Troubleshooting & repair – Lincoln Electric IDEALARC SVM 122-A User Manual
Page 83
TROUBLESHOOTING & REPAIR
F-39
F-39
LINCOLN
®
ELECTRIC
IDEALARC DC-400
This is NOT the typical DC output
voltage waveform. One output SCR
is not functioning. Note the “gap” in
the waveform. One SCR gate is dis-
connected to simulate an open or
non-functioning output SCR. Each
vertical division represents 20 volts
and each horizontal division repre-
sents 5 milliseconds in time.
Note: Scope probes connected at
machine output terminals: (+) probe
to positive terminal, (-) probe to neg-
ative terminal.
SCOPE SETTINGS
Volts/Div.....................20V/Div.
Horizontal Sweep.....5 ms/Div.
Coupling ............................DC
Trigger .........................Internal
ABNORMAL OPEN CIRCUIT VOLTAGE WAVEFORM
CONSTANT VOLTAGE SUBARC
ONE OUTPUT SCR NOT FUNCTIONING
CH1
0 volts
5 ms
20 volts