Repair workflow
Welding Machine Preventive Maintenance Checklist
A maintenance-to-fault routing workflow for older transformer machines, rectifier welders, inverter welders, TIG/MIG/plasma torches, submerged arc systems and rotary DC arc welders.
Why preventive maintenance belongs in a repair database
Many welding-machine faults are not caused by a failed control IC. Loose output joints, blocked cooling, contaminated contactors, worn torch parts, water-flow problems and dirty boards can make a machine look like it has a power-stage fault. Preventive maintenance records help separate service neglect from board failure.
Maintenance map
Maintenance checklist by system
| System | What to inspect | Faults it can mimic | Record evidence |
|---|---|---|---|
| Input and output terminals | Lugs, screws, cable heat, work clamp, electrode holder, output socket. | Weak arc, unstable current, panel current mismatch, overheating. | Loose/hot joint, cleaned/replaced part, load result. |
| Cooling path | Fan direction, dust, blocked heat sink, water flow, pump, radiator and hoses. | Thermal protection, short weld then stop, repeated IGBT/SCR stress. | Flow/air evidence, temperature after service. |
| Contactor and relay contacts | Coil resistance, contact surface, pull-in action, chatter, burnt terminals. | No output, intermittent output, fuse blows, unstable arc. | Coil reading, contact condition, voltage at coil. |
| Control connectors and harness | Loose plugs, water ingress, torch switch lines, remote box, feeder cable, CN connectors. | No gas, no feed, no PWM, false protection, random stop. | Connector number, continuity, cleaned/secured action. |
| Torch and consumables | MIG tip/liner/drive roll, TIG tungsten/torch switch, plasma nozzle/electrode/swirl ring. | Poor arc start, porosity, wire burn-back, plasma no transfer, cut bevel. | Part condition and change after replacement. |
| Transformer / reactor / motor | Noise, vibration, heating, insulation, brush/commutator on rotary machines. | Weak output, overheating, unstable output, motor runs but no output. | Temperature, insulation result, brush/contact evidence. |
| Board cleanliness | Dust, metal powder, carbon tracking, moisture, cracked solder joints. | False shutdown, no PWM, leakage, weak control signal. | Before/after cleaning, suspect area, validation result. |
Maintenance-to-diagnostic routing
| Observed condition | Start here | Next diagnostic path |
|---|---|---|
| Machine overheats quickly | Fan, heat sink, duty cycle, hot output terminals. | AC transformer overheating or inverter thermal protection workflows. |
| Arc is weak after repair | Output cable, work clamp, current feedback, secondary rectifier, drive setting. | ZX7 series fault table or rectifier workflow. |
| MIG wire feed is unstable | Liner, tip, drive roll, feeder cable, torch trigger, motor path. | MIG/MAG common fault routing. |
| TIG or plasma starts poorly | Torch consumables, gas/air pressure, HF gap, work return. | TIG diagnostics or KLG-60 plasma routing. |
| Protection trips after a short weld | Cooling, thermal switch, current feedback, cable short, output diode/SCR heat. | IGBT/MOSFET keeps blowing or SCR/rectifier workflows. |