Board reference · WSE AC/DC TIG
WSE secondary inverter board reference
Use this page when a WSE AC/DC TIG welder has DC output but no AC welding output, AC waveform only in one direction, unstable AC balance, no cleaning action, or secondary inverter drive faults. The secondary inverter board should be diagnosed as the AC polarity-switching stage, not as the same board as the main DC inverter.
Secondary inverter role map
In many WSE AC/DC TIG machines the main inverter creates controlled welding power, while the secondary inverter stage reverses or shapes output polarity for AC TIG. A machine can weld in DC while the AC secondary stage is still faulty.
Board-area fault map
| Area | What it controls | Fault symptom |
|---|---|---|
| AC/DC command | Selection signal from panel/control board. | DC works but AC mode behaves like DC or no AC output appears. |
| Secondary driver input | Receives timing and polarity commands. | No alternating gate command, one-sided waveform, protection in AC mode. |
| Secondary power devices | Switch output polarity under driver control. | Shorted devices, blown fuses, breaker trip, output only one polarity. |
| Balance/frequency command | Adjusts AC cleaning/penetration behavior. | Balance knob has no effect or AC arc feels fixed/unstable. |
| Feedback/cutoff | Reports abnormal output or current state. | False protection, AC starts then stops, weak or unstable AC output. |
Do not diagnose WSE AC faults as ordinary DC no-output faults
If DC mode welds normally but AC TIG fails, the first suspect is not the main inverter. Check AC/DC command, secondary driver, secondary power devices, balance/frequency command and output feedback.