Lincoln Electric POWER-ARC 4000 SVM103-A Service Manual page 66

F-25
RHEOSTAT REMOVAL AND REPLACEMENT
See Figure F.7 for steps 3 - 9.
PROCEDURE
1. Remove the spark plug wire.
2. With the 5/16" nut driver, remove the 4
sheet metal screws that hold the top cover
to the control box. Remove the top cover.
3. With the small slot head screw driver,
loosen the screw that holds the knob to
the rheostat shaft. The shaft has a flat for
locating the knob at reassembly.
4. With a 9/16" open or box end wrench,
remove the nut that holds the rheostat to
the control panel. Support the rheostat
with your hand as you turn the nut. There
is a shake-proof washer under the nut.
5. Pull the rheostat back out of the control
panel and lay it out on its wires to loosen
the nuts that hold them.
6. With the 5/16" open or box end wrench,
remove the brass nuts from the wire termi-
nals. Support the terminals as you turn
the wrench to avoid ripping the terminals
from their foundations.
locations for reassembly.
Note: The brass screws are double-nutted
with a shake-proof star washer under the
screw head.
POWER-ARC 4000
TROUBLESHOOTING & REPAIR
FIGURE F.7 - RHEOSTAT REMOVAL
Note the wire
7. To reinstall the rheostat, replace each of
the brass screws. Place a shake-proof
star washer under the head, insert the
screw into the rheostat and tighten down
one nut. Replace the appropriate wires
and tighten down the second nut. Again,
support the terminals as you turn the
wrench to avoid ripping the terminals
from their foundations.
8. Reassemble the rheostat to the front of
the control panel. Line up the locating
tab on the rheostat with the slot on the
control panel hole.
9. Reassemble the shake-proof star washer
and nut and tighten securely with the
9/16" wrench.
10. Locate the flat spot on the shaft, line up
the knob locking screw, push the knob
onto the shaft and tighten the screw with
the small slot head screw driver.
11. Check the rheostat knob for proper rota-
tion, minimum to maximum.
12. Replace the top cover of the control box
and tighten the 4 sheet metal screws with
the 5/16" nut driver.