Board reference · WS TIG
WS-200P / WS-200S upper, lower and middle board reference
This page translates the WS-200P and WS-200S board-stack into practical connector and function checks. It is intended for technicians who need to decide which board owns the fault before replacing relays, MOSFETs, SG3525/PWM parts, HF components or rectifiers.
Connector and function reference
| Board / area | Functions to identify | Faults it can create |
|---|---|---|
| Bottom board | Hand switch, relay power, gas valve relay, power relay, AC fan, silicon bridge, HF control and 24V/blocking interface. | No gas, no relay action, no HF command, fan dead, no start sequence. |
| Upper board | Current feedback, current pot, pulse adjustment, thermal switch, protection lamp, auxiliary lamp, DC bus and MOSFET/gate-drive section. | Protection lamp on, current not adjustable, weak output, pulse abnormal, no inverter drive. |
| Middle board | Main transformer plug, current/voltage feedback, shunt, HF control connector, secondary rectifiers and output path. | HF present but no arc transfer, weak output, output diode failure, feedback abnormality. |
| HF board / section | HF relay, boost transformer, discharge resistor, high-voltage silicon parts, HF cable and control input. | No HF, weak HF, continuous HF, gas opens but no start spark. |
What to test before board replacement
Bottom board
Check hand-switch input, 24V/control rail, relay coil voltage and gas-valve connector before replacing relays.
Upper board
Check DC bus, thermal switch, current pot, feedback input and driver output before replacing MOSFETs or control ICs.
Middle board
Check secondary rectifiers, main transformer connection, output path and feedback return before blaming the control board.
Fault-to-board quick map
| Symptom | First board to inspect | Do not forget |
|---|---|---|
| Press torch, nothing happens | Bottom board | Gun switch, 24V, relay power and connector harness. |
| Gas opens, no HF | HF section / bottom-board HF command | HF relay, boost transformer, discharge resistor and high-voltage diode/silicon parts. |
| HF present, no welding current | Upper board and middle board | Drive enable, MOSFET/gate-drive, main transformer and secondary rectifier. |
| Protection lamp on | Upper board | Thermal switch, feedback, power-stage shorts and auxiliary rail. |
| Post-flow too long | Bottom board timing section | Delay capacitor and post-flow conversion path. |
Practical board separation
Bottom board usually owns the “start sequence.” Upper board usually owns inverter drive and protection. Middle board owns output transfer and feedback. HF board owns arc-start energy. Diagnosing by board role prevents random board swapping.
Dedicated WS-180P board reference
For WS-180P-specific board images and future board-layout evidence, use the standalone WS-180P upper board page.