Repair index
CT-312 Repair Index
A CT-312 combo-machine repair index that routes MMA, TIG and plasma symptoms into board-layer and process-specific pages.
Start here
Use this index when a CT-312 MMA/TIG/plasma combo machine behaves differently by mode, or when gas, HF, plasma air, arc transfer, protection or auxiliary power symptoms overlap.
Mode-first diagnosis
If MMA works but TIG/plasma fails, the shared inverter may be healthy and the fault may sit in mode switch, gas/HF support, torch input or process control. If all modes fail or all modes protect, move to shared inverter/output/protection layers.
Board-layer diagnosis
Bottom board handles auxiliary support, relay/start path, gas/fan/HF sockets. Middle board handles transformer/output diodes/reactor/shunt/feedback/thermal switch. Top board handles switching devices, driver transformer and control module.