Component Location And Access; Spark Gap Adjustment - Lincoln Electric SQUARE WAVE TIG 275 IM609-B Operator's Manual

D-2

COMPONENT LOCATION AND ACCESS

Control PC Board:
Remove the left case side. Use a 3/8" Nut Driver or
other suitable tool.
Note: The Case side can be removed while roof is in
place, as long as the three screws which secure the
roof to the case side are removed. The PC Board is
mounted on left divider assembly and can be removed
with a phillips head screwdriver.
Display PC Board, Arc Starter/Bypass PC
Board:
Remove the roof and both case sides. Use a 3/8" Nut
Driver or other suitable tool.
located on the inside case front of the machine.
Spark Gap Assembly, High Voltage
Transformer:
Remove the right case side. Use a 3/8" Nut Driver or
other suitable tool. The high voltage transformer is
mounted to the base. The spark gap assembly is locat-
ed on the inside case front.
Main Rectifier:
Remove the roof and both case sides. Next, remove
the case back assembly. Use a 3/8" Nut Driver or other
suitable tool. The main rectifier is mounted to the main
transformer, in front of the cooling fan.
MAINTENANCE
These PC Boards are
SQUARE WAVE TIG 275

SPARK GAP ADJUSTMENT

The spark gap is set at the factory to a gap of 0.015
inches (0.4 mm). This setting is adequate for most
applications. Where less high frequency is desired, the
setting can be reduced to 0.008 inches (0.2 mm).
To adjust the spark, first be sure that the input power to
the machine is 'OFF' AT THE DISCONNECT SWITCH
OR FUSE BOX. The high voltages developed in the
high frequency circuit can be lethal. Next, remove the
right case side. Use a 3/8" Nut Driver or other suitable
tool. Disconnect the two push on wires to the spark
gap blocks and pull back the dust shield. Check the
spark gap spacing with a feeler gauge. If adjustment is
required, pull off one of the two leads going to the alu-
minum spark gap blocks. Adjust the gap by loosening
the Allen head screw, reset the gap and tightening the
screw in the new position. Replace the dust shield and
the two leads removed earlier. Reinstall the case side.
FIGURE D.1 SPARK GAP
RIGHT SIDE VIEW OF MACHINE
D-2
.015 Spark Gap