Miller Big Blue 450 Duo CST, Owner'S Manual

Page: 46 / 64

Complete Parts List is available at www.MillerWelds.com
OM-266621 Page 42
8-12. Troubleshooting CST
1 Output LED (Blue)
2 High Temperature LED
(Yellow)
803 942-A
1
2
Repeated LED Flashes
Indicate Status
Blue Yellow Trouble Possible Causes Remedy
None None
No weld output;
unit completely in-
operative.
Blown fuses.
Check and replace line fuses, if neces-
sary (see Section 8-11).
Alternating
Blue And
Yellow
Alternating
Blue And
Yellow
Process Select switch is between positions.
Verify Process Select switch is not
between positions.
Flashes
Continuously
0 No weld output. Not ready. Buss voltage imbalance.
Have Factory Authorized Service Agent
check DC bus caps and PC2, and re-
place if necessary.
6 0 No weld output.
Over current
fault.
No primary line feedback.
Have Factory Authorized Service Agent
check CT1 and wiring for an open con-
dition.
Failed output diode(s).
Have Factory Authorized Service Agent
check diodes for shorts or opens in wir-
ing.
Failed boost inductor.
Have Factory Authorized Service Agent
replace boost inductor if necessary.
Failed LEM.
Have Factory Authorized Service Agent
replace LEM if necessary.
Open connection between
LEM and PC13.
Have Factory Authorized Service Agent
inspect internal wiring and connections.
Failed PC13.
Have Factory Authorized Service Agent
replace PC13.
4 0 No weld output.
Over voltage
fault.
Shorted boost relay.
Have Factory Authorized Service Agent
check for a shorted relay or wiring.
Boost relay does not
deenergize after termination
of weld.
Have Factory Authorized Service Agent
check PC13.
Voltage in excess of 100V
from another source applied
across output studs.
Check for external voltage sources.
5 0 No weld output. Voltage loss.
Voltage feedback leads not
connected or reversed.
Have Factory Authorized Service Agent
check voltage feedback leads for prop-
er wiring and connection.
Short circuit across output
studs.
Check for shorts.
Failed IGBT on PC2.
Have Factory Authorized Service Agent
check PC2 and replace if necessary.
Failed PC13.
Have Factory Authorized Service Agent
replace PC13.