Miller XMT 450 CC, Техническое руководство, Страница: 42 / 84

PRE-POWER CHECKS
TM-257 220 Page 38 XMT 450 CC/CV
10-2. Removing Case and Measuring Input Capacitor Voltage
!
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 Outside Handle Screws
To loosen top, remove two outside
handle screws from both handles
and all side screws.
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.
Ref. 256 682-A
2
3
400 VAC input:
+ lead to lower
terminal, − lead to
upper terminal
Typical Bleeder Resistor
25 to 1000 ohm,
5 watt resistor
#16 AWG 1000 volts DC
insulation rating, approx.
3 in. (76 mm) leads
3
4
1
1