Fault route
TIG HF Present but Current Drops Out After Start Diagnostic
A TIG route for cases where HF starts the arc but welding current drops out or cannot hold.
Quick Answer
If HF appears and the arc starts briefly but current drops out, the start layer may be working. Check arc-transfer feedback, current feedback, protection input, current command and output-stage response.
Diagnostic path
HF start → brief arc → arc-transfer feedback → current feedback/protection → PWM/current permission → output stage.
Evidence table
HF start occurs: no-HF route is not primary. Current starts then stops: feedback/protection or shutdown path. Current command absent: panel/control path. Driver present but output collapses: power/output path.