Lincoln Electric Precision TIG 375, Service Manual, Page: 88 / 143

F-42 F-42
PRECISION TIG 375
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TROUBLESHOOTING & REPAIR
0V
5 ms 20V
TYPICAL AC VOLTAGE WAVEFORM - MACHINE LOADED TO 2 AMPS
AC - TIG MODE
HIGH VOLTAGE/ HIGH FREQUENCY can damage test equipment.
Perform all voltage and waveform checks with high frequency circuit OFF.
Perform High Frequency Disable Procedure.
This is the typical AC output voltage
waveform generated from a properly
operating machine. Note that each ver-
tical division represents 20 volts and
that each horizontal division represents
5 milliseconds in time.
NOTE: Scope probes connected at
machine output terminals: (+) probe to
electrode, (-) probe to work.
Volts/Div......................20V/Div.
Horizontal Sweep......5 ms/Div.
Coupling..............................DC
Trigger..........................Internal
SCOPE SETTINGS
AC BALANCE CONTROL IN “AUTO”
OUTPUT CONTROL AT MINIMUM.