AUTO ARC 120 - OVERHEATING AND SHORT CIRCUIT SHUTDOWN; DRIVE ASSEMBLY CLEANING AND REPAIR

B.
Overheating
Thermostat
TP1
protects
the
unit
from
damage
due
to
overheating.
If
main
transformer
Ti
gets
too
hot,
TP1
opens
and
weld
output
stops.
The
fan
keeps running
to
cool
the
transformer. Wait several
minutes
before
trying
to
weld.
C.
Short
Circuit
Shutdown
If
contact
tube
is
shorted
and sticks
to
workpiece,
the unit
shuts
down,
but fan
runs.
To
resume
operation,
release
gun
trigger,
turn
Off
unit,
and
remove
contact
tube from
workpiece.
Check
contact
tube
and
replace
if
damaged.
Turn
On
unit
to
continue
operation.
5-3.
Cleaning
Or
Repairing
Drive
Assembly
I
.~
READ
SAFETY
BLOCKS
at
start
of
Section
5
before
proceeding.
Tools Needed:
5/6~1
~:-
Turn
Off
and
unplug
unit.
1
Wire
Spool
2
Gun
Contact Tube
Cutwelding
wire
off
at
contacttube.
Retract
wire
onto
spool
and
secure.
3
Pressure
Roll
Arm
4
Cotter
Pin
5
Pin
6
Screw
7
Bearing
Remove
bearing
as
shown. Install
new
bearing
and
secure
with
screw.
Reinstall
arm onto
pin
and
secure
with
cotter
pin.
8
Setscrew
9
Smooth
Groove For
Hard
Wire
10
Drive
Roll
Remove
drive
roll
as
shown.
Use
a
wire brush
to
clean
drive
roll.
Push
drive
roll
onto
shaft
with
desired
groove
in.
Turn
drive roll
so
one
setscrew
faces
flat
side
of
shaft,
and
tighten
both
setscrews.
11
Knurled
Groove For Flux-
Cored
Wire
12
Wire Inlet
Guide
Remove
guide by
pressing
on
barbed
area or
cuttIng
off
one
end
near
housing
and
pulling
it
out
of
hole. Push
new
guide
into hole
from
rear
until
it
snaps
in
place.
Thread
welding
wire
(see
Section
3-4).
Close
door.
Ret.
ST-151
357IST-149266~B
Figure
5-3.
Cleaning
Or
Repairing
Drive
Assembly
OM-151
015
Page
11