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Plasma diagnosis

LGK-100 Plasma Cutter No Arc Routing

When an LGK-100 has air but no arc, or arc start is weak, separate the fault into air supply, panel mode, torch switch, consumables, pilot arc path and main cutting current.

Start at the front panel: air check/cutting mode, 2T/4T selection, protection lamp and current knob.
Start at the front panel: air check/cutting mode, 2T/4T selection, protection lamp and current knob.
Then check the external path: input power, compressor, work clamp and torch cable/gas hose.
Then check the external path: input power, compressor, work clamp and torch cable/gas hose.
Finally inspect torch consumables: wrong order, worn electrode/nozzle or poor coaxial assembly can prevent reliable arc transfer.
Finally inspect torch consumables: wrong order, worn electrode/nozzle or poor coaxial assembly can prevent reliable arc transfer.

No-arc routing table

SymptomCheck firstRepair direction
Fan runs, no arcPanel mode, protection lamp, work clamp and torch switch.Confirm cutting mode and control connection before board replacement.
Air flows, no pilot arcTorch consumables, HF/pilot section and torch cable.Replace worn consumables; then inspect pilot-arc circuit.
Pilot arc exists but no cutting currentWork clamp, transfer arc lead and main output path.Check output cable and rectifier/output section.
Poor cutting or weak arcAir pressure, moisture, nozzle/electrode condition and travel speed.Correct air system and consumables before blaming the control board.