Maintenance; Service Procedures; Spark Gap Adjustment; Under Cooler Service - Lincoln Electric PRECISION TIG 375 Service Manual

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SERVICE PROCEDURES

Operation of the Precision TIG should be trouble-free
for the life of the machine. Should a malfunction occur,
however, the following procedures will be useful to
trained service personnel with experience in repairing
arc welding equipment:
COMPONENT ACCESS
The following components are accessible for routine
set up and periodic service without requiring removal
of the case sides or roof:
• Input Reconnect Panel (refer Section A) is located
behind a removable panel on the rear of the left case
side. Remove the two screws (with a screwdriver or
a 3/8"/ 9.5mm hex driver) on the bottom corners of
this panel to remove it.
• Control Box components and PC Boards (refer
Section B-6) are located behind the front control
panel. Remove the two screws (with a screwdriver or
a 3/8"/ 9.5mm hex driver) on the top corners of this
panel to swing it down.
• Hi-Freq. Spark Gap Assembly (refer Spark Gap
Adjustment) is located behind a removable panel on
the rear of the right case side, under the torch box.
Remove the screw (with a screwdriver or a 3/8"/
9.5mm hex driver) on the bottom center of this panel
to remove it.

SPARK GAP ADJUSTMENT

The spark gap is set at the factory to a gap of 0.015
inches (0.4 mm) See Figure C.1. This setting is ade-
quate for most applications. Where less high frequency
is desired, the setting can be reduced to 0.008 inches
(0.2 mm).
WARNING
Use extreme caution when working with the high
frequency circuit. The high voltages developed can
be lethal. Turn the input power off using the dis-
connect switch or fuse box before working inside
the machine. This is particularly important when
working on the secondary circuit of the high volt-
age transformer (T3) because the output voltage is
dangerously high.
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MAINTENANCE

Note: In highly dirty environments where there is an
abundance of conductive contaminants, use a low
pressure air stream or a firm piece of paper to clean
out the spark gap. Do not disturb the factory gap set-
ting.
To check the spark gap:
1. Turn the input power off per above.
2. Remove the access panel on the right case side
(See Component Access).
3. Check the spark gap spacing with a feeler gauge.
If adjustment is required:
1. Adjust the gap by loosening the Allen head screw
on one of the aluminum blocks, reset the gap and
tighten the screw in the new position.
If spark gap is correct:
1. Reinstall the access panel on the right case side.
UNDER-COOLER SERVICE
The required maintenance and service instructions for
the Under-Cooler are provided in the operator's manu-
al (IM723) provided with the Under-Cooler Cart.
PRECISION TIG 375
FIGURE C.1 SPARK GAP
.015 Spark Gap
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