Component-level diagnosis and testing

Welder Components

Use Components when the technician suspects a physical part: IGBT or MOSFET module, rectifier bridge, output diode, Hall current sensor, relay, gas solenoid, capacitor, potentiometer or thermal switch. Component pages should explain how the part fails, what symptoms point to it, what to test before replacement, and which diagnostic workflow or board reference to open next.

Start here by component type

Choose the component group that matches the evidence. If you only know the visible symptom, start from Faults. If you know the board or connector, use Boards first.

Power stage

IGBT, MOSFET and rectifier parts

For breaker trip, repeated device failure, no output, shorted bridge and output-diode faults.

Feedback

Current sensors, shunts and feedback parts

For weak current, false protection, current not adjustable and feedback mismatch faults.

Loads

Gas valves, relays, fans and external loads

For no gas, gas stuck on, relay click/no start, fan failures and output-load control paths.

Protection

Capacitors, potentiometers and thermal switches

For DC bus, current command, thermal shutdown and protection-input evidence.

How this section relates to Diagnostics and Boards

Components explain the part-level test and replacement risk. Diagnostics explain the fault workflow. Boards explain where the component sits in a machine. For example, a shorted IGBT page should link to breaker-trip diagnostics, driver-board evidence and an IGBT replacement precheck tool.

Power devices and rectifier parts

Use these when the fault involves breaker trip, device short, no output, repeated failure, bridge rectifier or secondary output diode evidence.

Welder IGBT Module TestingIGBT short, gate-emitter checks, replacement risk and power-stage evidence. Rectifier Bridge / Diode Module TestingDiode-mode checks for bridge rectifier and breaker-trip diagnosis. Power Device Failure IndexIGBT, MOSFET, rectifier bridge, output diode and repeated failure routes. IGBT / MOSFET Keeps BlowingRoot-cause route before replacing another power device. IGBT Replacement PrecheckPre-power checks before installing and powering replacement devices. ZX7 Output Diode Short / No ArcSecondary rectifier, transformer, reactor, shunt and no-arc output route.

Current feedback, sensors and shunts

Use these when symptoms point to weak current, false protection, current cannot adjust, Hall feedback or shunt feedback mismatch.

Hall Current Sensor DiagnosisCurrent feedback evidence for protection, weak current and no-output faults. LGK100L Weak Cutting CurrentOutput connection, current potentiometer, Hall sensor and shunt evidence. WSM/WSE Current-Control FaultsPanel command, feedback path and output-stage response split. ZX7 Weak Current / Cannot AdjustCurrent command, shunt feedback, reactor and output cable evidence. CT-312 Middle BoardTransformer, output diodes, reactor, shunt, feedback socket and thermal switch. Connector and Measurement Point IndexConnector evidence such as X14 Hall feedback and current-related measurement points.

Relays, gas valves, fans and controlled loads

Use these when a relay clicks but the machine does not start, gas does not flow, gas is stuck on, a fan does not run, or an external load output is missing.

TIG Gas Solenoid Control PathTorch input, timing logic, output driver, solenoid coil and gas supply. TIG Gas Flows But HF MissingGas output works, then HF command and HF hardware must be separated. MIG200DL Trigger But No GasExternal gas, P17 DC24V, gas valve and power-board output route. ZX7 Relay Clicks But No StartRelay coil action, contacts, start resistor, DC bus and auxiliary supply. CT-312 Fan / Auxiliary Power MissingBottom-board supply, relay/start path, fan socket and support evidence. LGK60L Trigger No GasTorch switch, gas socket and solenoid route.

Capacitors, potentiometers and protection parts

Use these when the evidence involves DC bus charging, filter capacitors, current potentiometer command, thermal shutdown or protection inputs.

LGK100L Breaker TripRectifier bridge, filter capacitors, IGBT and driver-board evidence. MIG200DL Breaker TripBridge rectifier, bottom-board capacitors and inverter-board burn evidence. MIG200DL Unstable Welding CurrentCurrent potentiometer, output cable, contact tip and board follow-up. ZX7 Protection Light OnThermal switch, output short, MOSFET short and feedback/protection input. CT-312 Protection in All ModesShared thermal, feedback, output and inverter protection route. MIG200DL Power / Control BoardP12, P6, P13, P14, P17 and related control/power evidence.

TIG HF arc-start components

TIG HF spark gap, discharge resistor and HV diode testingComponent-level checks after the HF command and relay path are proven.

Component-level checks connected to diagnostics

Component pages should be used after the matching diagnostic route has isolated the failed section.

TIG HF spark gap, discharge resistor and HV diode testingUse after gas/HF sequence checks point to the high-frequency start path. TIG HF arc-start diagnosticStart here before replacing HF transformer, spark gap or HV diode parts. WS-250 HF arc-start boardBoard-level context for the HF component checks.