Repair Case
TIG No High-Frequency Start
Use this page when a TIG welder has welding output or gas response but the high-frequency arc-start circuit does not fire.
Checks by symptom
| Condition | Likely section | Check |
|---|---|---|
| No gas, no HF | Torch trigger or control logic | Trigger connector, 2T/4T logic, control supply |
| Gas works, no HF | HF board enable or HF board supply | HF relay/driver and board voltage |
| Weak ticking only | Spark gap or HV transformer | Gap spacing, carbon tracking, transformer output |
| HF exists but arc does not start | Torch, ground, coupling path | Tungsten, clamp, cable and coupling capacitor |
Common faults
- Dirty or misadjusted spark gap.
- Failed HF relay or driver transistor.
- Cracked coupling capacitor.
- Carbon tracking on the HF board.
- Broken torch switch or ground clamp issue.