Removing Case And Measuring Input Capacitor Voltage In 400 Vac Models - Miller XMT 450 CC/CV Owner's Manual

10-3. Removing Case and Measuring Input Capacitor Voltage In 400 VAC Models

4
Typical Bleeder Resistor
1
2
400 VAC input:
+ lead to lower
terminal, − lead to
upper terminal
.
A complete Parts List is available at www.MillerWelds.com
25 to 1000 ohm,
5 watt resistor
#16 AWG 1000 volts DC
insulation rating, approx.
3 in. (76 mm) leads
3 3
!
Turn Off welding power
source, and disconnect in-
put 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
on unit.
1 Right Side Panel
To remove panel, remove screws
securing panel to unit.
2 Interconnect Board PC2
3 Voltmeter
Measure the DC voltage across the
screw terminals on PC2 as shown
until voltage drops to near 0 (zero)
volts.
.
If the capacitor voltage does
not drop to near zero after sev-
eral minutes, use a bleeder re-
sistor of between 25 and 1000
ohms, at least 5 watts, #16
AWG 1000 volts DC insulating
rating wire to discharge the ca-
pacitor(s) .
4 Typical Bleeder Resistor
An example of a typical bleeder re-
sistor is shown on this page.
Proceed with job inside unit. Rein-
stall right side panel when finished.
277774-A / 256682-B
OM-257220 Page 43