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Aluminium tig problems

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  • #16
    OP. Judging from everything you've stated and the picture you've provided I agree that the main switch isn't
    1. entirely locked into AC
    or
    2. the contacts need to be cleaned if it has been set to DC for several years

    Good luck sir

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    • #17
      It sounds like it is not switching over to me. It is melting the material but not cleaning it at all. I will get a piece of aluminium from school put a bead on it with the tig machine there I know works properly then being the same piece home and try it on my machine to rule out the material variable. How do I take the machine apart and clean the contacts to try and get ac back if that’s the issue? When I am trying to use it I’m not really paying attention to the sound bike I will next time I go out to the shop.

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      • #18
        Originally posted by 72challengerman View Post
        It sounds like it is not switching over to me. It is melting the material but not cleaning it at all. I will get a piece of aluminium from school put a bead on it with the tig machine there I know works properly then being the same piece home and try it on my machine to rule out the material variable. How do I take the machine apart and clean the contacts to try and get ac back if that’s the issue? When I am trying to use it I’m not really paying attention to the sound bike I will next time I go out to the shop.
        The way the selector lever works the contact points can't be touching both AC and DC positions at the same time. If you're getting an arc and enough power to melt the material you're getting current passing through the contact points. It won't hurt to clean them, but they make pretty robust contact, and the way they're shaped they tend to scrape off any corrosion that would be there from sitting over time.

        Remove the side covers and top cover completely. Then look at the left side of the machine, right as you look at it, and you'll see the brass colored tube that connects to the selector handle. That runs back to a set of brass colored contact fingers that are like blades set in a T shape with each group 90* from the other group.

        I didn't take this picture with this in mind...look for the blue canister at the top (silver on some machines) and just below and inboard of that you'll find the contact points. I simply hit them with compressed air, sometimes a dry paint brush, then wipe them with dielectric grease and have never had to do anything else. Click image for larger version

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        • #19
          Ok. If I clean them and the problem persists, what else could it be? I would like to fix it myself rather than take it to a place that services equipment.

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          • #20
            Ok I’m out in the garage and have got some more info. When I put it to electrode positive it cleans the metal but doesn’t melt it really and balls up the tungsten. When I turn it to ac it doesn’t ball the tungsten but makes a buzzing noise. When I turn it to electrode negative aside from the noise it makes the exact same weld as when I put it in ac mode, no visible puddle. When I am not flooring it on ac mode it flickers on and off. When I give it lots of power it seems to stabilise but still isn’t perfect. So no cleaning action in ac mode and an arc that isn’t really stable and requires lots of amperage to keep it from flickering on and off. I’m totally stumped. I doubt it’s getting very much of the electrode positive cycle if any at all. It is set to continuous high frequency. Any help is appreciated.

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            • #21
              If you have a multimeter, you could check a couple things.
              What is the "open circuit voltage"? This is checked with the HF switch in OFF. Put your leads across the output studs and step on the pedal.
              That machine should have digital meters. Make sure the voltage on the multimeter matches the machines digital meter. I think it should be around 60 volts AC. I'd have to look up the voltages specs to be exact but if there is a problem with one of the SCRs, it will be very low. Like only 30V.
              You really need an oscilloscope to troubleshoot this properly. It will tell you if the AC is correct and the SCRs are firing properly.
              It still sounds like bad gas to me.
              Have you tried a known good bottle of 100% ARGON? It doesn't take much contamination in the bottle to create this problem you are seeing.
              The other thing that causes this is a contaminated torch or torch parts.
              I can't tell you how many times I've cured this problem with new collet, collet body and cups.

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