Lincoln Electric POWER MIG SVM167-A Service Manual page 61

F-25
TROUBLESHOOTING AND REPAIR
ABNORMAL OUTPUT VOLTAGE WAVEFORM - MACHINE
ONE OUTPUT DIODE NOT FUNCTIONING
MACHINE LOADED TO 180 AMPS AT 16 VDC
This is NOT a typical DC output voltage
waveform. One output diode is not func-
tioning. Note the increased ripple con-
tent. One diode was disconnected to
simulate an open or non-functioning out-
put diode. Each vertical division repre-
sents 20 volts and each horizontal divi-
sion represents 5 milliseconds in time.
The machine was loaded with a resis-
tance grid bank.
NOTE: Scope probes connected at
machine output terminals: (+)
probe to electrode, (-) probe to
work.
LOADED (MAX TAP "G")
20.0 V
POWER MIG® 215
5 ms
SCOPE SETTINGS
Volts/Div.................................20V/Div
Horizontal Sweep.................5 ms/Div
Coupling........................................DC
Trigger....................................Internal
F-25
0 Volts