Kemppi Fastmig M Series Parts FAQs
Spares for a modular MIG welder and its wire feeder and water cooler, and how to match and fit them safely.
Is it safe to open a MIG power source to fit a circuit card or capacitor card?
Only a competent person should do it. Welding power sources contain mains voltage and, in inverter designs, capacitors that can hold a charge after the machine is switched off. Switch off, disconnect the mains supply and follow the maker's service instructions for waiting and discharging before touching any internal part.
Use a qualified electrician for electrical repairs and testing, and never use damaged or faulty equipment. The HSE has also reported a fatal shock where welding equipment was not switched off. The wait time and discharge method depend on the machine, so check the service manual.
What wears out in the wire feeder, and what should I check before replacing electronics?
Mechanical parts wear far more often than electronics. Worn, wrong-size or badly tensioned drive rolls, a worn or kinked liner and a worn contact tip are frequent causes of erratic feeding, and welding consumable makers advise checking the rolls and tip before the liner, which is more work to replace.
If the rolls do not turn at all when the trigger is pulled, look for a fault in the connections, trigger or control leads. Too much roll tension can deform the wire and damage the liner and tip. Only after the mechanical side is ruled out is a feeder card or motor likely to be the cause.
Why are flat cables and connectors worth replacing when damaged?
Internal cables and connectors carry control signals and power between cards, so a damaged one can cause intermittent faults that are hard to trace. Look for cracked insulation, bent or burnt pins, loose plugs and signs of overheating.
Keep machine terminals and lead connections clean and tight, and never use damaged or faulty equipment. Fit a replacement of the same type and length as the original, seat the connector fully and route the cable away from sharp edges and heat. Disconnect the mains and follow the maker's instructions before opening the unit.
What do I need to know about water cooler parts and coolant?
A water cooler circulates coolant through the torch and hoses, so its pump, tank, filter and hoses all need to be sound. Use the coolant type the maker specifies and change it on the maker's schedule. Many makers advise against plain tap water because minerals can scale up and restrict flow, but check your manual.
Check regularly for leaks. A trade guide to welding equipment says leaks at the torch need immediate attention because of the risk of electric shock. Switch off and isolate the machine before working on the cooler, and use a competent person for pump or electrical repairs.