Circuits

Circuit Function Index

Circuit-function index for auxiliary supplies, dual-voltage input systems, PWM shutdown paths, wire-feed control and HF start.

Records

Auxiliary power supply — 24V, 15V, 12V and 5V rails generated by KA3843/KA3845 style auxiliary supplies.
Dual-voltage 220V / 380V input systems — Voltage detection, boost/doubler switching, relay control, comparator logic and wrong-voltage patterns.
Control board shutdown and no-PWM path — Protection, VRD, current feedback, optocouplers and transistor stages that block PWM output.
MIG wire-feed speed control — Trigger input, 2T/4T logic, motor control, gas valve, braking and speed regulation.
TIG and plasma high-frequency start circuit — HF transformer, spark gap, high-voltage capacitor, trigger path, pilot arc and arc-transfer feedback.
Full-bridge MOSFET inverter power stage — DC bus, switch groups, blocking capacitors, transformer drive and secondary rectifier flow.
ZX7-250 control power rails — ±25V, 7815, 7805 and 7915 regulation chain.
ZX7-250 driver transformer and gate drive — N/P pair, four outputs, gate resistors and fast diode checks.
ZX7-250 overcurrent and thermal protection — current transformer feedback and 85C switch.
ZX7-250 current shunt and real output current — simulated display vs 75mV shunt measurement.
ZX7-250 220V/380V relay boost and DC bus — dual bridge, relay logic and 530-560V bus.
ZX7-250 output choke and arc stability — fast diodes, snubbers and output reactor.
ZX7-250 24V relay and 510V DC bus enable — Relay-enabled high-voltage bus path from power board to upper board.

Circuit pages explain functional signal flow and connect faults to boards and chips.