Fault route
CT-312 TIG Arc Starts Then Stops Diagnostic
A CT-312 TIG route for faults where arc start begins but welding current cannot hold.
Quick Answer
If TIG starts briefly then stops, the trigger/gas/HF support layer may be working. Move to arc-transfer feedback, current feedback, thermal/protection input, middle-board shunt path and top-board drive permission.
Diagnostic path
Torch/gas/HF OK → arc starts → transfer feedback → current command → shunt/feedback → protection input → output drive.
Evidence table
HF and gas OK but current drops: feedback/protection path. Current command missing after start: control/mode path. Current collapses under load: middle-board output or top-board drive/load issue.