Lincoln Electric SQUARE WAVE TIG 355 Service Manual page 43

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5. If any voltage is present, DISCHARGE EACH INDI-
VIDUAL CAPACITOR as follows:
a. Obtain a 500 Ohm resistor. Grip the 500 ohm
resistor with insulated gloves and insulated
gripping pliers and hold the resistor across the
terminals on each capacitor for 20 seconds.
See Figure D.1.
b. With the volt/ohmmeter, recheck each capaci-
tor for voltage.
6. After all the capacitors are discharged completely,
check for broken capacitor leads or an open prima-
ry winding on the main transformer, which would
have prevented the capacitors from discharging
normally.
ROUTINE AND PERIODIC
MAINTENANCE
WARNING
To avoid receiving a high frequency shock, keep elec-
trode holders, TIG torches and cable insulation in good
condition.
1. Disconnect power supply lines to the machine
before performing periodic maintenance.
FIGURE D.1 – POWER FACTOR CAPACITOR DISCHARGE DETAILS
MAINTENANCE
2. Periodically blow out dust and dirt from the inside of
the machine with a low pressure air system. Be
sure to clean the following components thoroughly.
See Figure D.2 for their location.
• Main transformer
• Output terminals (located on case front)
• Polarity switch (located on case front)
• Rectifier assembly
• Control box assembly
• Spark gap assembly
• Protection PC board
3. Inspect the welder output terminals and control
cables for fraying, cuts, and bare spots.
4. Inspect the spark gap spacing at regular intervals.
To access the spark gap, remove the nameplate
located on the lower right section of the output
panel. Maintain the gap marked on the machine
cover plate. Please note the following:
• If more intensity is needed than is available with
the "High Frequency" set to MAXIMUM, increase
the spark gap according to the intervals on the
cover plate. (To minimize RFI problems, use the
smallest possible spark gap setting that still pro-
vides good welding.)
• Do not dress or refinish the spark gap contacts.
Replace the electrodes if the contact surfaces
become irregular or completely eroded.
5. The fan motors have sealed ball bearings and
require no maintenance.
SQUARE WAVE TIG 355
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