Measure in the order that protects the repair

Repair workflows

Choose the closest symptom or subsystem and follow a controlled sequence: power-off checks, first live measurements, block isolation and staged power-up.

Fast starting points

Open the route that best matches the evidence already available.

No power / no 24 V

Start with input safety, startup VCC and auxiliary rails.

Open workflow →02

No PWM

Check controller supply, reference, timing, shutdown and outputs.

Open this route →03

Before replacing IGBTs

Verify the driver, load path and power-stage resistance first.

Open this route →04

Process sequence

Follow plasma, MIG or TIG command order.

Open this route →

Power-off checks and controlled startup

Reduce the risk of another failure before applying full mains power.

WorkflowInput short and lamp-limiter diagnosisCheck bridge, bus and power devices under controlled current.Circuit pathAuxiliary power supply circuitStartup feed, controller bias, switching stage, transformer, secondary rails and feedback.Checklist toolIGBT replacement precheckRecord resistance, gate and load-path checks before fitting devices.WorkflowZX7-250 staged power-upRestore rails and gate drive in controlled steps.Measurement toolAuxiliary power rail checkerOrganize startup VCC and low-voltage rail readings.

PWM, feedback and gate-drive diagnosis

Move from the controller to the driver and gate without skipping protection signals.

WorkflowControl board shutdown / no PWMSupply, reference, oscillator, protection and output checks.WorkflowPWM feedback and protectionSeparate valid protection from false shutdown.Model workflowZX7-250 complete repair sequencePower stage, rails, PWM, driver and staged startup.Circuit pathZX7-250 gate-drive pathCompare driver primary, transformer secondary and gate branches.

MIG, TIG and plasma process workflows

Follow the command sequence when auxiliary power and the main inverter are already present.

MIG workflowNBC MIG no wire feedTrigger, board supply, motor drive and speed control.TIG workflowTIG HF weak or missingGas, torch command, HF generation and output readiness.Plasma workflowLGK-100 no arcAir, HF, pilot DC, transfer and cutting output.Combination workflowCT-312 protection in all modesSeparate shared power and protection faults from process boards.

Maintenance, tools and case comparison

Use repeatable records and known cases to verify a repair before returning the machine.

Maintenance checklistPreventive maintenanceDaily, monthly and quarterly inspection records.Field workflowEMI and interference routingSeparate mains noise, HF coupling, grounding and signal-path interference.TIG workflowWSE pulse mode not workingCheck panel command, pulse control and secondary-inverter response.Repair casesMeasured repair casesCompare symptoms, readings, fault location and final result.

Next step

Need a component or board reference?

Once the failing block is isolated, open Boards & Chips for pin, rail, connector and driver references.

Boards and chipsOpen board and chip referencesUse the PCB function or device marking.ModelsReturn to the machine familyCheck model-specific board stacks and known differences.CasesCompare with a completed repairLook for matching measurements and the final fault.