Miller XMT 450 CC, Technical Manual, Page: 51 / 84

Always check unit before applying power (see Section 10-1).
TM-257 220 Page 47 XMT 450 CC/CV
Display
Code
Fault Description Probable Cause(s) Potential Solution(s)
Help 6
Or
−−−−−−−
Primary Bus Ca-
pacitor Voltage Im-
balance.
LED2 is lit on In-
verter Control
Board PC1.
Voltage difference between
bus capacitors exceeded
100 volts. Bus discharge resistors de-
fective on interconnect PC 2. Check resistors.
(see Section 10-5)
Defective input capacitors. Replace C3, C4, C5, and C6.
R1, R6, R12, R13 Check resistors.
(see Section 10-5)
Gate lead wiring is incorrect. Check gate lead wiring and
repair or replace as needed.
Inverter Control board PC1
malfunction. Replace PC1.
DI/DT inductors L3 and L4
malfunction. Check DI/DT inductors L3
and L4. Replace L3 and L4 if
necessary.
IGBTs PM1 and PM2 are not
closely matched. Replace PM1 and PM2.
Help 25 Over Duty Cycle Exceeded output duty cycle
limit. Output stops and cooling
fan runs. Operator was welding at too
high of a welding current for
too long. With unit on, wait 15 minutes
for unit to cool. Reduce am-
perage, voltage, wire feed
speed, or duty cycle before
welding.