Troubleshooting & repair, 50 volts 2ms ch1 – Lincoln Electric SQUARE WAVE TIG 255 SVM100-A User Manual
Page 79
SQUARE WAVE TIG 255
F-38
TROUBLESHOOTING & REPAIR
ABNORMAL OPEN CIRCUIT VOLTAGE - DC 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 DC (+) output volt-
age waveform. One output SCR is not
functioning. Note the “gap” in the wave-
form. One SCR gate was disconnected to
simulate an open or non-functioning output
SCR. Each vertical division represents 50
volts and each horizontal division repre-
sents 2 milliseconds in time.
Note: Scope probes connected at machine
output studs: (+) prove to electrode, (–)
probe to work.
Volts/Div................................50 V/Div.
Horizontal Sweep .................2 ms/Div.
Coupling .........................................DC
Trigger .....................................Internal
SCOPE SETTINGS