Section 9 − Troubleshooting; Removing Cover And Measuring Input Capacitor Voltage - Miller Axcess 300 Owner's Manual

SECTION 9 − TROUBLESHOOTING

9-1. Removing Cover and Measuring Input Capacitor Voltage

Tools Needed:
5/16 in.
3
Typical Bleeder Resistor
25 to 1000 ohm, 5
watt resistor
#16 AWG 1000 volts
DC insulation rating,
approx 3 in. (76 mm)
leads
1
+ lead to left bus terminal, − lead to right bus terminal
!
Turn Off welding power
source,
input power.
!
Significant DC voltage can
remain on capacitors after
unit is Off. Always check the
voltage as shown to be sure
the input capacitors have
discharged before working
2
on unit.
Turn Off welding power source, and
disconnect input power.
Remove cover
1 Interconnect Board PC2
2 Voltmeter
Measure the DC voltage across the
+ bus terminal and − bus terminal on
PC2 as shown until voltage drops to
near 0 (zero) volts. Measure input
capacitor voltage
assembly before proceeding.
.
If the capacitor voltage does
not drop to near zero after
several minutes, use a bleeder
resistor of between 25 and
1000 ohms, at least 5 watts,
#16 AWG 1000 volts DC
insulating rating wire
discharge the capacitor(s).
3 Typical Bleeder Resistor
An example of a typical bleeder
resistor is shown on this page.
Proceed with job inside unit.
Reinstall cover when finished.
and disconnect
on inverter
to
802 985 / Ref. 803 670-A
OM-216 967 Page 33