remote control unit or
disconnect the remote control
unit and use the arrow keys.
If all recommended possible areas of
misadjustment have been checked
and the problem persists, Contact
your local Lincoln Authorized
Field Service Facility.