Fault route
CT-312 HF Present but No Arc Transfer Diagnostic
A CT-312 route for TIG/plasma cases where high frequency appears but the main arc does not transfer.
Quick Answer
HF presence means the start-support path is at least partly working. If the arc still does not transfer, check torch consumables, work return, output cable, middle-board transformer/output diodes and feedback path.
Diagnostic path
HF present → torch/work return → output terminal path → middle-board transformer/rectifier → shunt/feedback.
Evidence table
HF present with no arc: not a pure HF-board fault. Bad work return or torch consumables can block transfer. Middle-board output diode/transformer/reaction path can also prevent main arc.