1Bottom board
DC bus capacitors, 24 V socket, main relay, start resistor, gas / fan / HF sockets.
Board-stack reference
CT-312 Board Stack Reference
A practical CT-312 board-stack map for separating power, gas, HF, feedback and mode-switch faults.
Board-stack role
The CT-312 board stack should be read by function, not just by physical board position. The bottom board carries control power, relay and auxiliary-load connections; the middle board ties transformer/output/reactor/feedback evidence; the top board handles inverter and driver-related power behavior.
Board-stack reference
CT-312 board stack map
Function-based board routing for CT-312 MMA / TIG / plasma combo machines.
2Middle board
Main transformer, rectifier diodes, reactor, shunt, thermal switch and feedback socket.
3Top inverter board
Power devices, driver transformer, control module and board supply.
TIG mode
Torch switch, HF start and gas solenoid path.
Plasma mode
Cutting arc, air/gas path and pilot-arc behavior.
MMA mode
Main output, arc force and thermal protection.
Repair split
Separate board stack, mode switch, gas / HF control and real output evidence.
Board evidence table
| Board / area | Typical signals or parts | Fault clues |
|---|---|---|
| Bottom board | DC bus, 24 V, main relay, start resistor, gas/fan/HF connectors | fan/gas/HF/control-power faults. |
| Middle board | main transformer, reactor, shunt, rectifier diodes, thermal switch | weak output, feedback/protection, no OCV. |
| Top inverter board | power devices, driver transformer, control module, supply indicator | breaker trip, no switching, IGBT/MOS fault. |
| Mode switch area | MMA/TIG/plasma selection path | one mode works while another mode is dead. |