Abnormal Open Circuit Voltage Output Capacitor Bank Not Functioning - Lincoln Electric POWER MIG SVM170-A Service Manual

F-34
ABNORMAL OPEN CIRCUIT VOLTAGE
OUTPUT CAPACITOR BANK NOT FUNCTIONING
20.0 V
This is NOT the typical DC output voltage
waveform. The output capacitors are not
functioning. Note the lack of "filtering" in the
output waveform. The output capacitor bank
was disconnected.
represents 20 volts and each horizontal divi-
sion represents 5 milliseconds in time.
NOTE: Scope probes connected at machine
output terminals: (+) probe to electrode, (-)
probe to work.
TROUBLESHOOTING AND REPAIR
Each vertical division
POWER MIG 255C
5 ms
SCOPE SETTINGS
Volts/Div . . . . . . . . . . . . . . . . . . 20 V/Div
Horizontal Sweep . . . . . . . . . . 5 ms/Div
Coupling . . . . . . . . . . . . . . . . . . . . . . DC
Trigger . . . . . . . . . . . . . . . . . . . . Internal
F-34
0 VOLTS