Troubleshooting - Miller Electric CST 250 Owner's Manual

5-3. Troubleshooting

Trouble
No weld output; unit completely
inoperative.
No weld output.
Blue LED flashes continuously, yellow Blue LED flashes continuously yellow
LED off.
No weld output.
Blue LED flashes 4 times repeatedly,
yellow LED off.
No weld output.
Blue LED flashes 5 times repeatedly,
yellow LED off.
Low weld output.
Blue LED flashes 2 times repeatedly,
yellow LED off. yellow LED off.
No weld output.
Blue LED flashes 3 times repeatedly,
yellow LED off.
No weld output.
Blue LED flashes 6 times repeatedly,
yellow LED off.
No weld output.
Blue LED off, yellow LED on.
No weld output.
Blue LED off, yellow LED flashes
continuously.
Fan not operating.
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Possible Causes
Line disconnect switch open.
Blown line fuse(s).
Improper input power connections.
Line voltage too high or too low.
Unit not linked correctly.
Unit needs to be reset.
Voltage in excess of 100 V from an
external source across output studs.
Short circuit across output studs.
Single phase rating exceeded (output
foldback due to excessive input current).
High output VA coupled with a low 230
voltage line (output foldback due to
excessive input current).
Remote trigger left on.
Internal component failure.
Unit overheated.
Thermistor failure.
Blocked fan blade.
Fan failure.
1 Output LED (Blue)
2 High Temperature LED
(Yellow)
Remedy
Place line disconnect switch in On position (see Section
3-12).
Check and replace line fuse(s), if necessary, or reset
circuit breaker (see Section 3-12).
Check for proper input power connections (see Section
3-12).
Line voltage must be within 10%.
Check line voltage and link unit accordingly.
Cycle power switch off and back on again. If problem is not
corrected, contact nearest Factory Authorized Service
Agent.
Check and correct any external voltage sources.
Check and correct any short circuit conditions.
Reduce output to 200 amperes or less.
Check line voltage and weld settings.
Turn off remote trigger, wait approximately 5 seconds, and
restart operation.
Contact nearest Factory Authorized Service Agent.
Allow unit to cool.
Have Factory Authorized Service Agent check thermistor.
Check and remove anything blocking fan blade movement.
Have Factory Authorized Service Agent check fan motor.
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