Lincoln Electric SVM120-A service manual Abnormal Open Circuit DC Weld Voltage Waveform

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F-43 F-43

TROUBLESHOOTING & REPAIR

ABNORMAL OPEN CIRCUIT DC WELD VOLTAGE WAVEFORM

HIGH IDLE - NO LOAD - OUTPUT CONTROL AT MAXIMUM

ONE OUTPUT DIODE NOT FUNCTIONING

CH1

0 volts

50 volts 5 ms

This is NOT the typical DC (+) output voltage waveform. One output diode is not functioning. Note the “gap” in the waveform. One output diode was disconnected to simulate an open or non-functioning output diode. Each vertical division represents 50 volts and each horizontal division repre- sents 5 milliseconds in time.

Note: Scope probes connected at machine output terminals.

SCOPE SETTINGS

Volts/Div	50V/Div.
Horizontal Sweep	5 ms/Div.
Coupling	DC
Trigger	Internal

RANGER 10-LX