Fault route
CT-312 Protection Light Common to All Modes Diagnostic
A mode-independent CT-312 protection route for faults that appear in MMA, TIG and plasma.
Quick Answer
If protection appears in all CT-312 modes, the first suspect is the shared power/output/protection layer rather than TIG/plasma gas or HF support. Check thermal switch, shunt/feedback, output rectifier and top inverter device evidence.
Diagnostic path
All modes affected → shared output layer → thermal switch → shunt/feedback → output rectifier → top inverter devices.
Evidence table
MMA, TIG and plasma all protected: shared layer likely. Only TIG/plasma protected: mode support path. Protection after heat/load: thermal or output stage. Protection immediately: device short or feedback/protection input.