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Functional signal paths and measurement logic

Welder Circuits

Use Circuits when the technician needs to understand a function path instead of a single board or symptom. Circuit pages explain how gas control, HF arc start, wire-feed output, control power rails, feedback paths, measurement points and inverter board layers connect across models.

Start here by function path

Choose the function you are trying to understand. If you need a step-by-step repair sequence, open Diagnostics after identifying the signal path.

TIG / Plasma

Gas and HF arc-start paths

For torch input, pre-flow, HF command, HV pack, arc transfer, HF cutoff and gas post-flow.

 MIG

Wire-feed and gas-valve control

For trigger input, feeder motor output, gas-valve supply and MIG control-signal split.

 Power rails

Control power rails and measurement points

For named voltages and connectors such as X13, X14, X16, X17, P12, P14 and P17.

 Inverter

Board-stack and power-stage logic

For bottom input/DC bus, top switching/driver and middle transformer/output layers.

How this section relates to Boards and Diagnostics

Circuits explain the function path. Boards explain the physical board or connector. Diagnostics explain what to check step by step for a fault. For example, a TIG no-HF symptom may use a gas/HF circuit page to understand the sequence, then a board page for HF-board evidence, then a diagnostic workflow for the repair order.

Gas, HF and arc-start sequence paths

Use these when the problem involves torch input, gas pre-flow, HF command, arc transfer, HF cutoff or post-flow timing.

TIG HF Arc-Start SequenceTorch input, gas pre-flow, HF command, HV generation, arc transfer and HF cutoff. TIG Gas Solenoid Control PathTorch input, timing logic, output driver, solenoid coil, gas supply and post-flow control. TIG Gas Flows But HF MissingUse after understanding the gas/HF sequence to diagnose no-HF symptoms. TIG HF Stuck OnArc transfer, HF command cutoff, relay/contact and feedback evidence. WSM-315 HF Arc-Start BoardHF relay, HV pack, discharge path and arc-start output hardware. LGK60L HF Arc-Start BoardHF output, plasma arc-start support and gas/start path evidence.

MIG wire-feed and gas-control paths

Use these when trigger, wire-feed motor, gas valve or MIG no-output symptoms need signal-path context.

MIG200DL Wire-Feed / Gas-Valve ControlP13 trigger/jog signal, P14 feeder output and P17 gas-valve supply. MIG200DL Power / Control BoardP12, P6, P13, P14, P17, P11/P16 and drive-output connector evidence. MIG200DL No Wire FeedCurrent potentiometer, P14 DC2-22V and feeder motor route. MIG200DL Trigger But No GasExternal gas, P17 DC24V, gas valve and power-board path. MIG200DL Wire Feeds ContinuouslyStuck P13 input or P14 output route. MIG200DL Trigger But No OutputP12, P11/P16, P1/P2 and output connection split.

Control power rails and measurement points

Use these when the evidence is a connector name, voltage rail, display power, fan/control power or current-feedback point.

Connector and Measurement Point IndexLGK60L X16/X17, LGK100L X13/X7/X14, MIG200DL P12/P6/P13/P14/P17/CON5/CON6. LGK Plasma Cutter Control Power RailsAC rails, DC24V, DC15V/-DC15V and display-power evidence. LGK100L Control Board Connector ReferenceX13 DC5V, X7 rail groups and X14 Hall feedback evidence. LGK60L Main Control BoardX16 DC24V, X17 AC rails and protection/control connector evidence. Hall Current Sensor DiagnosisCurrent feedback evidence used in protection, no-output and weak-current faults. LGK100L Protection LightTemperature relay, rails and Hall-feedback troubleshooting route.

Board-stack and power-stage logic

Use these when the task is to separate input/DC bus, switching/driver, transformer/output, feedback and secondary inverter layers.

Small Inverter Welder Board-Stack MapInput/bottom board, switching/top board, output/middle board and control-panel layer. ZX7-160/200 Board Stack ReferenceBottom board, top inverter board and middle output board service split. Small Inverter Welder Fault IndexDead, relay, fan/no output, protection, MOSFET and output-diode routes. WSE Secondary Inverter BoardAC/DC TIG polarity switching, secondary driver and balance/pulse behavior. WSE AC Output Missing, DC NormalAC/DC command, secondary driver and secondary inverter switching split. Power Device Failure IndexIGBT, MOSFET, rectifier bridge, output diode and repeated failure routes.

NBC wire-feeder PWM and burn-back circuits

NBC wire feeder PWM and burn-back controlTrigger, gas, 2T/4T, speed command, motor PWM and burn-back sequence.

ZX7 / WS feedback and drive circuits

ZX7 / WS feedback, protection and drive pathCurrent command, feedback input, protection logic, PWM enable and driver output route.

WS TIG bottom-board start control circuits

WS TIG bottom-board relay, gas and HF controlHand switch, 24V, relay power, gas valve, HF relay, blocking and post-flow timing.

TIG HF relay and discharge circuits

TIG HF relay, transformer and discharge pathCommand, relay, boost transformer, discharge network, HV diode and coupling path.

WSM-315 gas, HF and feedback circuits

WSM-315 gas, HF and current-feedback pathTorch input, gas solenoid, HF start, current command, inverter drive and HF cutoff.

WSE secondary inverter and driver circuits

WSE secondary inverter and driver signal pathPanel AC command, secondary driver, polarity switching, AC balance, feedback and protection.

NBC wire-feeder PWM and burn-back circuits

NBC wire feeder PWM and burn-back controlTrigger, gas, 2T/4T, speed command, motor PWM and burn-back sequence.

NBC wire-feeder PWM and burn-back circuits

NBC wire feeder PWM and burn-back controlTrigger, gas, 2T/4T, speed command, motor PWM and burn-back sequence.

Circuit paths grouped by fault evidence

Circuit pages connect the symptom route to the board and component-level checks.

NBC wire-feeder PWM and burn-backPWM duty, motor control, burn-back timing and stuck-feed evidence. ZX7 / WS feedback and protectionFalse protection, feedback, thermal input and drive-enable evidence. WS TIG relay, gas and HF controlBottom-board relays, gas solenoid, HF command and timing path. TIG HF relay and discharge pathHF relay, transformer, spark gap, discharge resistor and HV path. WSM-315 gas, HF and feedback pathStart sequence from torch input to HF cutoff and current feedback. WSE secondary inverter signal pathAC command, driver, polarity switching, balance and feedback.