Circuit reference
Output Reactor and Arc Current Stability
Diagnose weak loaded current, unstable arc and CO2/MIG spatter by proving the output rectifier, reactor, shunt and real current path.
Database summary
The output reactor is not only a design component. In MMA, TIG and CO2/MIG welders it shapes current rise, current decay, arc recovery and welding feel. A machine may show normal OCV but still have weak, harsh or unstable loaded current.
Symptoms that should include the reactor
| Observed fault | Reactor / output path possibility | Evidence to collect |
|---|---|---|
| OCV normal but welding force weak | Output path cannot support loaded current. | Loaded current, diode-module heat/drop, reactor continuity and shunt evidence. |
| CO2 / MIG spatter excessive | Current rise or decay is wrong during short-circuit transfer. | Voltage/current waveform, reactor connection and magnetic core condition. |
| Arc harsh after power-board repair | Wrong reactor path, loose busbar or altered return path changed dynamics. | Wiring comparison, terminal tightness, heat and output path resistance. |
| Current feedback unstable | Reactor ripple or pickup path contaminates shunt/CT signal. | Compare feedback with real output current and inspect grounding/routing. |
Repair checks
- Inspect discoloration, loose terminals, cracked core, overheated winding and mechanical vibration.
- Check busbar, output terminal, shunt, work-return and torch/work cable joints.
- Compare continuity and low resistance with a known-good unit when possible.
- Use loaded current evidence rather than open-circuit voltage alone.
- In CO2/MIG, record voltage collapse, current rise, short clearing and re-ignition stability.
Diagnostic path
| Symptom | Weak loaded current, harsh arc, unstable MIG transfer, spatter or current feedback noise. |
|---|---|
| Evidence | Loaded current, output path resistance, reactor heat/continuity and voltage-current waveform. |
| Circuit section | Output rectifier, output reactor, shunt/CT, output terminals and cable return. |
| Next pages | CO2/MIG waveform diagnosis · Powers on but no output · Current display vs shunt check |