Lincoln Electric PRECISION TIG SVM186-A Service Manual page 74

F-34
TYPICAL OUTPUT VOLTAGE WAVEFORM - MACHINE LOADED
HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.
• Perform all voltage and waveform checks with high frequency circuit OFF.
• Perform High Frequency Disable Procedure.
____________________________________________________________________
TROUBLESHOOTING AND REPAIR
DC TIG MODE
CAUTION
MACHINE LOADED TO 180 AMPS AT 16VDC.
This is the typical DC (+) output voltage wave-
form generated from a properly operating
machine. Note that each vertical division repre-
sents 10 volts and that each horizontal division
represents 2 milliseconds in time. The machine
was loaded with a resistance grid bank. The grid
load meters read 180 amps and 16VDC
Note: Scope probes connected at machine out-
put terminals: (+) probe to electrode, (–) probe to
work.
SCOPE SETTINGS
Volts/Div.....................50V/Div.
Horizontal Sweep .....2 ms/Div.
Coupling.............................DC
Trigger.........................Internal
PRECISION TIG® 225
2ms
F-34
50 volts
0 volts