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330A/BP, another no HF post

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  • 330A/BP, another no HF post

    I recently picked up an old 330A/BP for my home shop. Tonight was the first time i tried firing it up. I found that the HF isn't reaching my torch. I've seen plenty of threads about No HF on these but mostly focus on the caps or contacts. The machine was pulled out of service and replaced with a new one for unknown reasons.

    My contacts measure .008" gap and when I hit the pedal I have a good blue spark between both of them. The caps aren't original so I assume someone was chasing this same issue.

    The settings I attempted are:

    Amp Control: Remote
    Contact Control: Remote
    Output: AC
    HF: Continuous
    HF Knob: 100%
    Large Lever: TIG
    Amperage: Middle Setting - 70%

    anything I'm reading says I must be losing my HF inside the machine. I have the side panel off and turned down my lights. While standing on the pedal I see no flashes or glow inside the machine other than the HF contacts.

    The torch is a brand new cheapy air cooled #17. The ground is a brand new clamp on a cable I stole off my functional MIG for the moment.

    What else should I be checking?

  • #2
    Capacitor C2 is open, HF knob R5 is open, or coupling transformer T3 has some junk in it, or lead 58 or 59 had a poor connection. Any of these will still allow HF to be made... It's just not getting to the work lead. C2 needs to be a good, heavy duty capacitor rated for 10,000V.

    80% of failures are from 20% of causes
    Never compromise your principles today in the name of furthering them in the future.
    "All I ever wanted was an honest week's pay for an honest day's work." -Sgt. Bilko
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    • #3
      Often on my machine if I touch the tungsten to the work piece just before I weld, then lift it slightly before hitting the pedal, it works.

      Don't know why it works, but several guys have told me they do the same.

      Here is a tech manual I have saved in a drop box:
      https://www.dropbox.com/sh/7ijbgx67wuq6ivd/sYvAlvq_LC
      "Beware of false knowledge; it is more dangerous than ignorance." ~George Bernard Shaw~

      Airco 300 Heliwelder
      Dialarc 250 AC/DC
      ESAB 161
      Invertec v250 and v300 Pro
      SA200
      Spectrum 700 plasma
      MM210
      Miller HF-15-1
      Dirty ugly tools - perfect

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      • #4
        Originally posted by MinnesotaDave View Post
        Often on my machine if I touch the tungsten to the work piece just before I weld, then lift it slightly before hitting the pedal, it works.

        Don't know why it works, but several guys have told me they do the same.

        Here is a tech manual I have saved in a drop box:
        https://www.dropbox.com/sh/7ijbgx67wuq6ivd/sYvAlvq_LC

        The dialarc 250 HF behaved that way. I don't know why. Is it possible grounding the tungsten killed static charge that ionized water or air. HF at high voltage would be prone to wander where it isn't wanted. Ionizing encourages wandering.
        Dynasty 280DX
        Bobcat 250
        MM252
        Spool gun
        Twentieth Century 295
        Twentieth Century 295 AC
        Marquette spot welder
        Smith torches

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        • #5
          AC welding on a machine like this requires Continuous HF arc starting. As the arc goes from DC+ to DC- it is technically restarting the arc every time. So no good HF, No AC. If I can't weld AC the machine is far to large and lacking features for me to use it for my primary work(sheetmetal welding).

          I will check it over for those loose connections tomorrow.

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          • #6
            Originally posted by Bodybagger View Post
            Capacitor C2 is open, HF knob R5 is open, or coupling transformer T3 has some junk in it, or lead 58 or 59 had a poor connection. Any of these will still allow HF to be made... It's just not getting to the work lead. C2 needs to be a good, heavy duty capacitor rated for 10,000V.

            Ok I checked this stuff out and think I found some problems. I need confirmation.

            The Rotary Intensity Switch (R5) is all over the place on resistance. Some times Mega Ohms, sometimes Kila Ohms. If I go to 100% its in the Mega Ohms, if I go to about 90% its at just around 0 ohms. So I think the potentiometer is just screwed. Judging by the 90% being 0 ohms, I should be able to just wire the eyelets together and skip the switch until I can locate a new(er) one, right?

            Also the C2 capacitors seem to be a problem as well. I checked them and have an open. I should have some type of resistance reading/continuity shouldn't I? They don't appear to be original but that doesn't mean they aren't bad. They are only 6,000v rated ones as well. What resistance value should I be looking for? Going to go see if my local welding shop has them(HA).

            And what do you mean by "coupling transformer T3 has some junk in it", do you mean physically or electrically it isn't right? I am not sure how to test that component so I haven't yet. The connections on it are tight and don't appear to be corroded so I haven't messed with it yet.

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            • #7
              I reassembled the machine after I realized I was being stupid about the capacitors. I tested them again on my Farads setting on my dvom and they measured 2.89 nf which seemed close enough.

              The HF is now reaching the torch(with the intensity knob set, JUST right). Though a few times I had to scratch a little to wake it up, it started working then.

              The HF seems awful weak, but the last few machines I've used were brand spanking new Inverter machines so I am probably comparing Apples and Oranges.

              Thanks for the help folks.

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              • #8
                330A/BP, another no HF post

                Seems like if you think the HF isn't right then it probably isn't right. You sound like you have a lot of experience and a good knowledge base. The HF from the big old transformer machine I use and my nearly new inverter machines seem to be pretty close. Maybe I should do a side by side on my machines and see, then I might be able to toss out some useable comparative information if it'll help you out.

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                • #9
                  I finally got the Syncrowave 250 at my work fired up. After running that today I can definitely say the HF on my machine use dak. That Syncrowave had the strongest HF I've seen. Mine is definitely the weakest. So I now need to figure out why.

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                  • #10
                    Connect 58 and 59 on R5 together for maximum HF output. Darken the room and visually look at the coupling transformer for any arcing inside or around.

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