Kemppi Minarc 300 TIG

  1. Dennis Aspö

    Dennis Aspö Member

    Messages:
    936
    Location:
    Finland
    Been inquiring about this machine (page in finnish)
    http://www.nettikone.com/kemppi/minarc-300-tig/1527467

    The seller finally responded, turns out it's a company called Hemax welding and it's their old machines they're selling off so who knows if they're worn out or not if they have been in professional use. The price 500€ is excluding vat. They'll test the machine that it works before sending it out they say.

    Seems like a pretty beefy machine, with HF start and slope functions, MMA welding up to 270A and TIG 280A. 100% duty cycle up to 150A. I doubt for my purposes I'll cross 150A... Good thing about the design is that it has air filters so the insides should be better protected than most shop machines.

    I dunno really, 500 was OK I might chance an older machine... Still, seems welders are more expensive here in Finland.

    I got a pretty good offer for a new minarc 200 EVO TIG from rapidwelding.co.uk with CK17 torch retrofitted & free shipping for roughly 1280€+vat.
     
  2. Dennis Aspö

    Dennis Aspö Member

    Messages:
    936
    Location:
    Finland
    Got some pics
    [​IMG]

    [​IMG]

    [​IMG]
     
  3. Dennis Aspö

    Dennis Aspö Member

    Messages:
    936
    Location:
    Finland
    Well I bought one of the above welders.
     
  4. Dennis Aspö

    Dennis Aspö Member

    Messages:
    936
    Location:
    Finland
    It seems to weld fine, has an annoying sound in stick mode but apparently that's the sound it's supposed to make when in standby. LCD display for amperage is faded however and I can't really make out what amps it's at, that's pretty annoying. Think I need to take it to a service station and see if they can swap out the display and give it a general once over.
     
  5. zeppelin builder

    zeppelin builder Member

    Messages:
    1,163
    Location:
    peoples republic of scotland
    hi Dennis your in the home of kemppi so parts and service should be easy .i like the old kemppi stuff real good quality developed from the old powcon technology
    ps worked in Autokumpo at Vantaa many years ago
     
  6. Dennis Aspö

    Dennis Aspö Member

    Messages:
    936
    Location:
    Finland
    There's a kemppi service center near me, but they have crappy opening hours, the distance from my work means it's literally impossible to make it with the welder there before they close. I'm looking at the panel and circuit board now and it's basically the only dirty part in the machine. I will clean the board and see if that helps, might just be a case of dirt and bad connections.
     
  7. Dennis Aspö

    Dennis Aspö Member

    Messages:
    936
    Location:
    Finland
    Some images of the insides

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    All in all the insides look very clean and in nice shape, except the one board with the display which is dirty. I think a lot of dirt must get in right there...
     
  8. Dennis Aspö

    Dennis Aspö Member

    Messages:
    936
    Location:
    Finland
    Ressurecting this old thread. I replaced the display and that's been working fine since then. I took it apart again today for some service and checkup. I looked at the components, blew it out with compressed air. Not a lot of dust in it despite the very dusty environment. I figure that's because the fan only turns on when it gets warm enough and that's happened like three times total in two years. That's a definite pro of a 300A welder when you usually keep under 150A (100% duty cycle up to 180A), so it never gets to suck in much dust, and also has a filter.
    [​IMG]

    Giving the electrolytic capacitors an extra careful inspection. I don't know much about electronics except that they are prone to failure with age and this thing is from 1994. But they look real good.
    [​IMG]
    [​IMG]

    All cleaned up. That's a very temporary welding cart. Should put something nonflammable over the wooden stuff. Want to build a compact one soon.
    [​IMG]

    Someone pointed out though that those square yellowish capacitors are likely Rifa capacitors and are failure prone, especially if the epoxy gets cracks in them. I zoomed in and yeah:
    [​IMG]

    Maybe I should get to replacing all those types of capacitors with new ones? I wonder if this has any effect on the welders performance as they degrade or if the capacitor will just explode once it gives up? I have thought my TIG arc behaves badly at low amps. Perhaps there's a connection?
     
  9. Richard.

    Richard. Member

    Messages:
    18,093
    Location:
    Cambridgeshire
    Hi Dennis
    Just seen your thread and it’s an interesting write up.
    Good Welders from the 90’s seem to be Very well built and quite common to see them still in full time production. My Fronius magicwave is a 1993 model and like wise the design internally tends to keep the crap off the boards. Mine looks rather clean externally too which probably shows it’s not really seen a hard life mind.
    What I would do if I was you is keep a good eye out for a scrapper so you’ve got lots of spares because those machines are obsolete as are a lot of the boards, spares.
     
  10. Dennis Aspö

    Dennis Aspö Member

    Messages:
    936
    Location:
    Finland
    Well it seems most of what can go wrong on this machine are electronic components failing and they're as far as I can see standard components that can be purchased in stores and I got a circuit diagram for this machine too (huge image).

    Which reduces my dependancy on stuff like search for spare boards, which would most likely suffer the same issues as what caused the ones I got to fail, i.e. age related failure. So to me, component replacement is the best way to go. Fortunately the circuit boards are built big enough that they can be hand soldered. With a modern inverter I don't think that would have been on the table.
     
  11. Dennis Aspö

    Dennis Aspö Member

    Messages:
    936
    Location:
    Finland
    I've bought spare components and an ESD mat to be on the safe side. I could not find any capacitors* with the right leg spacing so I bought more of the same kind, the metallized paper foil kind, but I understand the new ones are more reliable since they changed the epoxy in the late 90s and still, the old ones with the bad rep lasted a good while anyhow.

    * I have to stop myself every time from writing condenser which is the old timey word, we call them kondensator in swedish and kondensaattori in finnish.

    BTW I was wondering if a welding table isn't a very good ESD surface (albeit a hard surface), if it's hooked up to the welding ground clamp shouldn't the whole table be grounded via the electrical socket then?
     
Advertisements