Fault route · No wire feed
NBC / CO2-MIG no wire feed diagnosis
Use this workflow when the torch trigger is pressed but the feeder motor does not drive wire, or the motor tries to run but wire does not move. Start with the visible behavior, then move from mechanical evidence to electrical command evidence.
This page has a specific MIG wire-feed role
This page is the NBC / CO2-MIG system-level no-wire-feed route. It is not the same as a generic MIG fault page or a MIG200DL model-specific page.
Related MIG / NBC wire-feed pages
MIG wire-feed content is separated by scope: broad symptom entry, NBC/CO2-MIG system route, MIG200DL model-specific route, board reference, circuit path and PWM chip reference.
First split: motor silent or motor turning?
Motor is silent
Focus on trigger input, 24V supply, mode switch, relay command, PWM output and motor connector voltage.
Motor turns but wire does not move
Focus on pressure arm, drive roller, liner, contact tip, spool brake, guide tube and wire-feed mechanism.
Evidence order
No-wire-feed fault table
| Observation | Likely area | Next check |
|---|---|---|
| No gas, no relay, no motor | Torch switch, 24V rail or control connector | Check trigger input continuity and 24V to feeder/control board. |
| Gas valve clicks, motor silent | PWM enable, motor driver, motor connector or motor itself | Measure motor output voltage under trigger; check driver transistor/MOSFET and flyback diode. |
| Motor voltage present, motor does not turn | Motor, harness or mechanical jam | Test motor separately with controlled supply and inspect feeder load. |
| Motor turns, wire does not move | Mechanical feed path | Check roller pressure, liner, contact tip, spool brake and drive roller groove. |
| Motor runs only at one speed | Speed-set pot, feedback/control line, PWM IC or LM324 path | Check set-voltage change and PWM duty-cycle response. |
Practical repair rule
Do not diagnose no-wire-feed from the PCB alone. A blocked liner, wrong roller groove, stuck spool brake or broken torch switch can create the same complaint as a bad PWM board. Prove the signal path before replacing ICs.