Troubleshooting & repair, 50 volts 2ms ch1 – Lincoln Electric SQUARE WAVE TIG 255 SVM100-A User Manual
Page 80
SQUARE WAVE TIG 255
F-39
TROUBLESHOOTING & REPAIR
ABNORMAL OPEN CIRCUIT VOLTAGE - AC STICK MODE
ONE OUTPUT SCR NOT FUNCTIONING
CAUTION
HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.
• Perform all voltage and waveform checks with high frequency circuit OFF.
_____________________________________________________________________
0 volts
50 volts
2ms
CH1
This is NOT the typical AC output voltage
waveform. One output SCR is not function-
ing. Note the “gap” in the waveform. One
SCR gate was disconnected to simulate an
open or non-functioning output SCR. Each
vertical division represents 50 volts and
each horizontal division represents 2 mil-
liseconds in time.
Note: Scope probes connected at machine
output studs: (+) probe to electrode, (–)
probe to work.
Volts/Div................................50 V/Div.
Horizontal Sweep .................2 ms/Div.
Coupling .........................................DC
Trigger .....................................Internal
SCOPE SETTINGS