Circuit Protection; Avoiding Ground Lead Protector (Glp) Activation; Drive Roll Installation; Changing Drive Rolls For Two-Roll Wire Feeders - Lincoln Electric SVM 106-A Service Manual

B-4

CIRCUIT PROTECTION

A manual reset circuit breaker protects the AC supply
line and the wire feeder from overloads, usually caused
by excessive wire drag or other wire feed problems. To
reset the circuit breaker, raise the cover of the wire
drive compartment and push the white button on the
side of the control box above the drive rolls. If the
circuit breaker trips again, refer to the Troubleshooting
Section.
The LN-7 GMA also includes a Ground Lead Protector
(GLP) circuit and fuse in the 2-4 contactor circuit. See
the Theory of Operation Section for a description of
these circuits.
AVOIDING GROUND LEAD
PROTECTOR (GLP) ACTIVATION
DO NOT allow the electrode to contact the case of the
wire feeder or the uninsulated part of the wire reel
stand when the gun trigger is activated.
Be sure that all work lead connections to the work
make tight metal-to-metal contact.
DO NOT allow excess input cable or work cable to be
placed closer than three feet from the wire feeder.
DO NOT coil excess input cable assembly or use a
coiled assembly as shipped from the factory. Instead,
loop the excess cable length back and forth in three to
six foot straight lengths. Coiling the input cable results
in a transformer action between the electrode
conductor cable and the ground lead in the
multiconductor control cable. This transformer action
can cause a current to flow in the ground lead which
will falsely activate the GLP circuit.
To reset the GLP circuit, press the red button above the
drive rolls and to the left of the circuit breaker.
LN-7 GMA WIRE FEEDER
OPERATION

DRIVE ROLL INSTALLATION

CHANGING DRIVE ROLLS FOR TWO-
ROLL WIRE FEEDERS:
To change drive rolls on a two-roll wire feeder, refer to
Figure B.2 and perform the following steps:
1. Rotate the latch knob on the quick release arm.
2. Remove the hex head screw and clamping collar.
Remove the drive roll from the shaft. On new
machines, remove the tape and the drive key.
3. The new roll to be installed is stamped for the size to
be fed. An "A" after the size indicates aluminum wire.
Remove the rolls from the kit and wipe them clean.
Wipe the output shaft and locating shoulder clean.
4. Use the drive key, clamping collar, and hex head
screw to install the roll on the output shaft. Certain
size drive rolls consist of two roll halves, and may
contain a spacer. If the drive roll you are installing
contains a spacer, the spacer fits between the two
halves of the drive roll. Tighten the hex head screw.
5. Back out the guide tube clamping screws.
Remove the old guide tubes, if installed.
6. Insert the outgoing guide tube (the one with the
plastic insert) into the front hole. If the guide tube
has a non-symmetrical chisel end, the larger
radius must face the drive roll. See Figure B.2.
Push the guide tube back as far as it will go and
tighten the clamping screw. Insert the incoming
guide tube as far back as it will go and tighten the
clamping screw. The clamping screws are dog
points. When the guide tubes are properly
installed these dog points will lock into the annular
grooves in each of the guide tubes.
7. Set the idle roll pressure as detailed in the Idle
Roll Pressure Setting procedure detailed later in
this section.