Lincoln Electric IDEALARC DC-600 Service Manual page 94

F-50
ABNORMAL OPEN CIRCUIT VOLTAGE WAVEFORM
TROUBLESHOOTING AND REPAIR
CONSTANT VOLTAGE INNERSHIELD
ONE OUTPUT SCR NOT FUNCTIONING
20 volts
This is NOT the typical DC output voltage
waveform. One output SCR is not function-
ing. Note the "gap" in the waveform. One
SCR gate is disconnected to simulate an
open or non-functioning output SCR. Each
vertical division represents 20 volts and each
horizontal division represents 2 milliseconds
in time.
Note: Scope probes connected at machine
output terminals: (+) probe to positive termi-
nal, (-) probe to negative terminal.
SCOPE SETTINGS
Volts/Div.....................20V/Div.
Horizontal Sweep .....2 ms/Div.
Coupling.............................DC
Trigger.........................Internal
IDEALARC
CH 1
2ms
® DC-600
F-50
0 volts