Repair workflow
TIG Touch-Start Fault Routing: Tungsten Sticking, Failed Arc Start and Unstable Hot Start
A WelderData workflow for diagnosing TIG low-current contact start faults before replacing HF modules or main power devices.
Database summary
TIG touch-start faults are different from conventional high-frequency start faults. The machine may not use an HF spark at all, so the diagnostic path must follow contact detection, short-current limiting, lift-off voltage recognition, hot-start current and final welding-current transfer.
This workflow is intended for machines where the start process uses a small contact current and a controlled current transition. It should be used with the low-current touch-start circuit reference and the TIG auxiliary/protection pages.
Fault routing table
| Observed symptom | Do not assume | Route first to | Measurement evidence |
|---|---|---|---|
| Tungsten sticks during start | Main output must be shorted | Short-current limit and contact-recognition timing | Current during contact, torch motion, work clamp and control-state transition |
| Electrode lifts but no arc forms | HF board is faulty | Arc-voltage recognition and hot-start command | Voltage rise after lift and start-current command evidence |
| Arc flashes then extinguishes | Torch or gas is always the cause | Hot-start duration and transfer to welding-current loop | Current command after start and feedback signal stability |
| Touch start fails but HF start works | Power stage is healthy in all start modes | Contact-start recognition path | Short-state detection and repeat-start logic |
| Start repeats several times then stops | Operator error only | Repeat-start limit, start reset and protection state | Number of attempts, fault latch, voltage-recognition state |
Stop conditions
Stop full-current testing if the tungsten fuses to the workpiece, the output jumps directly to high current during contact, the start current cannot be limited, or the control board does not distinguish short state from arc state. Those symptoms indicate that the start-control loop should be tested before additional output-stage stress is applied.