Trace transformer and output diode path.
Board reference
CT-312 Middle Board Reference
A middle-board service reference for CT-312 output, feedback and protection diagnosis.
Quick Answer
The CT-312 middle board is the output and feedback layer: main transformer, output rectifiers, reactor, shunt, feedback socket and thermal switch.
- Use it when the machine has OCV/output weakness, protection after start or feedback mismatch.
- TIG/plasma gas/HF faults should be separated before blaming the middle board.
- Thermal switch and shunt evidence are important when protection or weak current occurs.
CT-312 middle-board evidence
| Function | Board-side evidence | Related symptoms |
|---|---|---|
| Main transformer | High-frequency transformer/output conversion path. | No OCV, weak output after driver permission. |
| Output rectifier diodes | Secondary rectification and output path. | No output, weak loaded current, diode short/open. |
| Reactor | Output smoothing/current stability. | Weak or unstable arc under load. |
| Shunt / feedback socket | Current feedback evidence. | Current display mismatch, protection, current not adjustable. |
| Thermal switch | Temperature protection input. | Protection light or shutdown after heat/load. |
Middle-board fault split
Check output evidence only after trigger/control/HF/gas evidence is understood.
Check reactor, output connection and shunt.
Check thermal switch and feedback signal.
Confirm gas/HF/trigger first, then middle-board output path.
Related records
Open these for next steps.